Command Reference Guide

3Com Router 5000 Family and Router 6000 Family sham-link ● 85
Command Reference
Example Configure a sham link, with source address 1.1.1.1 and destination address 2.2.2.2.
[3Com -ospf-100-area-0.0.0.1] sham-link 1.1.1.1 2.2.2.2 cost 100
View This command can be used in the following views:
■ OSPF Area view
Description In the OSPF PE-CE connection, suppose that in an OSPF area there are two sites
belonging to the same VPN. They are connected to different PE routers and there is an
intra-domain OSPF link (backdoor) between them. Though there may be other routes
connecting the two sites via PE routers, these routes are inter-area routes, and OSPF
will first select those routes through the backdoor link. Sometimes, users desire to
select the routes first through VPN backbone. Hence it is required to establish sham
links between PE routers. In this case, the routes through VPN backbone are of the
highest priority within the OSPF area.
The sham link between VPN PE routers is taken as a link within the OSPF area. Its
source and destination addresses are both loopback interface addresses with 32-bit
mask, which must be bound to a VPN instance and imported into BGP through a
direct-connect route. The optional parameters can be appended in the
sham link
command and only those appended in the
sham link command can be selected in
the
undo command.
CAUTION:
■ The source and destination addresses of a sham link are both loopback interface
addresses with 32-bit mask, which must be bound to a VPN instance and
imported into BGP through a direct-connect route.
■ The source and destination addresses of a sham link cannot be the same.
■ The same sham link cannot be configured for different OSPF processes.
■ 50 sham links can be configured for an OSPF process at most.