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caio.szekely
Beginner

Limit to connect a router to different AS's

Hi!

I have a question about the amount of autonomous systems that can be configured on a router.

Is there any limit to connect a router to different AS's? (peering)

Is there a limit to the ASR-9001 chassis? I need to connect to 6 different AS's.

Has anyone had experience using multiple AS's on a single router?

Thank you!

Caio Szekely

1 REPLY 1
Adam Vitkovsky
Participant

> I have a question about the amount of autonomous systems that can be configured on a router.

Majority of the OS-es support just one AS/bgp process per router.

 

In XR on CRS you can use "multi-instance multi-as BGP"

-it’s basically running multiple separate "complete BGP process suites" on a single RP or on multiple DRPs.

Not to be mistaken with "distributed BGP" where only "BGP speaker process" could be distributed among multiple DRPs.

It has to be configured manually via cmd: router bgp 123 instance <instance_name>.

And XR should respond back that it's starting a separate process.

IPv4 AFs have to be configured under one instance same applies for IPv6 AFs and Multicast related AFs, VPNv4 and VPNv6 AFs can be configured in multiple instances.

 

 

> Is there any limit to connect a router to different AS's? (peering)

Only in terms of routes received from those peers

 

> Is there a limit to the ASR-9001 chassis? I need to connect to 6 different AS's.

For that you just need one AS –no need for multiple AS-es

If you only need to act as a different AS# for a particular eBGP or even iBGP peer, you might use the "local-as" feature.

Or if you would like to achieve more separation you might be looking at the "route-server-context" feature and prepend desired AS# manually via route-map (available only in IOS XE).

 

adam

 

netconsultings.com

::carrier-class solutions for the telecommunications industry::

 

adam