Controlling Your BGP Routes with Communities (AS63018)

US Dedicated (AS63018) supports optional BGP communities that let you control how your prefixes are announced to our upstream transit providers. Tagging a prefix with one of the communities below changes which upstream path is preferred for inbound traffic to that prefix.

These communities are optional. If you do not tag your prefixes with any community, the default behavior applies (see below).


Our Transit Upstreams

The community scheme below controls how your prefixes are announced to each of our transit upstreams. For reference, our current transit upstream providers are:

Upstream ASN
GSL AS137409
Unitas AS13789
Cogent * AS174
Zayo * AS6461

* Montreal only. At Montreal, Cogent and Zayo are our transit upstreams (GSL and Unitas are not present). We also peer at the QIX (Quebec Internet Exchange) in Montreal for direct exchange with local networks.


What We Send You

When you establish a BGP session with AS63018, you will receive:

  • A default route (0.0.0.0/0 for IPv4 and ::/0 for IPv6)
  • Our internal routes (AS63018 prefixes)
  • Local exchange routes (prefixes from other customers on the same edge router, so you can reach them directly without transiting the public internet)

Default Behavior (no community tagged)

Your prefixes are announced to all of our transit upstreams. Our primary upstream is preferred as the inbound path, and secondary upstreams receive your prefixes with AS path prepending to act as a backup path.

In practice, this means most inbound traffic arrives via our primary upstream, and if that upstream fails or withdraws the route, traffic automatically falls back to the secondary.


Available Communities

Important: Use only one community per prefix. Do not combine traffic engineering communities on the same prefix. If multiple communities are tagged, the first matching policy takes effect and the others are ignored, which can produce unexpected results.

Community Description
63018:1374 GSL primary, Unitas backup. Sends the prefix to GSL clean and to Unitas with AS path prepending. This matches the default behavior and is provided for explicit tagging.
63018:1375 Both upstreams equally. Sends the prefix to both GSL and Unitas with no prepending. True equal-cost inbound.
63018:1376 Unitas primary, GSL backup. Sends the prefix to Unitas clean and to GSL with AS path prepending. Reverses the default preference.
63018:1378 Unitas only. Announces the prefix exclusively via Unitas. The prefix will not be sent to GSL.
63018:61378 GSL only. Announces the prefix exclusively via GSL. The prefix will not be sent to Unitas.

Default Route Communities

The default route we send to you is tagged with a community that identifies which of our upstreams it was learned from. If you are doing community-based routing on your end, you can use these to make decisions about your outbound default.

Community Description
63018:100 DEFAULT-GSL. The default route you are receiving was learned via our GSL transit.
63018:200 DEFAULT-UNITAS. The default route you are receiving was learned via our Unitas transit.

These communities are informational only — you do not need to match them unless you want to. If you want to prefer one upstream's default over the other, you can set higher local-preference on routes tagged with the corresponding community.


How to Apply a Community

Tag the community on the specific prefix in your BGP export policy toward AS63018. The exact syntax depends on your router platform. Our router will match the community on ingress and apply the corresponding export policy to our upstreams.

If a prefix is not tagged with any of the above communities, the default behavior applies.


Site Availability

Traffic engineering communities are currently available at select sites. Rollout to additional sites is planned. If your service is at a site not listed as supported, please contact support to inquire about availability or planned rollout.

Site Supported
Atlanta Coming soon
Chicago Coming soon
Dallas Coming soon
Los Angeles Coming soon
Montreal Coming soon
New York
Seattle Coming soon

Questions?

For questions about site availability, supported upstreams, or the community scheme itself, please contact support.

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