auto-discovery inter-as

On a network with multiple autonomous systems (ASs), run the auto-discovery inter-as command to enable the auto-discovery function for inter-AS.

For the scenario configured with inter-AS Option C, the auto-discovery inter-as command is not influenced by the peer advertise-community command.

• After the auto-discovery inter-as command is deployed to a PE, the local attribute of the PE does not have the no-export limit, which means the routes are established to EBGP peers. The network can be properly connected.
• When the auto-discovery inter-as command is not configured on a PE, then the local attribute of the PE has the no-export limit, which means the routers cannot be established to EBGP peers. The network cannot work properly.
  For the scenario configured with inter-AS Option B, the auto-discovery inter-as command is influenced by the peer advertise-community command.
• If the peer advertise-community command is not configured, the peer ASBRs receive routes information without the no-export attribute, so the network can be properly connected, no matter whether the auto-discovery inter-as command is configured or not.
• After the auto-discovery inter-as command is deployed to a PE, the local attribute of the PE does not have the no-export limit, and the routes established to peer ASBRs do not contain the no-export attribute. The ASBRs can send the received routes to other EBGP peers, so the network can be properly connected.
• When the auto-discovery inter-as command is not configured on a PE, then the local attribute of the PE has the no-export limit, but the routers established to peer ASBRs do not contain the no-export attribute. The ASBRs can send the received routes to other EBGP peers, so the network can work properly.
• If the peer advertise-community command is configured, the auto-discovery inter-as command determines whether the routes established to ASBRs contains the no-export attribute or not.
• After the auto-discovery inter-as command is deployed to a PE, the local attribute of the PE does not have the no-export limit, and the routes established to peer ASBRs do not contain the no-export attribute. The ASBRs can send the received routes to other EBGP peers, so the network can be properly connected.
• When the auto-discovery inter-as command is not configured on a PE, then the local attribute of the PE has the no-export limit, the routers established to peer ASBRs also contain the no-export attribute. The ASBRs cannot send the received routes to other EBGP peers, so the network cannot work properly.