Availability-Reachability tracking by SBC

In this section:

Scenario

Each SBC maintains the status of availability of peers with which it communicates.

The requirements specified in the section "Background Information and Dependencies" under Minimal Out-Of-The-Box Configuration are met.
Ports and IP Interface Groups have been configured as described in NNI: Complex route selection.
Each SBC determines independently if each peer is available based on the success of signalling requests, timeouts, reattempts etc.
At its simplest form a peer can be either alive or dead (reachable or not), in the extended case we introduce an intermediate state of "impaired". SBCs use this knowledge to make better choices about routing traffic. For an impaired peer, the traffic offered to deal with overloaded peers (for instance, using SIP 503 error message rates) is reduced. This is applicable to the network side of the ASBC/ UNI cases as well as both sides of the NNI/peering SBC cases.

Availability-Reachability tracking by SBC

SBCs 1-8 are A-SBCs.
SBC 9 & 10 are NNI/Peering SBCs.
SBCs 1-4 are configured to only send requests to AS1
SBCs 5-8 can offer requests to either AS1 or AS2
SBCs 1-8 do not offer traffic directly to each other, they only send/receive traffic from an AS
SBCs 9 & 10 can offer traffic to each other as there maybe transit calls that do not need to go to an AS
Each SBC maintains the status of availability of the peers with which it communicates.