Abilene BGP communities
The following represents Abilene's understanding of
its own community settings and how Abilene, STAR TAP, and CA*net3 set and
receive communities of peer networks with respect to each other.
Abilene, CA*net3, and STAR TAP set BGP communities to
indicate prefixes' status and exchange prefixes with each other as described
in the ITN program description set forth at
http://international.internet2.edu/intl_connect/index.html#itn
www.ucaid.edu/abilene/html/itnservice.html
. Abilene advertises to STAR TAP and CA*net3 all of its ITN-peer
prefixes; CA*net3 and STAR TAP advertise to Abilene only those ITN-peer
prefixes from networks which have MoUs with Abilene.
Abilene community values are set (additively) for a
given prefix. See "show ip bgp <prefix>" in the Abilene router
proxy for real-world examples.
Abilene-connected Gigapops and connectors with heterogeneous
participants (i.e. not all are universities) may need to use these communities
to help them pass prefixes appropriately to their participants. For
example, connectors can pass all prefixes on to their university participants,
but should not pass commercial or US Fednet prefixes to their commercial
or Fednet participants.
Beginning in February 2002, Abilene allows its peers
to use communities to influence Abilene's preference-setting for prefixes.
See table 2 below for details.
| community value |
community name |
description |
prefixes passed to non-ITN peer nets |
prefixes passed to ITN peer nets |
prefixes passed to connectors |
prefixes passed to commercial participants |
11537:40/160
|
FED/ITN-pref (see below)
|
Influence local-pref
|
as usual
|
as usual
|
as usual
|
as usual
|
11537:140/260
|
Connector-pref (see below)
|
Influence local-pref
|
as usual |
as usual |
as usual |
as usual |
11537:600
|
IPv6 special (see below)
|
V6 prefixes learned via tunnels
|
YES
|
YES
|
YES
|
YES
|
| 11537:902 |
SPONSORED |
non-UCAID R&E sites sponsored for connection by members |
YES
|
YES
|
YES
|
YES
|
| 11537:910 |
Abilene SEGP |
sponsored educational groups (primarily state networks) |
YES
|
YES
|
YES
|
YES
|
11537:911
|
Black Hole (see below)
|
Traffic to these prefixes will be discarded
|
no |
no
|
no
|
no
|
| 11537:950 |
Abilene_DC |
all Abilene connected participants
|
YES
|
YES
|
YES
|
YES
|
| 11537:2000 |
COMMERCIAL |
commercial research-lab participant |
YES
|
YES
|
YES
|
no
|
11537:2001
|
COMMERCIAL-PEER
|
This prefix from a *peer network*, not a regular Abilene participant, is commercial. Examples may be AUP-free prefixes accepted for ipv6 or multicast peering.
|
11537:2002
|
BLOCK-TO-COMMERCIAL
|
Connectors may set this community for prefixes they pass to Abilene. Abilene will not advertise prefixes with this community to commercial peers.
|
YES
|
YES
|
YES
|
no
|
| 11537:2500 |
nonTRANSIT |
non-ITN (and non-US) peer network |
no
|
no
|
YES
|
YES
|
| 11537:2501 |
TRANSIT |
ITN(non-US) peer network |
no
|
YES
|
YES
|
YES
|
| 11537:3000 |
FEDNET |
US federal peer network |
no
|
no
|
YES
|
YES
|
11537:3500
|
CONNECTOR-ONLY
|
Abilene uses this to mark prefixes sent to connectors but not peers
|
no
|
no
|
YES
|
YES
|
Using BGP communities to influence
Abilene's local-preference setting:
(these settings may be used for ipv4 or ipv6)
Beginning February 2002, Abilene's BGP peers may set BGP communities to
influence Abilene's setting of its local-preference for the prefixes we receive
from you. The community may cause the preference to be lower or higher
than the default preferences, and may be useful in cases where we peer with
you in more than one place and you want to influence our choice of paths
to you. Refer to the table below for the community to use and its result.
For example, if you are an Abilene connector, the default local-pref
for the prefixes we receive from you is set to 200. If you set a community
11537:260 for some prefixes, Abilene will set the local-pref for that path to
those prefixes at 260. Note: only the communities specified
below are supported.
|
|
Default
|
High
|
Low
|
Abilene CONNECTORS
set community to:
... and Abilene's local-pref for the associated prefixes will be:
|
(none)
200
|
11537:260
260
|
11537:140
140
|
Abilene ITN/nonITN/FEDNET
peers set community to:
... and Abilene's local-pref for the associated prefixes will be:
|
(none)
100
|
11537:160
160
|
11537:40
40
|
IPv6 special community: beginning November
2002, Abilene began setting a new community, 11537:600, to indicate
that prefixes with this community come to Abilene through a tunneled interface.
"Black Hole” community:
beginning November 2004, connectors may set a community to
communicate to Abilene that traffic to designated prefixes should
be blackholed within Abilene. This is to allow some protection in
DoS attacks. Connectors may only set this for their own prefixes.
This page was last edited 16 December 2004. It
can be found among the engineering documents within the Abilene NOC pages
at www.abilene.iu.edu
.
Comments: webmaster
|
