Avaya 8800 Configuration Manual page 29

Circuitless IP
Figure 10: Routers with IBGP connections
CLIP 1 and CLIP 2 represent the virtual CLIP addresses that are configured between R1 and
R2. These virtual interfaces are not associated with the physical link or hardware interface.
The IBGP session can continue as long as a path exists between R1 and R2. An IGP (such
as OSPF) is used to route addresses corresponding to the CLIP addresses. After the routers
in the AS learn all the CLIP addresses, the IBGP is established and routes can be
exchanged.
The CLIP interface is treated as any other IP interface. The network associated with the CLIP
is treated as a local network attached to the device. This route always exists and the circuit is
always up because no physical attachment exists.
Routes are advertised to other routers in the domain either as external routes using the route
redistribution process or when you enable OSPF in a passive mode to advertise an OSPF
internal route. You can configure the OSPF protocol only on the circuitless IP interface.
When you create a CLIP interface, the system software programs a local route with the SF/
CPU as destID. The SF/CPU processes all packets that are destined to the CLIP interface
address. Other packets with destination addresses associated with this network (but not with
the interface address) are treated as if they are from an unknown host.
A CLIP address can be used as the source IP address in the IP header to send remote
monitoring (RMON) traps.
Configuration — OSPF and RIP June 2011 29