draft-ietf-grow-collection-communities-05.txt   draft-ietf-grow-collection-communities-06.txt 
INTERNET-DRAFT D. Meyer INTERNET-DRAFT D. Meyer
draft-ietf-grow-collection-communities-05.txt draft-ietf-grow-collection-communities-06.txt
Category Best Current Practice Category Best Current Practice
Expires: March 2005 September 2004 Expires: March 2005 September 2004
BGP Communities for Data Collection BGP Communities for Data Collection
<draft-ietf-grow-collection-communities-05.txt> <draft-ietf-grow-collection-communities-06.txt>
Status of this Memo Status of this Memo
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all This document is an Internet-Draft and is subject to all
provisions of section 3 of RFC 3667. By submitting this provisions of section 3 of RFC 3667. By submitting this
Internet-Draft, each author represents that any applicable Internet-Draft, each author represents that any applicable
patent or other IPR claims of which he or she is aware have patent or other IPR claims of which he or she is aware have
been or will be disclosed, and any of which he or she become been or will be disclosed, and any of which he or she become
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Internet-Drafts as reference material or to cite them other Internet-Drafts as reference material or to cite them other
than as "work in progress." than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed The list of Internet-Draft Shadow Directories can be accessed
at http://www.ietf.org/shadow.html. at http://www.ietf.org/shadow.html.
This document is a product of the GROW WG. Comments should be This document is a product of the GROW WG. Comments should be
addressed to the authors, or the mailing list at addressed to the author, or the mailing list at
grow@lists.uoregon.edu. grow@lists.uoregon.edu.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract Abstract
BGP communities (RFC 1997) are used by service providers for many BGP communities (RFC 1997) are used by service providers for many
purposes, including tagging of customer, peer, and geographically purposes, including tagging of customer, peer, and geographically
originated routes. Such tagging is typically used to control the originated routes. Such tagging is typically used to control the
scope of redistribution of routes within a provider's network, and to scope of redistribution of routes within a provider's network, and to
its peers and customers. With the advent of large scale BGP data its peers and customers. With the advent of large scale BGP data
collection (and associated research), it has become clear that the collection (and associated research), it has become clear that the
information carried in such communities is essential for a deeper information carried in such communities is essential for a deeper
understanding of the global routing system. This document defines understanding of the global routing system. This memo defines
standard (outbound) communities and their encodings for export to BGP standard (outbound) communities and their encodings for export to BGP
route collectors. route collectors.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Peers and Peering . . . . . . . . . . . . . . . . . . . . . 5 2.1. Peers and Peering . . . . . . . . . . . . . . . . . . . . . 5
2.2. Customer Routes . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Customer Routes . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Peer Routes . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Peer Routes . . . . . . . . . . . . . . . . . . . . . . . . 5
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such as LOCAL_PREF [RFC1771] by sending appropriate communities to such as LOCAL_PREF [RFC1771] by sending appropriate communities to
their service provider. Other applications include signaling various their service provider. Other applications include signaling various
types of VPNs (e.g., VPLS [VPLS]), and carrying link bandwidth for types of VPNs (e.g., VPLS [VPLS]), and carrying link bandwidth for
traffic engineering applications [EXTCOMM]. traffic engineering applications [EXTCOMM].
With the advent of large scale BGP data collection [RIS,ROUTEVIEWS] With the advent of large scale BGP data collection [RIS,ROUTEVIEWS]
(and associated research), it has become clear that the geographical (and associated research), it has become clear that the geographical
and topological information, as well as the relationship the provider and topological information, as well as the relationship the provider
has to the source of a route (e.g., transit, peer, or customer), has to the source of a route (e.g., transit, peer, or customer),
carried in such communities is essential for a deeper understanding carried in such communities is essential for a deeper understanding
of the global routing system. This document defines standard of the global routing system. This memo defines standard communities
communities for export to BGP route collectors. These communities for export to BGP route collectors. These communities represent a
represent a significant part of information carried by service significant part of information carried by service providers as of
providers as of this writing, and as such could be useful for this writing, and as such could be useful for internal use by service
internal use by service providers. However, such use is beyond the providers. However, such use is beyond the scope of this memo.
scope of this memo. Finally, those involved in BGP data analysis are Finally, those involved in BGP data analysis are encouraged to verify
encouraged to verify with their data sources as to which peers with their data sources as to which peers implement this scheme (as
implement this scheme (as there is a large amount of existing data as there is a large amount of existing data as well as many legacy
well as many legacy peerings). peerings).
The remainder of this document is organized as follows. Section 2 The remainder of this memo is organized as follows. Section 2
provides both the definition of terms used as well as the semantics provides both the definition of terms used as well as the semantics
of the communities used for BGP data collection, and section 3 of the communities used for BGP data collection, and section 3
defines the corresponding encodings for RFC 1997 [RFC1997] defines the corresponding encodings for RFC 1997 [RFC1997]
communities. Finally, section 4 defines the encodings for use with communities. Finally, section 4 defines the encodings for use with
extended communities [EXTCOMM]. extended communities [EXTCOMM].
2. Definitions 2. Definitions
In this section, we define the terms used and the categories of In this section, we define the terms used and the categories of
routes that may be tagged with communities. This tagging is often routes that may be tagged with communities. This tagging is often
referred to coloring, and we refer to a route's "color" as its refered to as coloring, and we refer to a route's "color" as its
community value. The categories defined here are loosely modeled on community value. The categories defined here are loosely modeled on
those described in [WANG] and [HUSTON]. those described in [WANG] and [HUSTON].
2.1. Peers and Peering 2.1. Peers and Peering
Consider two network service providers, A and B. Service providers A Consider two network service providers, A and B. Service providers A
and B are defined to be peers when (i). A and B exchange routes via and B are defined to be peers when (i). A and B exchange routes via
BGP, and (ii). traffic exchange between A and B is settlement-free. BGP, and (ii). traffic exchange between A and B is settlement-free.
This arrangement is also typically known as "peering". Peers This arrangement is also typically known as "peering". Peers
typically exchange only their respective customer routes (see typically exchange only their respective customer routes (see
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This mandates use of regional routing, including community attributes This mandates use of regional routing, including community attributes
set by the network in question to allow easy discrimination among set by the network in question to allow easy discrimination among
regional routes. For example, service providers may treat a route set regional routes. For example, service providers may treat a route set
received from another service provider in Europe differently than the received from another service provider in Europe differently than the
same route set received in North America, as it is common practice to same route set received in North America, as it is common practice to
sell transit in one region while peering in the other. sell transit in one region while peering in the other.
3. RFC 1997 Community Encoding and Values 3. RFC 1997 Community Encoding and Values
In this section we provide RFC 1997 [RFC1997] community values for In this section we provide RFC 1997 [RFC1997] community values for
the categories described above. RFC 1997 communities encoded as BGP the categories described above. RFC 1997 communities are encoded as
Type Code 8, and are treated as 32 bit values ranging from 0x0000000 BGP Type Code 8, and are treated as 32 bit values ranging from
through 0xFFFFFFF. The values 0x0000000 through 0x0000FFFF and 0x0000000 through 0xFFFFFFF. The values 0x0000000 through 0x0000FFFF
0xFFFF0000 through 0xFFFFFFFF are reserved. and 0xFFFF0000 through 0xFFFFFFFF are reserved.
The best current practice among service providers is to use the high The best current practice among service providers is to use the high
order two octets to represent the providers AS number, and the low order two octets to represent the provider's AS number, and the low
order two octets to represent the classification of the route, as order two octets to represent the classification of the route, as
depicted below: depicted below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| <AS> | <Value> | | <AS> | <Value> |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where <AS> 16 bit AS number. For example, the encoding 0x2A7C029A where <AS> is the 16 bit AS number. For example, the encoding
would represent the AS 10876 with value 666. 0x2A7C029A would represent the AS 10876 with value 666.
3.1. Community Values for BGP Data Collection 3.1. Community Values for BGP Data Collection
In this section we define the RFC 1997 community encoding for the In this section we define the RFC 1997 community encoding for the
route types described above for use in BGP data collection. It is route types described above for use in BGP data collection. It is
anticipated that a service provider's internal community values will anticipated that a service provider's internal community values will
be converted to these standard values for output to a route be converted to these standard values for output to a route
collector. collector.
This document follows the best current practice of using the basic This memo follows the best current practice of using the basic format
format <AS>:<Value>. The values for the route categories are <AS>:<Value>. The values for the route categories are described in
described in the following table: the following table:
Category Value Category Value
=============================================================== ===============================================================
Reserved <AS>:0000000000000000 Reserved <AS>:0000000000000000
Customer Routes <AS>:0000000000000001 Customer Routes <AS>:0000000000000001
Peer Routes <AS>:0000000000000010 Peer Routes <AS>:0000000000000010
Internal Routes <AS>:0000000000000011 Internal Routes <AS>:0000000000000011
Internal More Specific Routes <AS>:0000000000000100 Internal More Specific Routes <AS>:0000000000000100
Special Purpose Routes <AS>:0000000000000101 Special Purpose Routes <AS>:0000000000000101
Upstream Routes <AS>:0000000000000110 Upstream Routes <AS>:0000000000000110
Reserved <AS>:0000000000000111- Reserved <AS>:0000000000000111-
<AS>:0000011111111111 <AS>:0000011111111111
National and Regional Routes <AS>:0000100000000000- National and Regional Routes <AS>:0000100000000000-
<AS>:1111111111111111 <AS>:1111111111111111
Africa (AF) <AS>:<R><X><CC> Encoded as <AS>:<R><X><CC>
Oceania (OC) <AS>:<R><X><CC> Reserved National and Regional values <AS>:0100000000000000-
Asia (AS) <AS>:<R><X><CC>
Antarctica (AQ) <AS>:<R><X><CC>
Europe (EU) <AS>:<R><X><CC>
Latin America/Caribbean islands (LAC) <AS>:<R><X><CC>
North America (NA) <AS>:<R><X><CC>
Reserved <AS>:0100000000000000-
<AS>:1111111111111111 <AS>:1111111111111111
Where Where
<AS> is the 16-bit AS <AS> is the 16-bit AS
<R> is the 5-bit Region Identifier <R> is the 5-bit Region Identifier
<X> is the 1-bit satellite link indication <X> is the 1-bit satellite link indication
X = 1 for satellite links, 0 otherwise X = 1 for satellite links, 0 otherwise
<CC> is the 10-bit ISO-3166-2 country code <CC> is the 10-bit ISO-3166-2 country code
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x00 | Sub-Type | Global Administrator | | 0x00 | Sub-Type | Global Administrator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Administrator | | Local Administrator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The two-octet AS specific extended community attribute encodes the The two-octet AS specific extended community attribute encodes the
service provider's two octet Autonomous System number (as assigned by service provider's two octet Autonomous System number (as assigned by
an Regional Internet Registry, or RIR) in the Global Administrator a Regional Internet Registry, or RIR) in the Global Administrator
field, and the Local Administrator field may encode any information. field, and the Local Administrator field may encode any information.
This document assigns Sub-Type 0x05 for BGP data collection, and This memo assigns Sub-Type 0x05 for BGP data collection, and
specifies that the <Value> field, as defined in section 3.1, is specifies that the <Value> field, as defined in section 3.1, is
carried in the low order octets of the Local Administrator field. The carried in the low order octets of the Local Administrator field. The
two high order octets of the Local Administrator field are reserved, two high order octets of the Local Administrator field are reserved,
and are set to 0x00 when sending and ignored upon receipt. and are set to 0x00 when sending and ignored upon receipt.
For example, the extended community encoding for 10876:4338 For example, the extended community encoding for 10876:4338
(representing a terrestrial national route in AS 10876 from the Fiji (representing a terrestrial national route in AS 10876 from the Fiji
Islands) would be: Islands) would be:
0 1 2 3 0 1 2 3
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Note that data collection communities have the potential of making Note that data collection communities have the potential of making
the attribute set of a specific route more unique than it would be the attribute set of a specific route more unique than it would be
otherwise (since each route collects data that is specific to it's otherwise (since each route collects data that is specific to it's
path inside one or more ASes). This, in turn, can affect whether path inside one or more ASes). This, in turn, can affect whether
multiple routes can be grouped in the same BGP update message, and multiple routes can be grouped in the same BGP update message, and
may lead to increased use of bandwidth, router CPU cycles, and may lead to increased use of bandwidth, router CPU cycles, and
memory. memory.
6. Acknowledgments 6. Acknowledgments
The community encoding described in this document germinated from an The community encoding described in this memo germinated from an
interesting suggestion from Akira Kato at WIDE. In particular, the interesting suggestion from Akira Kato at WIDE. In particular, the
idea would be to use the collection community values to select paths idea would be to use the collection community values to select paths
that would result in (hopefully) more efficient access to various that would result in (hopefully) more efficient access to various
services. For example, in the case of RFC 3258 [RFC3258] based DNS services. For example, in the case of RFC 3258 [RFC3258] based DNS
anycast service, BGP routers may see multiple paths to the same anycast service, BGP routers may see multiple paths to the same
prefix, and others might be coming from the same origin with prefix, and others might be coming from the same origin with
different paths, but others might be from different region/country different paths, but others might be from different region/country
(with the same origin AS). (with the same origin AS).
Joe Abley, Randy Bush, Sean Donelan, Xenofontas Dimitropoulos, Vijay Joe Abley, Randy Bush, Sean Donelan, Xenofontas Dimitropoulos, Vijay
Gill, John Heasley, Geoff Huston, Steve Huter, Michael Patton, Gill, John Heasley, Geoff Huston, Steve Huter, Michael Patton,
Olivier Marce, Ryan McDowell, Rob Rockell, Rob Thomas, Pekka Savola, Olivier Marce, Ryan McDowell, Rob Rockell, Rob Thomas, Pekka Savola,
Patrick Verkaik and Alex Zinin all made many insightful comments on Patrick Verkaik and Alex Zinin all made many insightful comments on
early versions of this draft. Henk Uijterwaal suggested the use of early versions of this draft. Henk Uijterwaal suggested the use of
the ISO-3166-2 country codes. the ISO-3166-2 country codes.
7. Security Considerations 7. Security Considerations
While this document introduces no additional security considerations While this memo introduces no additional security considerations into
into the BGP protocol, the information contained in the communities the BGP protocol, the information contained in the communities
defined in this document may in some cases reveal network structure defined in this memo may in some cases reveal network structure that
that was not previously visible outside the provider's network. As a was not previously visible outside the provider's network. As a
result, care should be taken when exporting such communities to route result, care should be taken when exporting such communities to route
collectors. Finally, routes exported to a route collector should also collectors. Finally, routes exported to a route collector should also
be tagged with the NO_EXPORT community (0xFFFFFF01). be tagged with the NO_EXPORT community (0xFFFFFF01).
7.1. Total Path Attribute Length 7.1. Total Path Attribute Length
The communities described in this document are intended for use on The communities described in this memo are intended for use on egress
egress to a route collector. Hence an operator may choose to to a route collector. Hence an operator may choose to overwrite its
overwrite its internal communities with the values specified in this internal communities with the values specified in this memo when
document when exporting routes to a route collector. However, exporting routes to a route collector. However, operators should in
operators should in general ensure that the behavior of their BGP general ensure that the behavior of their BGP implementation is well-
implementation is well-defined when the addition of an attribute defined when the addition of an attribute causes a PDU to exceed 4096
causes a PDU to exceed 4096 octets. For example, since it is common octets. For example, since it is common practice to use community
practice to use community attributes to implement policy (among other attributes to implement policy (among other functionality such as
functionality such as allowing customers to set attributes such as allowing customers to set attributes such as LOCAL_PREF), the
LOCAL_PREF), the behavior of an implementation when the attribute behavior of an implementation when the attribute space overflows is
space overflows is crucial. Among other behaviors, an implementation crucial. Among other behaviors, an implementation might usurp the
might usurp the intended attribute data or otherwise cause intended attribute data or otherwise cause indeterminate failures.
indeterminate failures. These behaviors can result in unanticipated These behaviors can result in unanticipated community attribute sets,
community attribute sets, and hence result in unintended policy and hence result in unintended policy implications.
implications.
8. IANA Considerations 8. IANA Considerations
This document assigns a new Sub-Type for the AS specific extended This memo assigns a new Sub-Type for the AS specific extended
community type. In particular, the IANA should assign Sub-type 0x05, community type. In particular, the IANA should assign Sub-type 0x05,
using the "First Come First Served" policy defined in RFC 2434 using the "First Come First Served" policy defined in RFC 2434
[RFC2434], for the Sub-Type defined in Section 4. This corresponds to [RFC2434], for the Sub-Type defined in Section 4. This corresponds to
a Type Field value of 0x0005. a Type Field value of 0x0005.
9. References 9. References
9.1. Normative References 9.1. Normative References
[EXTCOMM] Sangali, S., D. Tappan and Y. Rekhter, "BGP Extended [EXTCOMM] Sangali, S., D. Tappan and Y. Rekhter, "BGP Extended
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