draft-ietf-ccamp-gmpls-ason-routing-ospf-00.txt   draft-ietf-ccamp-gmpls-ason-routing-ospf-01.txt 
CCAMP Working Group Dimitri Papadimitriou CCAMP Working Group Dimitri Papadimitriou
Internet Draft (Alcatel) Internet Draft (Alcatel)
Category: Standard Category: Standard
OSPFv2 Routing Protocol Extensions for ASON Routing OSPFv2 Routing Protocol Extensions for ASON Routing
draft-ietf-ccamp-gmpls-ason-routing-ospf-00.txt draft-ietf-ccamp-gmpls-ason-routing-ospf-01.txt
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). All Rights Reserved. Copyright (C) The Internet Society (2006).
Abstract Abstract
The Generalized MPLS (GMPLS) suite of protocols has been defined to The Generalized MPLS (GMPLS) suite of protocols has been defined to
control different switching technologies as well as different control different switching technologies as well as different
applications. These include support for requesting TDM connections applications. These include support for requesting TDM connections
including SONET/SDH and Optical Transport Networks (OTNs). including SONET/SDH and Optical Transport Networks (OTNs).
This document provides the extensions of the OSPFv2 Link State This document provides the extensions of the OSPFv2 Link State
Routing Protocol to meet the routing requirements for an Routing Protocol to meet the routing requirements for an
skipping to change at line 56 skipping to change at line 56
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1. Conventions used in this document 1. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
The reader is assumed to be familiar with the terminology and The reader is assumed to be familiar with the terminology and
requirements developed in [ASON-RR] and the evaluation outcomes requirements developed in [RFC4258] and the evaluation outcomes
detailed in [ASON-EVAL]. detailed in [ASON-EVAL].
2. Introduction 2. Introduction
There are certain capabilities that are needed to support the ITU-T There are certain capabilities that are needed to support the ITU-T
Automatically Switched Optical Network (ASON) control plane Automatically Switched Optical Network (ASON) control plane
architecture as defined in [G.8080]. [ASON-RR] details the routing architecture as defined in [G.8080]. [RFC4258] details the routing
requirements for the GMPLS suite of routing protocols to support the requirements for the GMPLS suite of routing protocols to support the
capabilities and functionality of ASON control planes identified in capabilities and functionality of ASON control planes identified in
[G.7715] and in [G.7715.1]. [G.7715] and in [G.7715.1].
[ASON-EVAL] evaluates the IETF Link State Routing Protocols against [ASON-EVAL] evaluates the IETF Link State Routing Protocols against
the requirements identified in [ASON-RR]. Candidate routing protocols the requirements identified in [RFC4258]. Candidate routing protocols
are IGP (OSPFv2 and IS-IS). This document details the OSPFv2 are IGP (OSPFv2 and IS-IS). This document details the OSPFv2
specifics for ASON routing. specifics for ASON routing.
ASON (Routing) terminology sections are provided in Appendix 1 and 2. ASON (Routing) terminology sections are provided in Appendix 1 and 2.
3. Reachability 3. Reachability
In order to advertise blocks of reachable address prefixes a In order to advertise blocks of reachable address prefixes a
summarization mechanism is introduced that complements the summarization mechanism is introduced that complements the
techniques described in [OSPF-NODE]. techniques described in [OSPF-NODE].
skipping to change at line 230 skipping to change at line 230
tuples of the form <signal_type (8 bits); number of unallocated tuples of the form <signal_type (8 bits); number of unallocated
timeslots (24 bits)> may optionally be incorporated in the timeslots (24 bits)> may optionally be incorporated in the
technology specific field of the ISCD TE link attribute when the technology specific field of the ISCD TE link attribute when the
switching capability field is set to TDM value. When included, switching capability field is set to TDM value. When included,
format and encoding MUST follow the rules defined in [RFC4202]. format and encoding MUST follow the rules defined in [RFC4202].
The purpose is purely informative: there is no mandatory processing The purpose is purely informative: there is no mandatory processing
or topology/traffic-engineering significance associated to this or topology/traffic-engineering significance associated to this
information. information.
In OSPF, the Interface Switching Capability Descriptor is a sub-TLV In OSPFv2, the Interface Switching Capability Descriptor is a sub-
(of type 15) of the Link TLV (of type 2). TLV (of type 15) of the Link TLV (of type 2).
5. Routing Information Scope 5. Routing Information Scope
The Ri is a logical control plane entity that is associated to a The Ri is a logical control plane entity that is associated to a
control plane "router". The latter is the source for topology control plane "router". The latter is the source for topology
information that it generates and shares with other control plane information that it generates and shares with other control plane
"routers". The Ri is identified by the (advertising) Router_ID. The "routers". The Ri is identified by the (advertising) Router_ID. The
routing protocol MUST support a single Ri advertising on behalf of routing protocol MUST support a single Ri advertising on behalf of
more than one Li. Each Li is identified by a unique TE Router ID. more than one Li. Each Li is identified by a unique TE Router ID.
Note that the Router_Address top-level TLV definition, processing
and usage remain per [RFC 3630]. This TLV specifies a stable IP
address of the advertising router that is always reachable if there
is any IP connectivity to it.
5.1 Link Advertisement (Local and Remote TE Router ID sub-TLV) 5.1 Link Advertisement (Local and Remote TE Router ID sub-TLV)
A Router_ID (Ri) advertising on behalf multiple TE Router_ID (Li's) A Router_ID (Ri) advertising on behalf multiple TE Router_ID (Li's)
creates a 1:N relationship between the Router_ID and the TE creates a 1:N relationship between the Router_ID and the TE
Router_ID. As the link local and link remote (unnumbered) ID Router_ID. As the link local and link remote (unnumbered) ID
association is not unique per node (per Li unicity), the association is not unique per node (per Li unicity), the
advertisement needs to indicate the remote Lj value and rely on the advertisement needs to indicate the remote Lj value and rely on the
initial discovery process to retrieve the [Li;Lj] relationship. In initial discovery process to retrieve the [Li;Lj] relationship. In
brief, as unnumbered links have their ID defined on per Li bases, brief, as unnumbered links have their ID defined on per Li bases,
the remote Lj needs to be identified to scope the link remote ID to the remote Lj needs to be identified to scope the link remote ID to
the local Li. Therefore, the routing protocol MUST be able to the local Li. Therefore, the routing protocol MUST be able to
D.Papadimitriou et al. - Expires December 2006 5
disambiguate the advertised TE links so that they can be associated disambiguate the advertised TE links so that they can be associated
with the correct TE Router ID. with the correct TE Router ID.
For this purpose, a new sub-TLV of the (OSPFv2 TE LSA) top level For this purpose, a new sub-TLV of the (OSPFv2 TE LSA) top level
Link TLV is introduced that defines the local and the remote Link TLV is introduced that defines the local and the remote
TE_Router_ID. TE_Router_ID.
D.Papadimitriou et al. - Expires December 2006 5
The type of this sub-TLV is 17, and length is eight octets. The The type of this sub-TLV is 17, and length is eight octets. The
value field of this sub-TLV contains four octets of Local TE Router value field of this sub-TLV contains four octets of Local TE Router
Identifier followed by four octets of Remote TE Router Identifier. Identifier followed by four octets of Remote TE Router Identifier.
The value of the Remote TE Router Identifier SHOULD NOT be set to 0. The value of the Local and the Remote TE Router Identifier SHOULD
NOT be set to 0.
The format of this sub-TLV is the following: The format of this sub-TLV is the following:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 17 | Length | | 17 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local TE Router Identifier | | Local TE Router Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote TE Router Identifier | | Remote TE Router Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This sub-TLV is optional and SHOULD only be included as part of the This sub-TLV is optional and SHOULD only be included as part of the
top level Link TLV if the Router_ID is advertising on behalf of more top level Link TLV if the Router_ID is advertising on behalf of more
than one TE_Router_ID. In any other case, this sub-TLV SHOULD be than one TE_Router_ID. In any other case, this sub-TLV SHOULD be
omitted. omitted except if operator plans to start of with 1 Li and
progressively add more Li's (under the same Ri) such as to maintain
consistency.
Note: The Link ID sub-TLV that identifies the other end of the link Note: The Link ID sub-TLV that identifies the other end of the link
(i.e. Router ID of the neighbor for point-to-point links) MUST (i.e. Router ID of the neighbor for point-to-point links) MUST
appear exactly once per Link TLV. appear exactly once per Link TLV. This sub-TLV MUST be processed as
defined in [RFC3630].
5.2 Reachability Advertisement (Local TE Router ID sub-TLV) 5.2 Reachability Advertisement (Local TE Router ID sub-TLV)
When the Router_ID advertises on behalf of multiple TE Router_IDs, When the Router_ID advertises on behalf of multiple TE Router_IDs,
the routing protocol MUST be able to associate the advertised the routing protocol MUST be able to associate the advertised
reachability information with the correct TE Router ID. reachability information with the correct TE Router ID.
For this purpose, a new sub-TLV of the (OSPFv2 TE LSA) top level For this purpose, a new sub-TLV of the (OSPFv2 TE LSA) top level
Node Attribute TLV is introduced. This TLV associates the local Node Attribute TLV is introduced. This TLV associates the local
prefixes (sub-TLV 3 and 4, see above) to a given TE Router_ID. prefixes (sub-TLV 3 and 4, see above) to a given TE Router_ID.
The type of this sub-TLV is 5, and length is four octets. The value The type of this sub-TLV is 5, and length is four octets. The value
field of this sub-TLV contains four octets of Local TE Router field of this sub-TLV contains four octets of Local TE Router
Identifier [RFC3630]. Identifier [RFC3630].
The format of this sub-TLV is the following: The format of this sub-TLV is the following:
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0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5 | Length | | 5 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local TE Router Identifier | | Local TE Router Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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This sub-TLV is optional and SHOULD only be included as part of the This sub-TLV is optional and SHOULD only be included as part of the
Node Attribute TLV if the Router_ID is advertising on behalf of more Node Attribute TLV if the Router_ID is advertising on behalf of more
than one TE_Router_ID. In any other case, this sub-TLV SHOULD be than one TE_Router_ID. In any other case, this sub-TLV SHOULD be
omitted. omitted.
6. Routing Information Dissemination 6. Routing Information Dissemination
RC disseminates downward/upward the hierarchy by re-originating this An ASON RA represents a partition of the data plane and its
routing information as Opaque TE LSA (Opaque Type 1) of LS Type 10. identifier is used within the control plane as the representation of
this partition. A RA may contain smaller RAs inter-connected by
links. The limit of the subdivision results in a RA that contains two
sub-networks interconnected by a single link. ASON RA levels do not
reflect routing protocol levels (such as OSPF areas). OSPF routing
areas containing routing areas that recursively define successive
hierarchical levels of RAs can be represented by separate instances
of the protocol.
The information that MAY be exchanged between adjacent levels RCs supporting RAs disseminate downward/upward this hierarchy. The
includes the Router_Address, Link and Node_Attribute top level TLV. vertical routing information dissemination mechanisms described in
this section do not introduce or imply a new OSPF routing area
hierarchy. RCs supporting RAs at multiple levels are structured as
separate OSPF instances with routing information exchanges between
levels described by import/export rules.
The Opaque TE LSA re-origination is governed as follows: The implication is that an RC that performs import/export of routing
- If the target interface is associated to the same area as the information as described in this document does not implement an Area
one associated with the receiving interface, the Opaque LSA MUST Border Router (ABR) functionality.
NOT be re-originated out that interface.
6.1 Import/Export Rules
RCs supporting RAs disseminate downward/upward the hierarchy by
importing/exporting this routing information as Opaque TE LSA
(Opaque Type 1) of LS Type 10. The information that MAY be exchanged
between adjacent levels includes the Router_Address, Link and
Node_Attribute top level TLV.
The Opaque TE LSA import/export rules are governed as follows:
- If the export target interface is associated to the same area as
the one associated with the import interface, the Opaque LSA MUST
NOT imported.
- If a match is found between the Advertising Router ID in the - If a match is found between the Advertising Router ID in the
header of the received Opaque TE LSA and one of the Router ID header of the received Opaque TE LSA and one of the Router ID
belonging to the area of the target interface, the Opaque LSA MUST belonging to the area of the export target interface, the Opaque
NOT be re-originated out that interface.
- If these two conditions are not met the Opaque TE LSA MAY be re-
originated.
The re-originated content MAY be transformed e.g. filtered, as long D.Papadimitriou et al. - Expires December 2006 7
as the resulting routing information is consistent. In particular, LSA MUST NOT be imported.
when more than one RC are bound to adjacent levels and both are - If these two conditions are not met the Opaque TE LSA MAY be
allowed to redistribute routing information it is expected that imported and MAY be disseminated following the OSPF flooding
these transformation are performed in consistent manner. Definition rules.
of these policy mechanisms is outside the scope of this document.
The imported/exported content MAY be transformed e.g. filtered, as
long as the resulting routing information is consistent. In
particular, when more than one RC are bound to adjacent levels and
both are allowed to import/export routing information it is expected
that these transformation are performed in consistent manner.
Definition of these policy mechanisms is outside the scope of this
document.
In practice, and in order to avoid scalability and processing In practice, and in order to avoid scalability and processing
overhead, routing information re-distributed downward/upward the overhead, routing information imported/exported downward/upward the
hierarchy is expected to include reachability information (see hierarchy is expected to include reachability information (see
Section 3) and upon strict policy control link topology information. Section 3) and upon strict policy control link topology information.
6.1 Discovery and Selection 6.2 Discovery and Selection
6.2.1 Upward Discovery and Selection
In order to discover RCs that are capable to disseminate routing In order to discover RCs that are capable to disseminate routing
information upward the routing hierarchy, the following Capability information upward the routing hierarchy, the following Capability
Descriptor bit [OSPF-CAP] are defined: Descriptor bit [OSPF-CAP] are defined:
- U bit: when set, this flag indicates that the RC is capable to - U bit: when set, this flag indicates that the RC is capable to
disseminate routing information upward the adjacent level. disseminate routing information upward the adjacent level.
In case of multiple RC are advertized with their U bit set, the RC In case of multiple RC are advertized with their U bit set, the RC
with the highest Router ID, among the RCs having set the U bit, with the highest Router ID, among the RCs having set the U bit,
SHOULD be selected as the RC for upward dissemination of routing SHOULD be selected as the RC for upward dissemination of routing
information. The other RCs MUST NOT participate in the upward information. The other RCs MUST NOT participate in the upward
dissemination of routing information as long as the opaque LSA dissemination of routing information as long as the opaque LSA
information corresponding to the highest Router ID RC does not reach information corresponding to the highest Router ID RC does not reach
D.Papadimitriou et al. - Expires December 2006 7
MaxAge. This mechanism prevents from having more than one RC MaxAge. This mechanism prevents from having more than one RC
advertizing routing information upward the routing hierarchy. advertizing routing information upward the routing hierarchy.
Note that alternatively if this information cannot be discovered Note that alternatively if this information cannot be discovered
automatically, it MUST be manually configured. automatically, it MUST be manually configured.
The same discovery - not election - mechanism is used for selecting Once an RC has been selected, it remains unmodified even if an RC
the RC taking in charge dissemination of routing information with a highest Router ID is introduced and advertizes its capability
downward the hierarchy. However, an additional restriction MUST be to disseminate routing information upward the adjacent level (i.e.
applied such that the RC selection process takes into account that U-bit set). This hysteresis mechanism prevents from disturbing the
an upper level may be adjacent to one or more lower levels. For this upward routing information dissemination process in case e.g. of
flapping.
6.2.2 Downward Discovery and Selection
The same discovery mechanism is used for selecting the RC taking in
charge dissemination of routing information downward the hierarchy.
D.Papadimitriou et al. - Expires December 2006 8
However, an additional restriction MUST be applied such that the RC
selection process takes into account that an upper level may be
adjacent to one or more lower (routing area) levels. For this
purpose a specific TLV indexing the (lower) area ID to which the purpose a specific TLV indexing the (lower) area ID to which the
RC's are capable to disseminate routing information is needed. RC's are capable to disseminate routing information is needed.
OSPF Associated Area ID TLV format carried in the OSPF router OSPF Downstream Associated Area ID TLV format carried in the OSPF
information LSA [OSPF-CAP] is defined. This TLV has the following router information LSA [OSPF-CAP] is defined. This TLV has the
format: following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Associated Area ID | | Associated Area ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// ... //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Associated Area ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type (16 bits): identifies the TLV type Type (16 bits): identifies the TLV type
Length (16 bits): length of the value field in octets Length (16 bits): length of the value field in octets
Value (32 bits): Associated Area ID whose value space is the Area ID Value (n x 32 bits): Associated Area ID whose value space is the
as defined in [RFC2328]. Area ID as defined in [RFC2328].
Note that this information MUST be present when the D bit is set. To Note that this information MUST be present when the D bit is set. To
discover RCs that are capable to disseminate routing information discover RCs that are capable to disseminate routing information
downward the routing hierarchy, the following Capability Descriptor downward the routing hierarchy, the following Capability Descriptor
bit [OSPF-CAP] is defined, that MUST be advertised together with the bit [OSPF-CAP] is defined, that MUST be advertised together with the
OSPF Area ID TLV: OSPF Downstream Associated Area ID TLV:
- D bit: when set, this flag indicates that the RC is capable to - D bit: when set, this flag indicates that the RC is capable to
disseminate routing information downward the adjacent level. disseminate routing information downward the adjacent level(s).
In case of multiple supporting RCs for the same Associated Area ID, In case of multiple supporting RCs for the same Associated Area ID,
the RC with the highest Router ID, among the RCs having set the D the RC with the highest Router ID, among the RCs having set the D
bit, MUST be selected as the RC for downward dissemination of bit, MUST be selected as the RC for downward dissemination of
routing information. The other RCs for the same Associated Area ID routing information. The other RCs for the same Associated Area ID
MUST not participate in the downward dissemination of routing MUST not participate in the downward dissemination of routing
information as long as the opaque LSA information corresponding to information as long as the opaque LSA information corresponding to
the highest Router ID RC does not reach MaxAge. This mechanism the highest Router ID RC does not reach MaxAge. This mechanism
prevents from having more than one RC advertizing routing prevents from having more than one RC advertizing routing
information downward the routing hierarchy. information downward the routing hierarchy.
Note that alternatively if this information cannot be discovered Note that alternatively if this information cannot be discovered
automatically, it MUST be manually configured. automatically, it MUST be manually configured.
D.Papadimitriou et al. - Expires December 2006 8 D.Papadimitriou et al. - Expires December 2006 9
The OSPF Router information opaque LSA (opaque type of 4, opaque ID The OSPF Router information opaque LSA (opaque type of 4, opaque ID
of 0) and its content in particular, the Router Informational of 0) and its content in particular, the Router Informational
Capabilities TLV [OSPF-CAP] and TE Node Capability Descriptor TLV Capabilities TLV [OSPF-CAP] and TE Node Capability Descriptor TLV
[OSPF-TE-CAP] MUST NOT be re-originated. [OSPF-TE-CAP] MUST NOT be re-originated.
6.2 Loop prevention 6.3 Loop prevention
When more than one RC are bound to adjacent levels of the hierarchy, When more than one RC are bound to adjacent levels of the hierarchy,
configured and selected to redistribute upward and downward the configured and selected to redistribute upward and downward the
routing information, a specific mechanism is required to avoid routing information, a specific mechanism is required to avoid
looping/re-introduction of routing information back to the upper looping/re-introduction of routing information back to the upper
level. This specific case occurs when the RC advertizing routing level. This specific case occurs e.g. when the RC advertizing
information downward the hierarchy is not the one advertizing routing information downward the hierarchy is not the one
routing upward the hierarchy (or vice-versa). advertizing routing upward the hierarchy (or vice-versa).
In all other cases, the procedure described in this section SHOULD
NOT be applied.
When these conditions are met, it is necessary to have a mean by When these conditions are met, it is necessary to have a mean by
which an RC receiving an Opaque TE LSA re-originated downward by an which an RC receiving an Opaque TE LSA imported/exported downward by
RC associated to the same area omits to re-originate back the an RC associated to the same area, omits to import/export back the
content of this LSA upward into the (same) upper level. content of this LSA upward into the (same) upper level.
6.2.1 Associated Area ID Note that configuration and operational simplification can be
obtained when both functionality are configured on a single RC (per
pair of adjacent level) fulfilling both roles. Figure 1 provides an
example where such simplification applies.
Thus we need some way of filtering the downward/onward re-originated ....................................................
Opaque TE LSA. Per [RFC2370], the information contained in Opaque . .
LSAs may be used directly by OSPF. Henceforth, by adding the Area ID . RC_5 ------------ RC_6 .
associated to the incoming routing information the loop prevention . | | .
problem can be solved. This additional information carried in opaque . | | Area Y .
LSAs including the Router Address TLV, opaque LSAs including the . ********* ********* .
Link TLV, and opaque LSAs including the Node Attribute TLV is ............* RC_1a *.........* RC_2a *.............
referred to as the Associated Area ID. * | * * | *
............* RC_1b *... ...* RC 2b *.............
. ********* . . ********* .
. | . . | .
. Area Z | . . | Area X .
. RC_3 . . RC_4 .
. . . .
........................ .........................
Figure 1. Hierarchical Environment (Example)
In this case, the procedure described in this section MAY be
omitted, as long as these conditions are permanently guaranteed. In
all other cases, without exception, the procedure described in this
section MUST be applied.
6.3.1 Associated Area ID
Thus, we need some way of filtering the downward/upward re-
originated Opaque TE LSA. Per [RFC2370], the information contained
D.Papadimitriou et al. - Expires December 2006 10
in Opaque LSAs may be used directly by OSPF. Henceforth, by adding
the Area ID associated to the incoming routing information the loop
prevention problem can be solved. This additional information that
MAY be carried in opaque LSAs including the Router Address TLV, in
opaque LSAs including the Link TLV, and in opaque LSAs including the
Node Attribute TLV, is referred to as the Associated Area ID.
The format of the Associated Area ID TLV is defined as follows: The format of the Associated Area ID TLV is defined as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Associated Area ID | | Associated Area ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type (16 bits): identifies the TLV type Type (16 bits): identifies the TLV type
Length (16 bits): length of the value field in octets Length (16 bits): length of the value field in octets
Value (32 bits): Associated Area ID whose value space is the Area ID Value (32 bits): Associated Area ID whose value space is the Area ID
as defined in [RFC2328]. as defined in [RFC2328].
6.2.2 Processing 6.3.2 Processing
D.Papadimitriou et al. - Expires December 2006 9 When fulfilling the rules detailed in Section 6.1 a given Opaque LSA
When fulfilling the rules detailed in Section 6.0 a given Opaque LSA is imported/exported downward or upward the routing hierarchy, the
is re-originated downward or upward the routing hierarchy, the
Associated Area ID TLV is added to the received opaque LSA list of Associated Area ID TLV is added to the received opaque LSA list of
TLVs such as to identify the area from where this routing TLVs such as to identify the area from where this routing
information has been received. information has been received.
When the RC adjacent to the lower or upper level routing level When the RC adjacent to the lower or upper level routing level
receives this opaque LSA, the following rule is applied (in addition receives this opaque LSA, the following rule is applied (in addition
the rule governing the re-origination of opaque LSAs as detailed in the rule governing the import/export of opaque LSAs as detailed in
Section 6.0). Section 6.1).
- If a match is found between the Associated Area ID of the received - If a match is found between the Associated Area ID of the received
Opaque TE LSA and the Area ID belonging to the area of the target Opaque TE LSA and the Area ID belonging to the area of the export
interface, the Opaque LSA MUST NOT be re-originated out that target interface, the Opaque LSA MUST NOT be imported.
interface.
- Otherwise, this opaque LSA MAY be originated downward or upward - Otherwise, this opaque LSA MAY be imported and disseminated
the routing hierarchy. downward or upward the routing hierarchy following the OSPF
flooding rules.
This mechanism ensures that no race condition occurs in the This mechanism ensures that no race condition occurs when the
following conditions for instance: conditions depicted in Figure 2 are met.
RC_5 ---------- RC_6 RC_5 ------------- RC_6
| | Area Y
| | | |
========== RC_1 ========== RC_2 ========== | | Area Y
********* *********
..........* RC_1a *.........* RC_2a *............
* | * * | *
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..........* RC_1b *.........* RC 2b *............
********* *********
| | | |
| | Area X | | Area X
RC_3 --- .. --- RC_4 RC_3 --- . . . --- RC_4
Assume that RC_1 is configured for exchanging routing information Figure 2. Race Condition Prevention (Example)
upward toward Area Y (upward the routing hierarchy) and that RC_2 is
configured for exchanging routing information toward Area X Assume that RC_1b is configured for exporting routing information
upward toward Area Y (upward the routing hierarchy) and that RC_2a
is configured for exporting routing information toward Area X
(downward the routing hierarchy). (downward the routing hierarchy).
Assumes that RC_3 advertized routing information would reach faster Assumes that routing information advertised by RC_3 would reach
to RC_4 across Area Y. faster to RC_4 across Area Y through hierarchy.
If RC_2 is not able to prevent from re-originating that information, If RC_2b is not able to prevent from importing that information,
RC_4 may receive that information before the same advertisement RC_4 may receive that information before the same advertisement
would propagate to RC_4. would propagate in Area X (from RC 3) to RC_4.
6.4 Resiliency
OSPF creates adjacencies between neighboring routers for the purpose
of exchanging routing information. After a neighbor has been
discovered, bidirectional communication is ensured, and a routing
adjacency is formed between RCs, loss of communication may result in
partitioned areas.
Consider for instance (see Figure 1.) the case where RC_1a and RC 1b
is configured for exchanging routing information downward and upward
Area Y, resp., and that RC_2a and RC_2b are not configured for
exchanging routing any routing information toward Area X. If the
communication between RC 1a and RC 2a is broken (due e.g. to RC 5 -
RC 6 communication failure), Area Y could be partitioned.
In these conditions, it is RECOMMENDED that RC 2a to be re-
configurable such as to allow for exchanging routing information
downward to Area X. This reconfiguration MAY be performed manually
or automatically using the mechanism described in Section 6.2.
Manual reconfiguration MUST be supported.
6.5 Neighbor Relationship and Routing Adjacency
It is assumed that (point-to-point) IP control channels are
provisioned/configured between RCs belonging to the same routing
level. Provisioning/configuration techniques are outside the scope
of this document.
Once established, the OSPF Hello Protocol is responsible for
establishing and maintaining neighbor relationships. This protocol
also ensures that communication between neighbors is bidirectional.
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Routing adjacency can subsequently be formed between RCs following
mechanisms defined in [RFC2328].
7. OSPFv2 Extensions 7. OSPFv2 Extensions
7.1 Compatibility 7.1 Compatibility
Extensions specified in this document are associated to the Extensions specified in this document are associated to the
Opaque TE LSA: Opaque TE LSA:
o) Router Address top level TLV (Type 1): o) Router Address top level TLV (Type 1):
- Associated Area ID sub-TLV: optional sub-TLV for loop avoidance - Associated Area ID sub-TLV: optional sub-TLV for loop avoidance
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(see Section 6.2) (see Section 6.2)
o) Link top level TLV (Type 2): o) Link top level TLV (Type 2):
- Local and Remote TE Router ID sub-TLV: optional sub-TLV for - Local and Remote TE Router ID sub-TLV: optional sub-TLV for
scoping link attributes per TE_Router ID scoping link attributes per TE_Router ID
- Associated Area ID sub-TLV: optional sub-TLV for loop avoidance - Associated Area ID sub-TLV: optional sub-TLV for loop avoidance
(see Section 6.2) (see Section 6.2)
o) Node Attribute top level TLV (Type TBD): o) Node Attribute top level TLV (Type TBD):
- Node IPv4 Local Prefix sub-TLVs: optional sub-TLV for IPv4 - Node IPv4 Local Prefix sub-TLV: optional sub-TLV for IPv4
reachability advertisement reachability advertisement
- Node IPv6 Local Prefix sub-TLVs: optional sub-TLV for IPv6 - Node IPv6 Local Prefix sub-TLV: optional sub-TLV for IPv6
reachability advertisement reachability advertisement
- Local TE Router ID sub-TLV: optional sub-TLV for scoping - Local TE Router ID sub-TLV: optional sub-TLV for scoping
reachability per TE_Router ID reachability per TE_Router ID
- Associated Area ID sub-TLV: optional sub-TLV for loop avoidance - Associated Area ID sub-TLV: optional sub-TLV for loop avoidance
(see Section 6.2) (see Section 6.3)
Opaque RI LSA: Opaque RI LSA:
o) Routing information dissemination o) Routing information dissemination
- U and D bit in Capability Descriptor TLV [OSPF-CAP] - U bit in Capability Descriptor TLV [OSPF-CAP]
- Associated Area ID TLV in the OSPF Routing Information LSA - D bit in Capability Descriptor TLV [OSPF-CAP]
[OSPF-CAP] - Downstream Associated Area ID TLV in the OSPF Routing
Information LSA [OSPF-CAP]
7.2 Scalability 7.2 Scalability
o) Routing information exchange upward/downward the hierarchy o) Routing information exchange upward/downward the hierarchy
between adjacent areas SHOULD by default be limited to reachability. between adjacent areas SHOULD by default be limited to reachability.
In addition, several transformation such as prefix aggregation are In addition, several transformation such as prefix aggregation are
recommended when allowing decreasing the amount of information re- recommended when allowing decreasing the amount of information
originated by a given RC without impacting consistency. imported/exported by a given RC without impacting consistency.
o) Routing information exchange upward/downward the hierarchy when o) Routing information exchange upward/downward the hierarchy when
involving TE attributes MUST be under strict policy control. Pacing involving TE attributes MUST be under strict policy control. Pacing
and min/max thresholds for triggered updates are strongly and min/max thresholds for triggered updates are strongly
recommended. recommended.
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o) The number of routing levels MUST be maintained under strict
policy control.
8. Acknowledgements 8. Acknowledgements
The authors would like to thank Pandian Vijay, Alan Davey and Adrian The authors would like to thank Dean Cheng, Acee Lindem, Pandian
Farrel for their useful comments and suggestions. Vijay, Alan Davey and Adrian Farrel for their useful comments and
suggestions.
9. References 9. References
9.1 Normative References 9.1 Normative References
[OSPF-NODE] R.Aggarwal, and K.Kompella, "Advertising a Router's [OSPF-NODE] R.Aggarwal, and K.Kompella, "Advertising a Router's
Local Addresses in OSPF TE Extensions," Internet Draft, Local Addresses in OSPF TE Extensions," Internet Draft,
(work in progress), draft-ietf-ospf-te-node-addr- (work in progress), draft-ietf-ospf-te-node-addr-
02.txt, March 2005. 02.txt, March 2005.
D.Papadimitriou et al. - Expires December 2006 11 [OSPF-CAP] A.Lindem et al. "Extensions to OSPF for Advertising
Optional Router Capabilities", Work in progress, draft-
ietf-ospf-cap-08.txt, November 2005.
[RFC2026] S.Bradner, "The Internet Standards Process -- [RFC2026] S.Bradner, "The Internet Standards Process --
Revision 3", BCP 9, RFC 2026, October 1996. Revision 3", BCP 9, RFC 2026, October 1996.
[RFC2328] J.Moy, "OSPF Version 2", RFC 2328, April 1998. [RFC2328] J.Moy, "OSPF Version 2", RFC 2328, April 1998.
[RFC2370] R.Coltun, "The OSPF Opaque LSA Option", RFC 2370, July [RFC2370] R.Coltun, "The OSPF Opaque LSA Option", RFC 2370, July
1998. 1998.
[RFC2740] R.Coltun et al. "OSPF for IPv6", RFC 2740, December [RFC2740] R.Coltun et al. "OSPF for IPv6", RFC 2740, December
1999. 1999.
skipping to change at line 609 skipping to change at line 740
[RFC3667] S.Bradner, "IETF Rights in Contributions", BCP 78, [RFC3667] S.Bradner, "IETF Rights in Contributions", BCP 78,
RFC 3667, February 2004. RFC 3667, February 2004.
[RFC3668] S.Bradner, Ed., "Intellectual Property Rights in IETF [RFC3668] S.Bradner, Ed., "Intellectual Property Rights in IETF
Technology", BCP 79, RFC 3668, February 2004. Technology", BCP 79, RFC 3668, February 2004.
[RFC3946] E.Mannie, and D.Papadimitriou, (Editors) et al., [RFC3946] E.Mannie, and D.Papadimitriou, (Editors) et al.,
"Generalized Multi-Protocol Label Switching Extensions "Generalized Multi-Protocol Label Switching Extensions
for SONET and SDH Control," RFC 3946, October 2004. for SONET and SDH Control," RFC 3946, October 2004.
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[RFC4202] Kompella, K. (Editor) et al., "Routing Extensions in [RFC4202] Kompella, K. (Editor) et al., "Routing Extensions in
Support of Generalized MPLS," RFC 4202, October 2005. Support of Generalized MPLS," RFC 4202, October 2005.
[RFC4203] Kompella, K. (Editor) et al., "OSPF Extensions in [RFC4203] Kompella, K. (Editor) et al., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching Support of Generalized Multi-Protocol Label Switching
(GMPLS)," RFC 4203, October 2005. (GMPLS)," RFC 4203, October 2005.
8.2 Informative References 8.2 Informative References
[ASON-EVAL] C.Hopps et al. "Evaluation of existing Routing Protocols [ASON-EVAL] C.Hopps et al. "Evaluation of existing Routing Protocols
against ASON Routing Requirements", Work in progress, against ASON Routing Requirements", Work in progress,
draft-ietf-ccamp-gmpls-ason-routing-eval-03.txt, May draft-ietf-ccamp-gmpls-ason-routing-eval-03.txt, May
2006. 2006.
[ASON-RR] D.Brungard et al. "Requirements for Generalized MPLS [OSPF-TE-CAP]J.P. Vasseur et al. , "Routing extensions for discovery
of Traffic Engineering Node Capabilities", Work in
[RFC4258] D.Brungard et al. "Requirements for Generalized MPLS
(GMPLS) Routing for Automatically Switched Optical (GMPLS) Routing for Automatically Switched Optical
Network (ASON)," RFC 4258, November 2005. Network (ASON)," RFC 4258, November 2005.
[OSPF-CAP] A.Lindem et al. "Extensions to OSPF for Advertising
Optional Router Capabilities", Work in progress, draft-
ietf-ospf-cap-08.txt, November 2005.
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[OSPF-TE-CAP]J.P. Vasseur et al. , "Routing extensions for discovery
of Traffic Engineering Node Capabilities", Work in
For information on the availability of ITU Documents, please see For information on the availability of ITU Documents, please see
http://www.itu.int http://www.itu.int
[G.7715] ITU-T Rec. G.7715/Y.1306, "Architecture and [G.7715] ITU-T Rec. G.7715/Y.1306, "Architecture and
Requirements for the Automatically Switched Optical Requirements for the Automatically Switched Optical
Network (ASON)," June 2002. Network (ASON)," June 2002.
[G.7715.1] ITU-T Draft Rec. G.7715.1/Y.1706.1, "ASON Routing [G.7715.1] ITU-T Draft Rec. G.7715.1/Y.1706.1, "ASON Routing
Architecture and Requirements for Link State Protocols," Architecture and Requirements for Link State Protocols,"
November 2003. November 2003.
skipping to change at line 657 skipping to change at line 784
November 2001 (and Revision, January 2003). November 2001 (and Revision, January 2003).
9. Author's Addresses 9. Author's Addresses
Dimitri Papadimitriou (Alcatel) Dimitri Papadimitriou (Alcatel)
Francis Wellensplein 1, Francis Wellensplein 1,
B-2018 Antwerpen, Belgium B-2018 Antwerpen, Belgium
Phone: +32 3 2408491 Phone: +32 3 2408491
EMail: dimitri.papadimitriou@alcatel.be EMail: dimitri.papadimitriou@alcatel.be
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Appendix 1: ASON Terminology Appendix 1: ASON Terminology
This document makes use of the following terms: This document makes use of the following terms:
Administrative domain: (see Recommendation G.805) for the purposes of Administrative domain: (see Recommendation G.805) for the purposes of
[G7715.1] an administrative domain represents the extent of resources [G7715.1] an administrative domain represents the extent of resources
which belong to a single player such as a network operator, a service which belong to a single player such as a network operator, a service
provider, or an end-user. Administrative domains of different players provider, or an end-user. Administrative domains of different players
do not overlap amongst themselves. do not overlap amongst themselves.
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control in a consistent manner. Management domains can be disjoint, control in a consistent manner. Management domains can be disjoint,
contained or overlapping. As such the resources within an contained or overlapping. As such the resources within an
administrative domain can be distributed into several possible administrative domain can be distributed into several possible
overlapping management domains. The same resource can therefore overlapping management domains. The same resource can therefore
belong to several management domains simultaneously, but a management belong to several management domains simultaneously, but a management
domain shall not cross the border of an administrative domain. domain shall not cross the border of an administrative domain.
Subnetwork Point (SNP): The SNP is a control plane abstraction that Subnetwork Point (SNP): The SNP is a control plane abstraction that
represents an actual or potential transport plane resource. SNPs (in represents an actual or potential transport plane resource. SNPs (in
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different subnetwork partitions) may represent the same transport different subnetwork partitions) may represent the same transport
resource. A one-to-one correspondence should not be assumed. resource. A one-to-one correspondence should not be assumed.
Subnetwork Point Pool (SNPP): A set of SNPs that are grouped together Subnetwork Point Pool (SNPP): A set of SNPs that are grouped together
for the purposes of routing. for the purposes of routing.
Termination Connection Point (TCP): A TCP represents the output of a Termination Connection Point (TCP): A TCP represents the output of a
Trail Termination function or the input to a Trail Termination Sink Trail Termination function or the input to a Trail Termination Sink
function. function.
Transport plane: provides bi-directional or unidirectional transfer Transport plane: provides bi-directional or unidirectional transfer
of user information, from one location to another. It can also of user information, from one location to another. It can also
provide transfer of some control and network management information. provide transfer of some control and network management information.
The Transport Plane is layered; it is equivalent to the Transport The Transport Plane is layered; it is equivalent to the Transport
Network defined in G.805 Recommendation. Network defined in G.805 Recommendation.
User Network Interface (UNI): interfaces are located between protocol User Network Interface (UNI): interfaces are located between protocol
controllers between a user and a control domain. Note: there is no controllers between a user and a control domain. Note: there is no
routing function associated with a UNI reference point. routing function associated with a UNI reference point.
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Appendix 2: ASON Routing Terminology Appendix 2: ASON Routing Terminology
This document makes use of the following terms: This document makes use of the following terms:
Routing Area (RA): a RA represents a partition of the data plane and Routing Area (RA): a RA represents a partition of the data plane and
its identifier is used within the control plane as the representation its identifier is used within the control plane as the representation
of this partition. Per [G.8080] a RA is defined by a set of sub- of this partition. Per [G.8080] a RA is defined by a set of sub-
networks, the links that interconnect them, and the interfaces networks, the links that interconnect them, and the interfaces
representing the ends of the links exiting that RA. A RA may contain representing the ends of the links exiting that RA. A RA may contain
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Link Resource Manager (LRM): supplies all the relevant component and Link Resource Manager (LRM): supplies all the relevant component and
TE link information to the RC. It informs the RC about any state TE link information to the RC. It informs the RC about any state
changes of the link resources it controls. changes of the link resources it controls.
Protocol Controller (PC): handles protocol specific message exchanges Protocol Controller (PC): handles protocol specific message exchanges
according to the reference point over which the information is according to the reference point over which the information is
exchanged (e.g. E-NNI, I-NNI), and internal exchanges with the RC. exchanged (e.g. E-NNI, I-NNI), and internal exchanges with the RC.
The PC function is protocol dependent. The PC function is protocol dependent.
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Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on This document and the information contained herein are provided on
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTSOR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE REPRESENTSOR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE
skipping to change at line 817 skipping to change at line 944
of such proprietary rights by implementers or users of this of such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository specification can be obtained from the IETF on-line IPR repository
at http://www.ietf.org/ipr. at http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf- this standard. Please address the information to the IETF at ietf-
ipr@ietf.org. ipr@ietf.org.
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