Configuring Ospf Sham Links - Juniper ACX1000 Configuration Manual

ACX Series Universal Access Router Configuration Guide
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Two CE routers are linked together by a Layer 3 VPN.
These CE routers are in the same OSPF area.
An intra-area link is configured between the two CE routers.
If there is no intra-area link between the CE routers, you do not need to configure an OSPF
sham link.
For more information about OSPF sham links, see the Internet draft
draft-ietf-l3vpn-ospf-2547-01.txt, OSPF as the PE/CE Protocol in BGP/MPLS VPNs.

Configuring OSPF Sham Links

The sham link is an unnumbered point-to-point intra-area link and is advertised by means
of a type 1 link-state advertisement (LSA). Sham links are valid only for routing instances
and OSPF version 2.
Each sham link is identified by a combination of the local and remote sham link end-point
address and the OSPF area to which it belongs. Sham links must be configured manually.
You configure the sham link between two PE routers, both of which are within the same
VRF routing instance.
You need to specify the address for the local end point of the sham link. This address is
used as the source for the sham link packets and is also used by the remote PE router as
the sham link remote end-point.
The OSPF sham link's local address must be specified with a loopback address for the
local VPN. The route to this address must be propagated by BGP. Specify the address
for the local end point using the
sham-link {
local address;
}
You can include this statement at the following hierarchy levels:
[edit routing-instances routing-instance-name protocols ospf]
[edit logical-systems logical-system-name routing-instances routing-instance-name
protocols ospf]
The OSPF sham link's remote address must be specified with a loopback address for
the remote VPN. The route to this address must be propagated by BGP. To specify the
address for the remote end point, include the
sham-link-remote address <metric number>;
You can include this statement at the following hierarchy levels:
[edit routing-instances routing-instance-name protocols ospf area area-id]
[edit logical-systems logical-system-name routing-instances routing-instance-name
protocols ospf area area-id]
local option of the sham-link
sham-link-remote
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