draft-ietf-rsvp-diagnostic-msgs-06.txt   draft-ietf-rsvp-diagnostic-msgs-07.txt 
INTERNET-DRAFT Andreas Terzis INTERNET-DRAFT Andreas Terzis
Expires: August 1999 UCLA Expires: October 1999 UCLA
<draft-ietf-rsvp-diagnostic-msgs-06.txt> Bob Braden <draft-ietf-rsvp-diagnostic-msgs-07.txt> Bob Braden
ISI ISI
Subramaniam Vincent Subramaniam Vincent
Cisco Systems Cisco Systems
Lixia Zhang Lixia Zhang
UCLA UCLA
February 1999 April 1999
RSVP Diagnostic Messages RSVP Diagnostic Messages
<draft-ietf-rsvp-diagnostic-msgs-06.txt> <draft-ietf-rsvp-diagnostic-msgs-07.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with all This document is an Internet-Draft and is in full conformance with
provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
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Force (IETF), its areas, and its working groups. Note that other groups Task Force (IETF), its areas, and its working groups. Note that
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Abstract Abstract
This document specifies the RSVP diagnostic facility, which allows a This document specifies the RSVP diagnostic facility, which allows a
user to collect information about the RSVP state along the path. This user to collect information about the RSVP state along a path. This
specification describes the functionality, diagnostic message formats, specification describes the functionality, diagnostic message
and processing rules. formats, and processing rules.
Changes Changes
A summary of the changes from the previous version (05) of this document A summary of the changes from the previous version (06) of this
follows: document follows:
- Added text in the Overview Section, to explain the role of the -Some editorial changes were made, using input from Tim Gleeson.
LAST-HOP node. Section 4.1 was also updated with rules for DREQ The technical content of the document has not changed from the
processing at RSVP nodes downstream of the LAST-HOP. previous version.
- The Next-Hop RSVP_HOP object was moved out of the DIAGNOSTIC
object. It's new place is directly after the Session object and
before the DIAGNOSTIC object. This was done to simplify implementa-
tion and to comply with object order in other RSVP messages. The IP
address of this RSVP_HOP object now carries the address of the
interface from which the DREQ is sent. While the IP address is not
(currently) used, this was done to conform with the use of RSVP_HOP
objects in other RSVP messages.
- A minimum value for the Path MTU field is defined.
- In the description of the DIAG_SELECT object, new text is added
explaining where the information requested by object types can be
collected from.
- The text explaining the use of the Previous RSVP-Hop Router Address
in the DIAG_RESPONSE object was changed. The previous version
incorrectly said that this address was the address of the interface
through which the DREQ would be forwarded. It is actually the
address *to* which the DREQ message will be forwarded.
- In the DIAGNOSTIC object, the LAST-HOP IP address was moved in
front of the SENDER_TEMPLATE.
- The H bit was removed. The existence of the ROUTE object signifies
whether the DREQ should be returned hop-by-hop.
- The "MTU too big" error was renamed to "packet too big" to reflect
more closely the situation under which it is generated.
- Section 4.1 (DREQ Packet Forwarding) was revamped
- The Send_DREP() section was rewritten
- Section 4.2 (DREP Forwarding) was updated.
- Section 4.3 (MTU Selection and Adjustment) was updated.
1. Introduction 1. Introduction
In the basic RSVP protocol [RSVP], error messages are the only means for In the basic RSVP protocol [RSVP], error messages are the only means
an end host to receive feedback regarding a failure in setting up either for an end host to receive feedback regarding a failure in setting up
path state or reservation state. An error message carries back only the either path state or reservation state. An error message carries
information from the failed point, without any information about the back only the information from the failed point, without any
state at other hops before or after the failure. In the absence of information about the state at other hops before or after the
failures, a host receives no feedback regarding the details of a reser- failure. In the absence of failures, a host receives no feedback
vation that has been put in place, such as whether, or where, or how, regarding the details of a reservation that has been put in place,
its own reservation request is being merged with that of others. Such such as whether, or where, or how, its own reservation request is
missing information can be highly desirable for debugging purpose, or being merged with that of others. Such missing information can be
highly desirable for debugging purposes, or for network resource
for network resource management in general. management in general.
This document specifies the RSVP diagnostic facility, which is designed This document specifies the RSVP diagnostic facility, which is
to fill this information gap. The diagnostic facility can be used to designed to fill this information gap. The diagnostic facility can
collect and report RSVP state information along the path from a receiver be used to collect and report RSVP state information along the path
to a specific sender. It uses Diagnostic messages that are independent from a receiver to a specific sender. It uses Diagnostic messages
of other RSVP control messages and produce no side-effects; that is, that are independent of other RSVP control messages and produce no
they do not change any RSVP state at either nodes or hosts. Similarly, side-effects; that is, they do not change any RSVP state at either
they provide not an error report but rather a collection of requested nodes or hosts. Similarly, they provide not an error report but
RSVP state information. rather a collection of requested RSVP state information.
The RSVP diagnostic facility was designed with the following goals: The RSVP diagnostic facility was designed with the following goals:
- To collect RSVP state information from every RSVP-capable hop along - To collect RSVP state information from every RSVP-capable hop
a path defined by path state, either for an existing reservation or along a path defined by path state, either for an existing
before a reservation request is made. More specifically, we want reservation or before a reservation request is made. More
to be able to collect information about flowspecs, refresh timer specifically, we want to be able to collect information about
values, and reservation merging at each hop along the path. flowspecs, refresh timer values, and reservation merging at each
hop along the path.
- To collect the IP hop count across each non-RSVP cloud. - To collect the IP hop count across each non-RSVP cloud.
- To avoid diagnostic packet implosion or explosion. - To avoid diagnostic packet implosion or explosion.
The following is specifically identified as a non-goal: The following is specifically identified as a non-goal:
- Checking the resource availability along a path. Such functional- - Checking the resource availability along a path. Such
ity may be useful for future reservation requests, but it would functionality may be useful for future reservation requests, but
require modifications to existing admission control modules that is it would require modifications to existing admission control
beyond the scope of RSVP. modules that is beyond the scope of RSVP.
2. Overview 2. Overview
The diagnostic facility introduces two new RSVP message types: Diagnos- The diagnostic facility introduces two new RSVP message types:
tic Request (DREQ) and Diagnostic Reply (DREP). A DREQ message can be Diagnostic Request (DREQ) and Diagnostic Reply (DREP). A DREQ
originated by a client in a "requester" host, which may or may not be a message can be originated by a client in a "requester" host, which
participant of the RSVP session to be diagnosed. A client in the may or may not be a participant of the RSVP session to be diagnosed.
requester host invokes the RSVP diagnostic facility by generating a DREQ A client in the requester host invokes the RSVP diagnostic facility
packet and sending it towards the LAST-HOP node, which should be on the by generating a DREQ packet and sending it towards the LAST-HOP node,
RSVP path to be diagnosed. This DREQ packet specifies the RSVP session which should be on the RSVP path to be diagnosed. This DREQ packet
and a sender host for that session. Starting from the LAST-HOP, the DREQ specifies the RSVP session and a sender host for that session.
packet collects information hop-by-hop as it is forwarded towards the Starting from the LAST-HOP, the DREQ packet collects information
sender (see Figure 1), until it reaches the ending node. Specifically, hop-by-hop as it is forwarded towards the sender (see Figure 1),
each RSVP-capable hop adds to the DREQ message a response until it reaches the ending node. Specifically, each RSVP-capable
(DIAG_RESPONSE) object containing local RSVP state for the specified hop adds to the DREQ message a response (DIAG_RESPONSE) object
RSVP session. containing local RSVP state for the specified RSVP session.
When the DREQ packet reaches the ending node, the message type is When the DREQ packet reaches the ending node, the message type is
changed to Diagnostic Reply (DREP) and the completed response is sent
to the original requester node. Partial responses may also be
returned before the DREQ packet reaches the ending node if an error
condition along the path, such as "no path state", prevents further
forwarding of the DREQ packet. To avoid packet implosion or
explosion, all diagnostic packets are forwarded via unicast only.
changed to Diagnostic Reply (DREP) and the completed response is sent to Thus, there are generally three nodes (hosts and/or routers) involved
the original requester node. Partial responses may also be returned in performing the diagnostic function: the requester node, the
before the DREQ packet reaches the ending node if an error condition starting node, and the ending node, as shown in Figure 1. It is
along the path, such as "no path state", prevents further forwarding of possible that the client invoking the diagnosis function may reside
the DREQ packet. To avoid packet implosion or explosion, all diagnostic directly on the starting node, in which case that the first two nodes
packets are forwarded via unicast only. are the same. The starting node is named "LAST-HOP", meaning the
last-hop of the path segment to be diagnosed. The LAST-HOP node can
Thus, there are generally three nodes (hosts and/or routers) involved in be either a receiver node or an intermediate node along the path.
performing the diagnostic function: the requester node, the starting The ending node is usually the specified sender host. However, the
node, and the ending node, as shown in Figure 1. It is possible that client can limit the length of the path segment to be diagnosed by
the client invoking the diagnosis function may reside directly on the specifying a hop-count limit in the DREQ message.
starting node, in which case that the first two nodes are the same. The
starting node is named "LAST-HOP", meaning the last-hop of the path seg-
ment to be diagnosed. The LAST-HOP node can be either a receiver node
or an intermediate node along the path. The ending node is usually the
specified sender host. However, the client can limit the length of the
path segment to be diagnosed by specifying a hop-count limit in the DREQ
message.
LAST-HOP Ending LAST-HOP Ending
Receiver node node Sender Receiver node node Sender
__ __ __ __ __ __ __ __ __ __
| |---------| |------>| |--> ...-->| |--> ...---->| | | |---------| |------>| |--> ...-->| |--> ...---->| |
|__| |__| DREQ |__| DREQ |__| DREQ |__| |__| |__| DREQ |__| DREQ |__| DREQ |__|
^ . | ^ . |
| . | | . |
| DREQ . DREP | DREP | DREQ . DREP | DREP
| . | | . |
_|_ DREP V V _|_ DREP V V
Requester | | <------------------------------------ Requester | | <------------------------------------
(client) |___| (client) |___|
Figure 1 Figure 1
DREP packets can be unicast from the ending node back to the requester DREP packets can be unicast from the ending node back to the
either directly or hop-by-hop along the reverse of the path taken by the requester either directly or hop-by-hop along the reverse of the path
DREQ message to the LAST-HOP, and thence to the requester. The direct taken by the DREQ message to the LAST-HOP, and thence to the
return is faster and more efficient, but the hop-by-hop reverse-path requester. The direct return is faster and more efficient, but the
route may be the only choice if the packets have to cross firewalls. hop-by-hop reverse-path route may be the only choice if the packets
Hop-by-hop return is accomplished using an optional ROUTE object, which have to cross firewalls. Hop-by-hop return is accomplished using an
is built incrementally to contain a list of node addresses that the DREQ optional ROUTE object, which is built incrementally to contain a list
packet has passed through. The ROUTE object is then used in reverse as of node addresses that the DREQ packet has passed through. The ROUTE
a source route to forward the DREP hop-by-hop back to the LAST-HOP node. object is then used in reverse as a source route to forward the DREP
hop-by-hop back to the LAST-HOP node.
A DREQ message always consists of a single unfragmented IP datagram. On A DREQ message always consists of a single unfragmented IP datagram.
the other hand, one DREQ message can generate multiple DREP packets, On the other hand, one DREQ message can generate multiple DREP
each containing a fragment of the total DREQ message. When the path packets, each containing a fragment of the total DREQ message. When
consists of many hops, the total length of a DREP message will exceed the path consists of many hops, the total length of a DREP message
the MTU size before reaching the sender; thus, the message has to be will exceed the MTU size before reaching the ending node; thus, the
fragmented. Relying on IP fragmentation and reassembly, however, can be message has to be fragmented. Relying on IP fragmentation and
problematic, especially when DREP messages are returned to the requester reassembly, however, can be problematic, especially when DREP
hop-by-hop, in which case fragmentation/reassembly would have to be per- messages are returned to the requester hop-by-hop, in which case
formed at every hop. To avoid such excessive overhead, we let the fragmentation/reassembly would have to be performed at every hop. To
requester define a default path MTU size that is carried in every DREQ avoid such excessive overhead, we let the requester define a default
packet. If an intermediate node finds that the default MTU size is big- path MTU size that is carried in every DREQ packet. If an
ger than the MTU of the incoming interface, it reduces the default MTU intermediate node finds that the default MTU size is bigger than the
size to the MTU size of the incoming interface. If an intermediate node MTU of the incoming interface, it reduces the default MTU size to the
detects that a DREQ packet size is larger than the default MTU size, it MTU size of the incoming interface. If an intermediate node detects
returns to the requester (in either manner described above) a DREP frag- that a DREQ packet size is larger than the default MTU size, it
ment containing accumulated responses. It then removes these responses returns to the requester (in either manner described above) a DREP
from the DREQ and continues to forward it. The requester node can fragment containing accumulated responses. It then removes these
reassemble the resulting DREP fragments into a complete DREP message. responses from the DREQ and continues to forward it. The requester
node can reassemble the resulting DREP fragments into a complete DREP
message.
When discussing diagnostic packet handling, this document uses direction When discussing diagnostic packet handling, this document uses
terminology that is consistent with the RSVP functional specification direction terminology that is consistent with the RSVP functional
[RSVP], relative to the direction of data packet flow. Thus, a DREQ specification [RSVP], relative to the direction of data packet flow.
packet enters a node through an "outgoing interface" and is forwarded Thus, a DREQ packet enters a node through an "outgoing interface" and
towards the sender through an "incoming interface", because DREQ packets is forwarded towards the sender through an "incoming interface",
travel in the reverse direction to the data flow. because DREQ packets travel in the reverse direction to the data
flow.
Notice that DREQ packets can be forwarded only after the RSVP path state Notice that DREQ packets can be forwarded only after the RSVP path
has been set up. If no path state exists, one may resort to the tracer- state has been set up. If no path state exists, one may resort to
oute or mtrace facility to examine whether the unicast/multicast routing the traceroute or mtrace facility to examine whether the
is working correctly. unicast/multicast routing is working correctly.
3. Diagnostic Packet Format 3. Diagnostic Packet Format
Like other RSVP messages, DREQ and DREP messages consist of an RSVP Com- Like other RSVP messages, DREQ and DREP messages consist of an RSVP
mon Header followed by a variable set of typed RSVP data objects. The Common Header followed by a variable set of typed RSVP data objects.
following sequence must be used: The following sequence must be used:
+-----------------------------------+ +-----------------------------------+
| RSVP Common Header | | RSVP Common Header |
+-----------------------------------+ +-----------------------------------+
| Session object | | Session object |
+-----------------------------------+ +-----------------------------------+
| Next-Hop RSVP_HOP object | | Next-Hop RSVP_HOP object |
+-----------------------------------+ +-----------------------------------+
| DIAGNOSTIC object | | DIAGNOSTIC object |
+-----------------------------------+ +-----------------------------------+
skipping to change at page 6, line 26 skipping to change at page 6, line 7
| (optional) ROUTE object | | (optional) ROUTE object |
+-----------------------------------+ +-----------------------------------+
| zero or more DIAG_RESPONSE objects| | zero or more DIAG_RESPONSE objects|
+-----------------------------------+ +-----------------------------------+
The session object identifies the RSVP session for which the state The session object identifies the RSVP session for which the state
information is being collected. We describe each of the other parts. information is being collected. We describe each of the other parts.
3.1. RSVP Message Common Header 3.1. RSVP Message Common Header
The RSVP message common header is defined in [RSVP]. The following spe- The RSVP message common header is defined in [RSVP]. The following
cific exceptions and extensions are needed for DREP and DREQ. specific exceptions and extensions are needed for DREP and DREQ.
Type field: define: Type field: define:
Type = 8: DREQ Diagnostic Request Type = 8: DREQ Diagnostic Request
Type = 9: DREP Diagnostic Reply Type = 9: DREP Diagnostic Reply
RSVP length: RSVP length:
If this is a DREP message and the MF flag in the DIAGNOSTIC object If this is a DREP message and the MF flag in the DIAGNOSTIC object
(see below) is set, this field indicates the length of this single (see below) is set, this field indicates the length of this single
DREP fragment rather than the total length of the complete DREP reply DREP fragment rather than the total length of the complete DREP
message (which cannot generally be known in advance). reply message (which cannot generally be known in advance).
3.2. Next-Hop RSVP_HOP Object 3.2. Next-Hop RSVP_HOP Object
This RSVP_HOP object carries the LIH of the interface through which the This RSVP_HOP object carries the LIH of the interface through which
DREQ should be received at the upstream node. This object is updated the DREQ should be received at the upstream node. This object is
hop-by hop. It is used for the same reasons that a RESV message contains updated hop-by hop. It is used for the same reasons that a RESV
an RSVP_HOP object: to distinguish logical interfaces and avoid problems message contains an RSVP_HOP object: to distinguish logical
interfaces and avoid problems caused by routing asymmetries and non-
caused by routing asymmetries and non-RSVP clouds. RSVP clouds.
While the IP address is not really used during DREQ processing we While the IP address is not really used during DREQ processing , for
decided, for consistency with the use of RSVP_HOP object in other RSVP consistency with the use of the RSVP_HOP object in other RSVP
messages, the IP address in the RSVP_HOP object to contain the address messages, the IP address in the RSVP_HOP object to contain the
of the interface through which a DREQ was sent. address of the interface through which the DREQ was sent.
3.3. DIAGNOSTIC Object 3.3. DIAGNOSTIC Object
A DIAGNOSTIC object contains the common diagnostic control information A DIAGNOSTIC object contains the common diagnostic control
in both DREQ and DREP messages. information in both DREQ and DREP messages.
o IPv4 DIAGNOSTIC object: Class = 30, C-Type = 1 o IPv4 DIAGNOSTIC object: Class = 30, C-Type = 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max-RSVP-hops | RSVP-hop-count| Reserved |MF| | Max-RSVP-hops | RSVP-hop-count| Reserved |MF|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Request ID | | Request ID |
+---------------+---------------+---------------+---------------+ +---------------+---------------+---------------+---------------+
| Path MTU | Fragment Offset | | Path MTU | Fragment Offset |
+---------------+---------------+---------------+---------------+ +---------------+---------------+---------------+---------------+
| LAST-HOP Address | | LAST-HOP Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
skipping to change at page 7, line 37 skipping to change at page 7, line 22
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| SENDER_TEMPLATE object | | SENDER_TEMPLATE object |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Requester FILTER_SPEC object | | Requester FILTER_SPEC object |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Here all IP addresses use the 4 byte IPv4 format, both explicitly in the Here all IP addresses use the 4 byte IPv4 format, both explicitly in
LAST-HOP Address and by using the IPv4 forms of the embedded FILTER_SPEC the LAST-HOP Address and by using the IPv4 forms of the embedded
and RSVP_HOP objects. FILTER_SPEC and RSVP_HOP objects.
o IPv6 DIAGNOSTIC object: Class = 30, C-Type = 2 o IPv6 DIAGNOSTIC object: Class = 30, C-Type = 2
The format is the same, except all explicit and embedded IP addresses The format is the same, except all explicit and embedded IP addresses
are 16 byte IPv6 addresses. are 16 byte IPv6 addresses.
The fields are as follows: The fields are as follows:
Max-RSVP-hops Max-RSVP-hops
An octet specifying the maximum number of RSVP hops over which infor-
mation will be collected. If an error condition in the middle of the An octet specifying the maximum number of RSVP hops over which
path prevents the DREQ packet from reaching the specified ending information will be collected. If an error condition in the
node, the Max-RSVP-hops field may be used to perform an expanding- middle of the path prevents the DREQ packet from reaching the
length search to reach the point just before the problem. If this specified ending node, the Max-RSVP-hops field may be used to
value is 1, the starting node and the ending node of the query will perform an expanding-length search to reach the point just before
be the same. If it is zero, there is no hop limit. the problem. If this value is 1, the starting node and the ending
node of the query will be the same. If it is zero, there is no
hop limit.
RSVP-hop-count RSVP-hop-count
Records the number of RSVP hops that have been traversed so far. If Records the number of RSVP hops that have been traversed so far.
the starting and ending nodes are the same, this value will be 1 in If the starting and ending nodes are the same, this value will be
the resulting DREP message. 1 in the resulting DREP message.
Fragment Offset Fragment Offset
Indicates where this DREP fragment belongs in the complete DREP mes- Indicates where this DREP fragment belongs in the complete DREP
sage, measured in octets. The first fragment has offset zero. Frag- message, measured in octets. The first fragment has offset zero.
ment Offset is used to determine if a DREQ message containing zero Fragment Offset is used to determine if a DREQ message containing
DIAG_RESPONSE objects should be processed at an RSVP capable node. zero DIAG_RESPONSE objects should be processed at an RSVP capable
node.
MF flag MF flag
Flag means "more fragments". It must be set to zero (0) in all DREQ Flag means "more fragments". It must be set to zero (0) in all
messages. It must be set to one (1) in all DREP packets that carry DREQ messages. It must be set to one (1) in all DREP packets that
partial results and are returned by intermediate nodes due to the MTU carry partial results and are returned by intermediate nodes due
limit. When the DREQ message is converted to a DREP message in the to the MTU limit. When the DREQ message is converted to a DREP
ending node, the MF flag must remain zero. message in the ending node, the MF flag must remain zero.
Request ID Request ID
Identifies an individual DREQ message and the corresponding DREP mes- Identifies an individual DREQ message and the corresponding DREP
sage (or all the fragments of the reply message). message (or all the fragments of the reply message).
One possible way to defining the Request ID would use 16 bits to One possible way to define the Request ID would use 16 bits to
specify the ID of the process making the query and 16 bits to distin- specify the ID of the process making the query and 16 bits to
guish different queries from this process. distinguish different queries from this process.
Path MTU Path MTU
Specifies a default MTU size in octets for DREP and DREQ messages. Specifies a default MTU size in octets for DREP and DREQ messages.
This value should not be smaller than the size of the "base" DREQ This value should not be smaller than the size of the "base" DREQ
packet. A "base" DREQ packet is one that contains a Common Header, a packet. A "base" DREQ packet is one that contains a Common Header,
Session object , a Next-Hop RSVP_HOP object, a DIAGNOSTIC object, an a Session object , a Next-Hop RSVP_HOP object, a DIAGNOSTIC
empty ROUTE object and a single default DIAG_RESPONSE (see below). object, an empty ROUTE object and a single default DIAG_RESPONSE
The assumption made here is that a diagnostic packet of this size can (see below). The assumption made here is that a diagnostic packet
always be forwarded without being fragmented. of this size can always be forwarded without being fragmented.
LAST-HOP Address LAST-HOP Address
The IP address of the LAST-HOP node. The DREQ message starts col- The IP address of the LAST-HOP node. The DREQ message starts
lecting information at this node and proceeds toward the sender. collecting information at this node and proceeds toward the
sender.
SENDER_TEMPLATE object SENDER_TEMPLATE object
This IPv4/IPv6 SENDER_TEMPLATE object contains the IP address and the This IPv4/IPv6 SENDER_TEMPLATE object contains the IP address and
port of a sender for the session being diagnosed. The DREQ packet is the port of a sender for the session being diagnosed. The DREQ
forwarded hop-by-hop towards this address. packet is forwarded hop-by-hop towards this address.
Requester FILTER_SPEC Object Requester FILTER_SPEC Object
This IPv4/IPv6 FILTER_SPEC object contains the IP address and the This IPv4/IPv6 FILTER_SPEC object contains the IP address and the
port from which the request originated and to which the DREP mes- port from which the request originated and to which the DREP
sage(s) should be sent. message(s) should be sent.
3.4. DIAG_SELECT Object 3.4. DIAG_SELECT Object
o DIAG_SELECT Class = 33, C-Type = 0. o DIAG_SELECT Class = 33, C-Type = 0.
A Diagnostic message may optionally contain a DIAG_SELECT object to A Diagnostic message may optionally contain a DIAG_SELECT object to
specify which specific RSVP objects should be reported in a specify which specific RSVP objects should be reported in a
DIAG_RESPONSE object. In the absence of a DIAG_SELECT object, the DIAG_RESPONSE object. In the absence of a DIAG_SELECT object, the
DIAG_RESPONSE object added by the node will contain a default set of DIAG_RESPONSE object added by the node will contain a default set of
object types (see DIAG_RESPONSE object below). object types (see DIAG_RESPONSE object below).
The DIAG_SELECT object contains a list of [Class, C-type] pairs, in the The DIAG_SELECT object contains a list of [Class, C-type] pairs, in
following format: the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| class | C-Type | class | C-Type | | class | C-Type | class | C-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// // // //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| class | C-Type | class | C-Type | | class | C-Type | class | C-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When a DIAG_SELECT object is included in a DREQ message, each RSVP node When a DIAG_SELECT object is included in a DREQ message, each RSVP
along the path will add a DIAG_RESPONSE object containing response node along the path will add a DIAG_RESPONSE object containing
objects (see below) whose classes and C-Types match entries in the response objects (see below) whose classes and C-Types match entries
DIAG_SELECT list (and are from matching path and reservation state). A in the DIAG_SELECT list (and are from matching path and reservation
C-type octet of zero is a 'wildcard', matching any C-Type associated state). A C-type octet of zero is a 'wildcard', matching any C-Type
with the associated class. associated with the associated class.
Depending on the type of objects requested, a node can find the associ- Depending on the type of objects requested, a node can find the
ated information in the path or reservation state stored for the session associated information in the path or reservation state stored for
described in the SESSION object. Specifically, information for the the session described in the SESSION object. Specifically,
RSVP_HOP,SENDER_TEMPLATE, SENDER_TSPEC, ADSPEC and FILTER_SPEC objects information for the RSVP_HOP,SENDER_TEMPLATE, SENDER_TSPEC, ADSPEC
can be extracted from the node's path state, while information for the and FILTER_SPEC objects can be extracted from the node's path state,
FLOWSPEC, CONFIRM, STYLE and SCOPE objects can be found in the node's while information for the FLOWSPEC, CONFIRM, STYLE and SCOPE objects
reservation state (if existent). can be found in the node's reservation state (if existent).
If the number of [Class, C-Type] pairs is odd, the last two octets of If the number of [Class, C-Type] pairs is odd, the last two octets of
the DIAG_SELECT object must be zero. A maximum DIAG_SELECT object is the DIAG_SELECT object must be zero. A maximum DIAG_SELECT object is
one that contains the [Class, C-type] pairs for all the RSVP objects one that contains the [Class, C-type] pairs for all the RSVP objects
that can be requested in a Diagnostic query. that can be requested in a Diagnostic query.
3.5. ROUTE Object 3.5. ROUTE Object
A diagnostic message may contain a ROUTE object, which is used to record A diagnostic message may contain a ROUTE object, which is used to
the route of the DREQ message and as a source route for returning the record the route of the DREQ message and as a source route for
DREP message(s) hop-by-hop. returning the DREP message(s) hop-by-hop.
o IPv4 ROUTE object: Class = 31, C-Type = 1. o IPv4 ROUTE object: Class = 31, C-Type = 1.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| reserved | R-pointer | | reserved | R-pointer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ RSVP Node List | + RSVP Node List |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This message signifies how the reply should be returned. If it does not This message signifies how the reply should be returned. If it does
exist in the DREQ packet then DREP packets should be sent to the not exist in the DREQ packet then DREP packets should be sent to the
response address directly. If it does exist, DREP packets must be requester directly. If it does exist, DREP packets must be returned
returned hop-by-hop along the reverse path to the LAST-HOP node and hop-by-hop along the reverse path to the LAST-HOP node and thence to
thence to the requester node. the requester node.
An empty ROUTE object is one that has an empty RSVP Node list and R- An empty ROUTE object is one that has an empty RSVP Node list and R-
pointer is equal to zero. pointer is equal to zero.
RSVP Node List RSVP Node List
A list of RSVP node IPv4 addresses. The number of addresses in this A list of RSVP node IPv4 addresses. The number of addresses in
list can be computed from the object size. this list can be computed from the object size.
R-pointer R-pointer
Used in DREP messages only (see Section 4.2 for details), but it is
incremented as each hop adds its incoming interface address in the Used in DREP messages only (see Section 4.2 for details), but it
ROUTE object. is incremented as each hop adds its incoming interface address in
the ROUTE object.
o IPv6 ROUTE object: Class = 31, C-Type = 2 o IPv6 ROUTE object: Class = 31, C-Type = 2
The same, except RSVP Node List contains IPv6 addresses. The same, except RSVP Node List contains IPv6 addresses.
In a DREQ message, RSVP Node List specifies all RSVP hops between the In a DREQ message, RSVP Node List specifies all RSVP hops between the
LAST-HOP address specified in the DIAGNOSTIC object, and the last RSVP LAST-HOP address specified in the DIAGNOSTIC object, and the last
node the DREQ message has visited. In a DREP message, RSVP Node List RSVP node the DREQ message has visited. In a DREP message, RSVP Node
specifies all RSVP hops between the LAST-HOP and the node that returns List specifies all RSVP hops between the LAST-HOP and the node that
this DREP message. returns this DREP message.
3.6. DIAG_RESPONSE Object 3.6. DIAG_RESPONSE Object
Each RSVP node attaches DIAG_RESPONSE object to each DREQ message it Each RSVP node attaches a DIAG_RESPONSE object to each DREQ message
receives, before forwarding the message. The DIAG_RESPONSE object con- it receives, before forwarding the message. The DIAG_RESPONSE object
tains the state to be reported for this node. It has a fixed-format contains the state to be reported for this node. It has a fixed-
header and then a variable list of RSVP state objects, or "response format header and then a variable list of RSVP state objects, or
objects". "response objects".
o IPv4 DIAG_RESPONSE object: Class = 32, C-Type = 1. o IPv4 DIAG_RESPONSE object: Class = 32, C-Type = 1.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DREQ Arrival Time | | DREQ Arrival Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Incoming Interface Address | | Incoming Interface Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outgoing Interface Address | | Outgoing Interface Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 12, line 7 skipping to change at page 11, line 41
| (optional) TUNNEL object | | (optional) TUNNEL object |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Response objects // // Response objects //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o IPv6 DIAG_RESPONSE object: Class = 32, C-Type = 2. o IPv6 DIAG_RESPONSE object: Class = 32, C-Type = 2.
This object has the same format, except that all explicit and embedded This object has the same format, except that all explicit and
IP addresses are IPv6 addresses. embedded IP addresses are IPv6 addresses.
The fields are as follows: The fields are as follows:
DREQ Arrival Time DREQ Arrival Time
A 32-bit NTP timestamp specifying the time the DREQ message
A 32-bit NTP timestamp specifying the time the DREQ message arrived arrived at this node. The 32-bit form of an NTP timestamp
at this node. The 32-bit form of an NTP timestamp consists of the consists of the middle 32 bits of the full 64-bit form, that is,
middle 32 bits of the full 64-bit form, that is, the low 16 bits of the low 16 bits of the integer part and the high 16 bits of the
the integer part and the high 16 bits of the fractional part. fractional part.
Incoming Interface Address Incoming Interface Address
Specifies the IP address of the interface on which messages from the Specifies the IP address of the interface on which messages from
sender are expected to arrive, or 0 if unknown. the sender are expected to arrive, or 0 if unknown.
Outgoing Interface Address Outgoing Interface Address
Specifies the IP address of the interface through which the DREQ mes- Specifies the IP address of the interface through which the DREQ
sage arrived and to which messages from the given sender and for the message arrived and to which messages from the given sender and
specified session address flow, or 0 if unknown. for the specified session address flow, or 0 if unknown.
Previous-RSVP-Hop Router Address Previous-RSVP-Hop Router Address
Specifies the IP address from which this node receives RSVP PATH mes- Specifies the IP address from which this node receives RSVP PATH
sages for this source, or 0 if unknown. This is also the interface messages for this source, or 0 if unknown. This is also the
to which the DREQ will be forwarded. interface to which the DREQ will be forwarded.
D-TTL D-TTL
The number of IP hops this DREQ message traveled from the down-stream The number of IP hops this DREQ message traveled from the down-
RSVP node to the current node. stream RSVP node to the current node.
M flag M flag
A single-bit flag which indicates whether the reservation described A single-bit flag which indicates whether the reservation
by the response objects, is merged with reservations from other down- described by the response objects is merged with reservations from
stream interfaces when being forwarded upstream. other downstream interfaces when being forwarded upstream.
R-error R-error
A 3-bit field that indicates error conditions at a node. Currently A 3-bit field that indicates error conditions at a node. Currently
defined values are: defined values are:
0x00: no error 0x00: no error
0x01: No PATH state 0x01: No PATH state
0x02: packet too big 0x02: packet too big
0x04: ROUTE object too big 0x04: ROUTE object too big
skipping to change at page 13, line 23 skipping to change at page 13, line 14
Timer value Timer value
The local refresh timer value in seconds. The local refresh timer value in seconds.
The set of response objects to be included at the end of the The set of response objects to be included at the end of the
DIAG_RESPONSE object is determined by a DIAG_SELECT object, if one is DIAG_RESPONSE object is determined by a DIAG_SELECT object, if one is
present. If no DIAG_SELECT object is present, the response objects present. If no DIAG_SELECT object is present, the response objects
belong to the default list of classes: belong to the default list of classes:
SENDER_TSPEC object FILTER_SPEC object FLOWSPEC object SENDER_TSPEC object FILTER_SPEC object
STYLE object FLOWSPEC object STYLE object
Any C-Type present in the local RSVP state will be used. These response Any C-Type present in the local RSVP state will be used. These
objects may be in any order but they must all be at the end of the response objects may be in any order but they must all be at the end
DIAG_RESPONSE object. of the DIAG_RESPONSE object.
A default DIAG_RESPONSE object is one containing the default list of A default DIAG_RESPONSE object is one containing the default list of
classes described above. classes described above.
3.7. TUNNEL Object 3.7. TUNNEL Object
The optional TUNNEL object should be inserted when a DREQ message The optional TUNNEL object should be inserted when a DREQ message
arrives at an RSVP node that acts as a tunnel exit point. arrives at an RSVP node that acts as a tunnel exit point.
The TUNNEL object provides mapping between the end-to-end RSVP session The TUNNEL object provides the mapping between the end-to-end RSVP
that is being diagnosed and the RSVP session over the tunnel. This map- session that is being diagnosed and the RSVP session over the tunnel.
ping information allows the diagnosis client to conduct diagnosis over This mapping information allows the diagnosis client to conduct
the involved tunnel session, by invoking a separate Diagnostic query for diagnosis over the involved tunnel session, by invoking a separate
the corresponding Tunnel Session and Tunnel Sender. Keep in mind, how- Diagnostic query for the corresponding Tunnel Session and Tunnel
ever, that multiple end-to-end sessions may all map to one pre-config- Sender. Keep in mind, however, that multiple end-to-end sessions may
ured tunnel session that may have totally different parameter settings. all map to one pre-configured tunnel session that may have totally
different parameter settings.
The tunnel object is defined in the RSVP Tunnel Specification [RSVPTUN]. The tunnel object is defined in the RSVP Tunnel Specification
[RSVPTUN].
4. Diagnostic Packet Forwarding Rules 4. Diagnostic Packet Forwarding Rules
4.1. DREQ Packet Forwarding 4.1. DREQ Packet Forwarding
DREQ messages are forwarded hop-by-hop via unicast from the LAST-HOP DREQ messages are forwarded hop-by-hop via unicast from the LAST-HOP
address to the Sender address, as specified in the DIAGNOSTIC object. address to the Sender address, as specified in the DIAGNOSTIC object.
If an RSVP capable node, other than the LAST-HOP node, receives a DREQ If an RSVP capable node, other than the LAST-HOP node, receives a
message that contains no DIAG_RESPONSE objects and has a zero Fragment DREQ message that contains no DIAG_RESPONSE objects and has a zero
Offset, the node should forward the DREQ packet towards the LAST-HOP Fragment Offset, the node should forward the DREQ packet towards the
without doing any of the processing mentioned below. The reason is that LAST-HOP without doing any of the processing mentioned below. The
such conditions apply only for nodes downstream of the LAST-HOP where no reason is that such conditions apply only for nodes downstream of the
information should be collected. LAST-HOP where no information should be collected.
Processing begins when a DREQ message, DREQ_in, arrives at a node. The Processing begins when a DREQ message, DREQ_in, arrives at a node.
following processing is performed before DREQ_in is forwarded: The following processing is performed before DREQ_in is forwarded:
1. Create a new DIAG_RESPONSE object. Compute the IP hop count from 1. Create a new DIAG_RESPONSE object. Compute the IP hop count from
the previous RSVP hop. This is done by subtracting the value of the the previous RSVP hop. This is done by subtracting the value of
TTL value in the IP header from Send_TTL in the RSVP common header. the TTL value in the IP header from Send_TTL in the RSVP common
Save the result in the D-TTL field of the DIAG_RESPONSE object. header. Save the result in the D-TTL field of the DIAG_RESPONSE
object.
2. Set the DREQ Arrival Time and the Outgoing Interface Address in the 2. Set the DREQ Arrival Time and the Outgoing Interface Address in
DIAG_RESPONSE object. If this node is the LAST-HOP, then the Out- the DIAG_RESPONSE object. If this node is the LAST-HOP, then
going Interface Address field in the DIAG_RESPONSE object contains the Outgoing Interface Address field in the DIAG_RESPONSE object
the following value depending on the session being diagnosed. contains the following value depending on the session being
diagnosed.
* If the session in question is a unicast session, then the Out- * If the session in question is a unicast session, then the
going Interface Address field contains the address of the Outgoing Interface Address field contains the address of
interface LAST-HOP uses to send PATH messages and data to the the interface LAST-HOP uses to send PATH messages and data
receiver specified by the session address. to the receiver specified by the session address.
* Otherwise, if it is a multicast session and there is at least * Otherwise, if it is a multicast session and there is at
one receiver for this session, LAST_HOP should use the address least one receiver for this session, LAST_HOP should use
of one of local interfaces used to reach one of the receivers. the address of one of local interfaces used to reach one of
the receivers.
* Otherwise Outgoing Interface Address should be zero. * Otherwise Outgoing Interface Address should be zero.
If no PATH state exists for the specified session, set R-error = If no PATH state exists for the specified session, set R-error =
0x01 (No PATH state). 0x01 (No PATH state).
3. Increment the RSVP-hop-count field in the DIAGNOSTIC message object 3. Increment the RSVP-hop-count field in the DIAGNOSTIC message
by one. object by one.
4. If the "No PATH state" bit is set, goto Send_DREP. 4. If the "No PATH state" bit is set, goto Send_DREP.
5. Set the rest of the fields in the DIAG_RESPONSE object. If DREQ_in 5. Set the rest of the fields in the DIAG_RESPONSE object. If
contains a DIAG_SELECT object, the response object classes are DREQ_in contains a DIAG_SELECT object, the response object
those specified in the DIAG_SELECT; otherwise, they are classes are those specified in the DIAG_SELECT; otherwise, they
SENDER_TSPEC, FILTER_SPEC, STYLE, and FLOWSPEC objects. If no are SENDER_TSPEC, FILTER_SPEC, STYLE, and FLOWSPEC objects. If
reservation state exists for the specified RSVP session, the no reservation state exists for the specified RSVP session, the
DIAG_RESPONSE object will contain no FILTER_SPEC or FLOWSPEC or DIAG_RESPONSE object will contain no FILTER_SPEC or FLOWSPEC or
STYLE object. If neither PATH nor reservation state exists for the STYLE object. If neither PATH nor reservation state exists for
specified RSVP session, then no response objects will be appended the specified RSVP session, then no response objects will be
to the DIAG_RESPONSE object. appended to the DIAG_RESPONSE object.
6. If RSVP-hop-count is equal to Max-RSVP-hops or this node is the 6. If RSVP-hop-count is equal to Max-RSVP-hops or this node is the
sender, go to Send_DREP. sender, go to Send_DREP.
7. If the Path MTU value is larger than the MTU size of the incoming 7. If the Path MTU value is larger than the MTU size of the
interface for the sender being diagnosed, change the Path MTU value incoming interface for the sender being diagnosed, change the
to the MTU value of the incoming interface. Path MTU value to the MTU value of the incoming interface.
8. If the size of DREQ_in plus the size of the new DIAG_RESPONSE 8. If the size of DREQ_in plus the size of the new DIAG_RESPONSE
object plus the size of an IP address ,if a ROUTE object exists, is object plus the size of an IP address ,if a ROUTE object exists,
larger than Path MTU set the "packet too big" (0x02) error bit in is larger than Path MTU set the "packet too big" (0x02) error
DIAG_RESPONSE, goto Send_DREP. bit in DIAG_RESPONSE, goto Send_DREP.
9. If a ROUTE object exists, append the "Incoming Interface Address" 9. If a ROUTE object exists, append the "Incoming Interface
to the end of the ROUTE object, increment R-Pointer by one, update Address" to the end of the ROUTE object, increment R-Pointer by
the Next-Hop RSVP_HOP object, append the new DIAG_RESPONSE object one, update the Next-Hop RSVP_HOP object, append the new
to the list of DIAG_RESPONSE object and update the message length DIAG_RESPONSE object to the list of DIAG_RESPONSE object and
field in the RSVP common header accordingly. Finally, forward update the message length field in the RSVP common header
DREQ_in to the next hop towards the sender, after recomputing the accordingly. Finally, forward DREQ_in to the next hop towards
checksum. Return. the sender, after recomputing the checksum. Return.
Send_DREP: Send_DREP:
1. If the size of DREQ_in plus the size of the new DIAG_RESPONSE 1. If the size of DREQ_in plus the size of the new DIAG_RESPONSE
object plus the size of an IP address ,if a ROUTE object exists, is object plus the size of an IP address ,if a ROUTE object exists,
larger than Path MTU set the "packet too big" (0x02) error bit in is larger than Path MTU set the "packet too big" (0x02) error
DIAG_RESPONSE, otherwise goto step 11. bit in DIAG_RESPONSE, otherwise goto step 11.
2. Make a copy of DREQ_in and change the type field in RSVP common 2. Make a copy of DREQ_in and change the type field in RSVP common
header from DREQ to DREP. Trim all DIAG_RESPONSE objects from header from DREQ to DREP. Trim all DIAG_RESPONSE objects from
DREQ_in and adjust the Fragment Offset. DREQ_in and adjust the Fragment Offset.
3. If a ROUTE object is present in the DREP message, decrement the R- 3. If a ROUTE object is present in the DREP message, decrement the
pointer and set target address to the last address in the ROUTE R-pointer and set target address to the last address in the
object, otherwise set target address to the requester address. Set ROUTE object, otherwise set target address to the requester
the MF bit, recompute the checksum and send the DREP message back address. Set the MF bit, recompute the checksum and send the
to the target address. DREP message back to the target address.
4. If the size of DREQ_in plus the size of DIAG_RESPONSE plus the size 4. If the size of DREQ_in plus the size of DIAG_RESPONSE plus the
of an IP address ,if a ROUTE object exists, is smaller than Path size of an IP address ,if a ROUTE object exists, is smaller than
MTU goto Step 9. Path MTU goto Step 9.
5. Make a copy of DREQ_in and change the type field in RSVP common 5. Make a copy of DREQ_in and change the type field in RSVP common
header from DREQ to DREP. If a ROUTE object exists, replace the header from DREQ to DREP. If a ROUTE object exists, replace the
ROUTE object in DREQ_in with an empty ROUTE object. Turn on the ROUTE object in DREQ_in with an empty ROUTE object. Turn on the
"ROUTE object too big" (0x04) error bit in the DIAG_RESPONSE. "ROUTE object too big" (0x04) error bit in the DIAG_RESPONSE.
6. If the "No PATH state" (0x01) error bit is set or if RSVP-hop-count 6. If the "No PATH state" (0x01) error bit is set or if RSVP-hop-
is equal to Max-RSVP-hops or if this node is the sender, goto Step count is equal to Max-RSVP-hops or if this node is the sender,
8. goto Step 8.
7. If a ROUTE object exists, append the "Incoming Interface Address" 7. If a ROUTE object exists, append the "Incoming Interface
to the end of the ROUTE object, increment R-Pointer by one, update Address" to the end of the ROUTE object, increment R-Pointer by
the Next-Hop RSVP_HOP object, append the new DIAG_RESPONSE object one, update the Next-Hop RSVP_HOP object, append the new
to the list of DIAG_RESPONSE object, update the message length DIAG_RESPONSE object to the list of DIAG_RESPONSE object, update
field in the RSVP common header accordingly and adjust the Fragment the message length field in the RSVP common header accordingly
Offset. Finally, forward DREQ_in to the next hop towards the and adjust the Fragment Offset. Finally, forward DREQ_in to the
sender, after recomputing the checksum. next hop towards the sender, after recomputing the checksum.
8. Append the DIAG_RESPONSE object to the end of DREP. Set target 8. Append the DIAG_RESPONSE object to the end of DREP. Set target
address to the requester address. Turn on the MF bit. Update the address to the requester address. Turn on the MF bit. Update the
packet length, recompute the checksum in the DREP message and send packet length, recompute the checksum in the DREP message and
it towards the target address. Return send it towards the target address. Return
9. If the "No PATH state" (0x01) error bit is set or if RSVP-hop-count 9. If the "No PATH state" (0x01) error bit is set or if RSVP-hop-
is equal to Max-RSVP-hops or if this node is the sender, goto Step count is equal to Max-RSVP-hops or if this node is the sender,
11. goto Step 11.
10. If a ROUTE object exists, append the "Incoming Interface Address" 10. If a ROUTE object exists, append the "Incoming Interface
to the end of the ROUTE object, increment R-Pointer by one, update Address" to the end of the ROUTE object, increment R-Pointer by
the Next-Hop RSVP_HOP object, append the new DIAG_RESPONSE object one, update the Next-Hop RSVP_HOP object, append the new
to the list of DIAG_RESPONSE object and update the message length DIAG_RESPONSE object to the list of DIAG_RESPONSE object and
field in the RSVP common header accordingly. Finally, forward update the message length field in the RSVP common header
DREQ_in to the next hop towards the sender, after recomputing the accordingly. Finally, forward DREQ_in to the next hop towards
checksum. Return. the sender, after recomputing the checksum. Return.
11. Append the DIAG_RESPONSE object to the end of DREQ_in. If a ROUTE 11. Append the DIAG_RESPONSE object to the end of DREQ_in. If a
object is present in the message, decrement the R-pointer and set ROUTE object is present in the message, decrement the R-pointer
target address to the last address in the ROUTE object, otherwise and set target address to the last address in the ROUTE object,
set target address to the requester address. Change the Type Field otherwise set target address to the requester address. Change
in the Common header from DREQ to DREP.Update the packet length, the Type Field in the Common header from DREQ to DREP.Update the
recompute the checksum in the DREP message and send it towards the packet length, recompute the checksum in the DREP message and
target address. The MF bit in this case must be off. send it towards the target address. The MF bit in this case must
be off.
4.2. DREP Forwarding 4.2. DREP Forwarding
When a ROUTE object is present, DREP messages are forwarded hop-by-hop When a ROUTE object is present, DREP messages are forwarded hop-by-
towards the requester, by reversing the route as listed in the ROUTE hop towards the requester, by reversing the route as listed in the
object. Otherwise, DREP messages are sent directly to the original ROUTE object. Otherwise, DREP messages are sent directly to the
requester. original requester.
When a node receives a DREP message, it simply decreases R-pointer by When a node receives a DREP message, it simply decreases R-pointer by
one (address length), recomputes the checksum and forwards the message one (address length), recomputes the checksum and forwards the
to the address pointed by R-pointer in the route list. If a node, other message to the address pointed to by R-pointer in the route list. If
than the LAST-HOP, receives a DREP packet where R-pointer is equal to a node, other than the LAST-HOP, receives a DREP packet where R-
zero, it must send it directly to the requester. pointer is equal to zero, it must send it directly to the requester.
When the LAST-HOP node receives a DREP message, it sends the message to When the LAST-HOP node receives a DREP message, it sends the message
the requester. to the requester.
4.3. MTU Selection and Adjustment 4.3. MTU Selection and Adjustment
Because the DREQ message carries the allowed MTU size of previous hops Because the DREQ message carries the allowed MTU size of previous
that the DREP messages will later traverse, this unique feature allows hops that the DREP messages will later traverse, this unique feature
the easy semantic fragmentation as described above. Whenever the DREQ allows easy semantic fragmentation as described above. Whenever the
message approaches the size of Path MTU, it can be trimmed before being DREQ message approaches the size of Path MTU, it can be trimmed
forwarded again. before being forwarded again.
When a requester sends a DREQ message, the Path MTU field in the DIAG-
NOSTIC object can be set to a configured default value. It is possible
that the original Path MTU value is chosen larger than the actual MTU
value along some portion of the path being traced. Therefore each
intermediate RSVP node must check the MTU value when processing a DREQ
message. If the specified MTU value is larger than the MTU of the
incoming interface (that the DREQ message will be forwarded to), the
node changes the MTU value in the header to the smaller value.
Whenever a DREQ message size becomes larger than the Path MTU value, an When a requester sends a DREQ message, the Path MTU field in the
intermediate RSVP node makes a copy of the message, converts it to a DIAGNOSTIC object can be set to a configured default value. It is
DREP message to send back, and then trims off the partial results from possible that the original Path MTU value is chosen larger than the
the DREQ message. If in this case also the DREQ cannot be forwarded actual MTU value along some portion of the path being traced.
upstream due to a large ROUTE object, the "ROUTE object too big" is set Therefore each intermediate RSVP node must check the MTU value when
and the ROUTE object is trimmed. As a result of the ROUTE object trim- processing a DREQ message. If the specified MTU value is larger than
ming, DREP(s) will come hop-by-hop up to this node and will then immedi- the MTU of the incoming interface (that the DREQ message will be
ately forwarded to the requester address. forwarded to), the node changes the MTU value in the header to the
smaller value.
Even if the steps shown above are followed there are a few cases where Whenever a DREQ message size becomes larger than the Path MTU value,
fragmentation at the IP layer will happen. For example, non-RSVP hops an intermediate RSVP node makes a copy of the message, converts it to
with smaller MTUs may exist before LAST-HOP is reached, or if the a DREP message to send back, and then trims off the partial results
response is sent directly back to requester (as opposed to hop by hop) from the DREQ message. If in this case also the DREQ cannot be
the DREP may take a different route to the requester than the DREQ took forwarded upstream due to a large ROUTE object, the "ROUTE object too
big" is set and the ROUTE object is trimmed. As a result of the ROUTE
object trimming, DREP(s) will come hop-by-hop up to this node and
will then immediately be forwarded to the requester address.
from the requester. Another case is when there exists a link with MTU Even if the steps shown above are followed there are a few cases
smaller than the minimum Path MTU value defined in Section 3.2. where fragmentation at the IP layer will happen. For example, non-
RSVP hops with smaller MTUs may exist before LAST-HOP is reached, or
if the response is sent directly back to requester (as opposed to hop
by hop) the DREP may take a different route to the requester than the
DREQ took from the requester. Another case is when there exists a
link with MTU smaller than the minimum Path MTU value defined in
Section 3.2.
4.4. Errors 4.4. Errors
If an error condition prevents a DREP message from being forwarded fur- If an error condition prevents a DREP message from being forwarded
ther, the message is simply dropped. further, the message is simply dropped.
If an error condition, such as lack of PATH state, prevents a DREQ mes- If an error condition, such as lack of PATH state, prevents a DREQ
sage from being forwarded further, the node must change the current mes- message from being forwarded further, the node must change the
sage to DREP type and return it to the response address. current message to DREP type and return it to the response address.
5. Problem Diagnosis by Using RSVP Diagnostic Facility 5. Problem Diagnosis by Using RSVP Diagnostic Facility
5.1. Across Firewalls 5.1. Across Firewalls
Firewalls may cause problems in diagnostic message forwarding. Let us Firewalls may cause problems in diagnostic message forwarding. Let
look at two different cases. us look at two different cases.
First, let us assume that the querier resides on a receiving host of the First, let us assume that the querier resides on a receiving host of
session to be examined. In this case, firewalls should not prevent the the session to be examined. In this case, firewalls should not
forwarding of the diagnostic messages in a hop-by-hop manner, assuming prevent the forwarding of the diagnostic messages in a hop-by-hop
that proper holes have been punched on the firewall to allow hop-by-hop manner, assuming that proper holes have been punched on the firewall
forwarding of other RSVP messages. The querier may start by not includ- to allow hop-by-hop forwarding of other RSVP messages. The querier
ing a ROUTE object, which can give a faster response delivery and may start by not including a ROUTE object, which can give a faster
reduced overhead at intermediate nodes. However if no response is response delivery and reduced overhead at intermediate nodes.
received, the querier may resend the DREQ message with a ROUTE object, However if no response is received, the querier may resend the DREQ
specifying that a hop-by-hop reply should be sent. message with a ROUTE object, specifying that a hop-by-hop reply
should be sent.
If the requester is a third party host and is separated from the LAST- If the requester is a third party host and is separated from the
HOP address by a firewall (either the requester is behind a firewall, or LAST-HOP address by a firewall (either the requester is behind a
the LAST-HOP is a node behind a firewall, or both), at this time we do firewall, or the LAST-HOP is a node behind a firewall, or both), at
not know any other solution but to change the LAST-HOP to a node that is this time we do not know any other solution but to change the LAST-
on the same side of the firewall as the requester. HOP to a node that is on the same side of the firewall as the
requester.
5.2. Examination of RSVP Timers 5.2. Examination of RSVP Timers
One can easily collect information about the current timer value at each One can easily collect information about the current timer value at
RSVP hop along the way. This will be very helpful in situations when each RSVP hop along the way. This will be very helpful in situations
the reservation state goes up and down frequently, to find out whether when the reservation state goes up and down frequently, to find out
the state changes are due to improper setting of timer values, or K val- whether the state changes are due to improper setting of timer
ues (when across lossy links), or frequent routing changes. values, or K values (when across lossy links), or frequent routing
changes.
5.3. Discovering Non-RSVP Clouds 5.3. Discovering Non-RSVP Clouds
The D-TTL field in each DIAG_RESPONSE object shows the number of routing The D-TTL field in each DIAG_RESPONSE object shows the number of
hops between adjacent RSVP nodes. Therefore any value greater than one routing hops between adjacent RSVP nodes. Therefore any value
indicates a non-RSVP clouds in between. Together with the arrival greater than one indicates a non-RSVP cloud in between. Together
timestamps (assuming NTP works), this value can also give some vague, with the arrival timestamps (assuming NTP works), this value can also
though not necessarily accurate, indication of how big that cloud might give some vague, though not necessarily accurate, indication of how
be. One might also find out all the intermediate non-RSVP nodes by run- big that cloud might be. One might also find out all the
ning either unicast or multicast trace route. intermediate non-RSVP nodes by running either unicast or multicast
trace route.
5.4. Discovering Reservation Merges 5.4. Discovering Reservation Merges
The flowspec value in a DIAG_RESPONSE object specifies the amount of The flowspec value in a DIAG_RESPONSE object specifies the amount of
resources being reserved for the data stream defined by the filter spec resources being reserved for the data stream defined by the filter
in the same data block. When this value of adjacent DIAG_RESPONSE spec in the same data block. When this value of adjacent
objects differs, that is, a downstream node Rd has a smaller value than DIAG_RESPONSE objects differs, that is, a downstream node Rd has a
its immediate upstream node Ru, it indicates a merge of reservation with smaller value than its immediate upstream node Ru, it indicates a
RSVP request(s) from other down stream interface(s) at Rd. Further, in merge of reservation with RSVP request(s) from other down stream
case of SE style reservation, one can examine how the different SE interface(s) at Rd. Further, in case of SE style reservation, one
scopes get merged at each hop. can examine how the different SE scopes get merged at each hop.
In particular, if a receiver sends a DREQ message before sending its own In particular, if a receiver sends a DREQ message before sending its
reservation, it can discover (1) how many RSVP hops there are along the own reservation, it can discover (1) how many RSVP hops there are
path between the specified sender and itself, (2) how many of the hops along the path between the specified sender and itself, (2) how many
already have some reservation by other receivers, and (3) possibly a of the hops already have some reservation by other receivers, and (3)
rough prediction of how its reservation request might get merged with possibly a rough prediction of how its reservation request might get
other existing ones. merged with other existing ones.
5.5. Error Diagnosis 5.5. Error Diagnosis
In addition to examining the state of a working reservation, RSVP diag- In addition to examining the state of a working reservation, RSVP
nostic messages are more likely to be invoked when things are not work- diagnostic messages are more likely to be invoked when things are not
ing correctly. For example, a receiver has reserved an adequate pipe working correctly. For example, a receiver has reserved an adequate
for a specified incoming data stream, yet the observed delay or loss pipe for a specified incoming data stream, yet the observed delay or
ratio is much higher than expected. In this case the receiver can use loss ratio is much higher than expected. In this case the receiver
the diagnostic facility to examine the reservation state at each RSVP can use the diagnostic facility to examine the reservation state at
hop along the way to find out whether the RSVP state is set up cor- each RSVP hop along the way to find out whether the RSVP state is set
rectly, whether there is any blackhole along the way that caused RSVP up correctly, whether there is any blackhole along the way that
message losses, or whether there are non-RSVP clouds, and where they caused RSVP message losses, or whether there are non-RSVP clouds, and
are, that may have caused the performance problem. where they are, that may have caused the performance problem.
5.6. Crossing "Legacy" RSVP Routers 5.6. Crossing "Legacy" RSVP Routers
Since this diagnosis facility was developed and added to RSVP after a Since this diagnosis facility was developed and added to RSVP after a
number of RSVP implementations were in place, it is possible, or even number of RSVP implementations were in place, it is possible, or even
likely, that when performing RSVP diagnosis, one may encounter one or likely, that when performing RSVP diagnosis, one may encounter one or
more RSVP-capable nodes that do not understand diagnostic messages and more RSVP-capable nodes that do not understand diagnostic messages
drop them. When this happens, the invoking client will get no response and drop them. When this happens, the invoking client will get no
from its requests. response from its requests.
One way to by-pass such "legacy" RSVP nodes is to perform RSVP diagnosis One way to by-pass such "legacy" RSVP nodes is to perform RSVP
repeatedly, guided by information from traceroute, or mtrace in case of diagnosis repeatedly, guided by information from traceroute, or
multicast. When an RSVP diagnostic query times out (see next section), mtrace in case of multicast. When an RSVP diagnostic query times out
one may first use traceroute to get the list of nodes along the path, (see next section), one may first use traceroute to get the list of
and then gradually increase the value of Max-RSVP-hops field in the DREQ nodes along the path, and then gradually increase the value of Max-
message, starting from a low value until one no longer receives a RSVP-hops field in the DREQ message, starting from a low value until
response. One can then try RSVP diagnosis again by starting with the one no longer receives a response. One can then try RSVP diagnosis
first node (which is further upstream towards the sender) after the again by starting with the first node (which is further upstream
unresponding one. towards the sender) after the unresponding one.
There are two problem with the method mentioned above in the case of There are two problem with the method mentioned above in the case of
unicast sessions. Both problems are related to the fact that traceroute unicast sessions. Both problems are related to the fact that
information provides the path from the requester to the sender. The traceroute information provides the path from the requester to the
first problem is that the LAST-HOP may not on the path from the sender. The first problem is that the LAST-HOP may not be on the path
requester to the sender. In this case we can get information only from from the requester to the sender. In this case we can get information
the portion of the path from the LAST-HOP to the sender which intersects only from the portion of the path from the LAST-HOP to the sender
with the path from the requester to the sender. If routers that are not which intersects with the path from the requester to the sender. If
on the intersection of the two paths don't have PATH state for the ses- routers that are not on the intersection of the two paths don't have
sion being diagnosed then they will reply with R-error=0x01. The PATH state for the session being diagnosed then they will reply with
requester can overcome this problem by sending a DREQ to every router on R-error=0x01. The requester can overcome this problem by sending a
the path (from itself to the sender) until it reaches the first router DREQ to every router on the path (from itself to the sender) until it
that belongs to the path from the sender to the LAST-HOP. reaches the first router that belongs to the path from the sender to
the LAST-HOP.
The second problem is that traceroute provides the path from the The second problem is that traceroute provides the path from the
requester to the sender which, due to routing asymmetries, may be dif- requester to the sender which, due to routing asymmetries, may be
ferent than the path traffic from the sender to the LAST-HOP uses. There different than the path traffic from the sender to the LAST-HOP uses.
is (at least) one case where this asymmetry will cause the diagnosis to There is (at least) one case where this asymmetry will cause the
fail. We present this case below. diagnosis to fail. We present this case below.
Downstream Path Sender Downstream Path Sender
__ __ __ __ __ __ __ __
Receiver +------| |<------| |<-- ...---| |-----| | Receiver +------| |<------| |<-- ...---| |-----| |
__ __ / |__| |__| |__| |__| __ __ / |__| |__| |__| |__|
| |--....--|X |_/ ^ | |--....--|X |_/ ^
|__| |__| \ Router B | |__| |__| Router B |
Black \ __ | Black __ |
Hole +----->| |---->---+ Hole +----->| |---->---+
|__| Upstream Path |__| Upstream Path
Router A Router A
Figure 2 Figure 2
Here the first hop upstream of the black hole is different on the Here the first hop upstream of the black hole is different on the
upstream path and the downstream path. Traceroute will indicate router A upstream path and the downstream path. Traceroute will indicate
as the previous hop (instead of router B which is the right one). Send- router A as the previous hop (instead of router B which is the right
ing a DREQ to router A will result in A responding with R-error 0x01 (No one). Sending a DREQ to router A will result in A responding with R-
PATH State). If the two paths converge again then the requester can use error 0x01 (No PATH State). If the two paths converge again then the
the solution proposed above to get any (partial) information from the requester can use the solution proposed above to get any (partial)
rest of the path. information from the rest of the path.
We don't have, for the moment, any complete solutions for the problem- We don't have, for the moment, any complete solutions for the
atic scenarios described here. problematic scenarios described here.
6. Comments on Diagnostic Client Implementation. 6. Comments on Diagnostic Client Implementation.
Following the design principle that nodes in the network should not hold Following the design principle that nodes in the network should not
more than necessary state, RSVP nodes are responsible only for forward- hold more than necessary state, RSVP nodes are responsible only for
ing Diagnostic messages and filling DIAG_RESPONSE objects. Additional forwarding Diagnostic messages and filling DIAG_RESPONSE objects.
diagnostic functionality should be carried out by the diagnostic Additional diagnostic functionality should be carried out by the
clients. Furthermore, if the diagnostic function is invoked from a diagnostic clients. Furthermore, if the diagnostic function is
third-party host, we should not require that host be running RSVP daemon invoked from a third-party host, we should not require that host be
to perform the function. Below we sketch out the basic functions that a running an RSVP daemon to perform the function. Below we sketch out
diagnostic client daemon should carry out. the basic functions that a diagnostic client daemon should carry out.
1. Take input from the user about the session to be diagnosed, the 1. Take input from the user about the session to be diagnosed, the
last-hop and the sender address, the Max-RSVP-hops, and possibly last-hop and the sender address, the Max-RSVP-hops, and possibly
the DIAG_SELECT list, create a DREQ message and send to the LAST- the DIAG_SELECT list, create a DREQ message and send to the
HOP RSVP node using raw IP message with protocol number 46 (RSVP). LAST-HOP RSVP node using raw IP message with protocol number 46
If the user specified that the response should be sent hop-by-hop (RSVP). If the user specified that the response should be sent
include an empty ROUTE object to the DREQ message sent. Set the hop-by-hop include an empty ROUTE object to the DREQ message
Path_MTU to the smaller of the user request and the MTU of the link sent. Set the Path_MTU to the smaller of the user request and
through which the DREQ will be sent. the MTU of the link through which the DREQ will be sent.
The port of the UDP socket on which the Diagnostic Client is The port of the UDP socket on which the Diagnostic Client is
listening for replies should be included in the Requester FIL- listening for replies should be included in the Requester
TER_SPEC object. FILTER_SPEC object.
2. Set a retransmission timer, waiting for the reply (one or more DREP 2. Set a retransmission timer, waiting for the reply (one or more
messages). Listen to the specified UDP port for responses from the DREP messages). Listen to the specified UDP port for responses
LAST-HOP RSVP node. from the LAST-HOP RSVP node.
The LAST-HOP RSVP node, upon receiving DREP messages, sends them to The LAST-HOP RSVP node, upon receiving DREP messages, sends them
the the Diagnostic Client as UDP packets, using the port supplied to the Diagnostic Client as UDP packets, using the port supplied
in the Requester FILTER_SPEC object. in the Requester FILTER_SPEC object.
3. Upon receiving a DREP message to an outstanding diagnostic request, 3. Upon receiving a DREP message to an outstanding diagnostic
the client should clear the retransmission timer, check to see if request, the client should clear the retransmission timer, check
the reply contains the complete result of the requested diagnosis. to see if the reply contains the complete result of the
If so, it should pass the result up to the invoking entity immedi- requested diagnosis. If so, it should pass the result up to the
ately. invoking entity immediately.
4. Reassemble DREP fragments. If the first reply to an outstanding 4. Reassemble DREP fragments. If the first reply to an outstanding
diagnostic request contains only a fragment of the expected result, diagnostic request contains only a fragment of the expected
the client should set up a reassembly timer in a way similar to IP result, the client should set up a reassembly timer in a way
packet reassembly timer. If the timer goes off before all frag- similar to IP packet reassembly timer. If the timer goes off
ments arrive, the client should pass the partial result to the before all fragments arrive, the client should pass the partial
invoking entity. result to the invoking entity.
5. Use retransmission and reassembly timers to gracefully handle 5. Use retransmission and reassembly timers to gracefully handle
packet losses and reply fragment scenarios. packet losses and reply fragment scenarios.
In the absence of response to the first diagnostic request, a In the absence of response to the first diagnostic request, a
client should retransmit the request a few times. If all the client should retransmit the request a few times. If all the
retransmissions also fail, the client should invoke traceroute or retransmissions also fail, the client should invoke traceroute
mtrace to obtain the list of hops along the path segment to be or mtrace to obtain the list of hops along the path segment to
diagnosed, and then perform an iteration of diagnosis with increas- be diagnosed, and then perform an iteration of diagnosis with
ing hop count as suggested in Section 5.6 in order to cross RSVP- increasing hop count as suggested in Section 5.6 in order to
capable but diagnosis-incapable nodes. cross RSVP-capable but diagnosis-incapable nodes.
6. If all the above efforts fail, the client must notify the invoking 6. If all the above efforts fail, the client must notify the
entity. invoking entity.
7. Security Considerations 7. Security Considerations
RSVP Diagnostics, as any other diagnostic tool, can be a security threat RSVP Diagnostics, as any other diagnostic tool, can be a security
since it can reveal possibly sensitive RSVP state information to threat since it can reveal possibly sensitive RSVP state information
unwanted third parties. to unwanted third parties.
We feel that the threat is minimal, since as explained in the Introduc-
tion Diagnostics messages produce no side-effects and therefore they
cannot change RSVP state in the nodes. In this respect RSVP Diagnostics We feel that the threat is minimal, since as explained in the
is less a security threat than other diagnostic tools and protocols such Introduction Diagnostics messages produce no side-effects and
as SNMP. therefore they cannot change RSVP state in the nodes. In this respect
RSVP Diagnostics is less a security threat than other diagnostic
tools and protocols such as SNMP.
Furthermore, processing of Diagnostic messages can be disabled if it is Furthermore, processing of Diagnostic messages can be disabled if it
felt that is a security threat. is felt that is a security threat.
8. Acknowledgments 8. Acknowledgments
The idea of developing a diagnostic facility for RSVP was first sug- The idea of developing a diagnostic facility for RSVP was first
gested by Mark Handley of UCL. Many thanks to Lee Breslau of Xerox PARC suggested by Mark Handley of UCL. Many thanks to Lee Breslau of
and John Krawczyk of Baynetworks for their valuable comments on the Xerox PARC and John Krawczyk of Baynetworks for their valuable
first draft of this memo. Lee Breslau, Bob Braden, and John Krawczyk comments on the first draft of this memo. Lee Breslau, Bob Braden,
contributed further comments after March 1996 IETF. Steven Berson pro- and John Krawczyk contributed further comments after March 1996 IETF.
vided valuable comments on various drafts of the memo. We would also Steven Berson provided valuable comments on various drafts of the
like to acknowledge Intel for providing a research grant as a partial memo. Tim Gleeson contributed an extensive list of editorial
support for this work. Subramaniam Vincent did most of this work while a comments. We would also like to acknowledge Intel for providing a
graduate research assistant at the USC Information Sciences Institute research grant as a partial support for this work. Subramaniam
(ISI). Vincent did most of this work while a graduate research assistant at
the USC Information Sciences Institute (ISI).
9. References 9. References
[RSVP] Braden, R. Ed. et al, "Resource ReserVation Protocol -- Version 1 [RSVP] Braden, R. Ed. et al, "Resource ReserVation Protocol --
Functional Specification", RFC 2205, September 1997. Version 1 Functional Specification", RFC 2205, September 1997.
[RSVPTUN] A. Terzis, J. Krawczyk, J. Wroclawski, L. Zhang. "RSVP Opera- [RSVPTUN] A. Terzis, J. Krawczyk, J. Wroclawski, L. Zhang. "RSVP
tion Over IP Tunnels ", Internet Draft. draft-ietf-rsvp-tunnel-02.txt, Operation Over IP Tunnels ", Internet Draft. draft-ietf-rsvp-tunnel-
February, 1999. 02.txt, February, 1999.
10. Authors' Addresses 10. Authors' Addresses
Andreas Terzis Andreas Terzis
UCLA UCLA
4677 Boelter Hall 4677 Boelter Hall
Los Angeles, CA 90095 Los Angeles, CA 90095
Phone: 310-267-2190 Phone: 310-267-2190
Email: terzis@cs.ucla.edu Email: terzis@cs.ucla.edu
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