Troubleshooting guide

Hardware and Software Requirements and Limitations

The Internet connections for a multihomed router can be to the same provider or to two different providers.

Regardless, when a router has two Internet connections, the router must decide which connection to use for

certain traffic. BGP allows a router to receive different routes from the various service providers to which

it connects. Based on this information, traffic can be routed accordingly. BGP also allows a router to

advertise different networks to different neighbors. This practice keeps one link from being overused while

leaving the other idle and, therefore, ensures that your organization actually receives the benefit of the

connections for which it has paid.

Hardware and Software Requirements and Limitations

eBGP is supported in AOS products running version 8.1 or later.

iBGP is supported in AOS products running version 10.1 or later.

eBGP and iBGP are available on AOS data products as outlined in the Product Feature Matrix

(ADTRAN’s Knowledge Base article 2272).

As of AOS firmware release 18.3, the commands, organization, and configuration of BGP changed. If you

are using firmware version 18.3 or later refer to the configuration guide Configuring BGP in AOS (for

AOS data products running firmware 18.3 or later, and voice products running firmware R10.1.0 or later)

for the correct configuration information. This guide is available online at http://kb.adtran.com, article

number 3524.

When multihoming to two different service providers, it is good practice to advertise only

intended networks to prevent becoming a transit AS. Without route filtering, BGP will

advertise any BGP routes learned - including routes to service provider B, the router

learned from service provider A.

AOS devices have a 16 BGP neighbor limit. Since iBGP routers must be fully meshed, AOS

devices are only suitable for small scale iBGP applications.

Support for the full Internet forwarding information base (FIB) from two peers requires

either a NetVanta 4430 or NetVanta 5305 with 512 MB of random access memory (RAM).