Huawei AR1200 series Configuration Manual page 87

Huawei AR1200 Series Enterprise Routers
Configuration Guide - VPN
Issue 01 (2012-04-20)
7. (Optional) When the direct route of the local CE needs to be imported to the VPN
routing table (for being advertised to the remote PE), you can choose either of the
following configurations:
– Run the import-route direct [ med med | route-policy route-policy-name ]*
command to import the direct routes of the local CE into the VPN routing table.
– Run the network ipv4-address [ mask | mask-length ] [ route-policy route-policy-
name ] command to import a specific direct route of the local CE into the VPN
routing table.
NOTE
The PE can automatically learn the direct route destined for the local CE, and the learned
direct route has a higher priority than the direct route that is advertised by the local CE
based on EBGP. Therefore, if this step is not configured, the PE cannot advertise the direct
route to the remote PE based on MP-BGP.
8. (Optional) Run:
peer { group-name | ipv4-address } soo site-of-origin
The Site of Origin (SoO) attribute is configured for the specified CE.
When multiple CEs in a VPN site access different PEs, VPN routes sent from CEs to
PEs may return to this VPN site after traveling through the backbone network. This
may cause routing loops in the VPN site.
After the SoO attribute is configured on a PE, the PE adds the SoO attribute to the
route sent from a CE and advertises the route to other PE peers. Before advertising
the VPN route to the connected CE, the PE peers check the SoO attribute carried in
the VPN route. If the PE peers find that this SoO attribute is the same as the locally
configured SoO attribute, the PE peers do not advertise this VPN route to the connected
CE.
9. (Optional) Run:
peer ip-address allow-as-loop [ number ]
The loop is allowed.
This step is optional and used in the Hub and Spoke networking.
Generally, BGP uses the AS number to detect a loop. In the Hub and Spoke
networking, however, if EBGP runs between the PE and CE at the Hub site, the Hub-
PE carries the local AS number when advertising routes to the Hub-CE. Therefore,
the PE denies the subsequent routing update from the Hub-CE. To ensure the correct
transmission of routes in the Hub and Spoke networking, configure all the BGP peers
along the path, used for the Hub-CE to advertise private network routes to the Spoke-
CE and to accept the routes with the AS number repeated once.
10. (Optional) Run:
peer ip-address substitute-as
The AS number substitution is enabled for BGP.
This step is used for the networking scenario in which physically-dispersed CEs use
the same AS number. The configuration is performed on the PE.
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3 BGP MPLS IP VPN Configuration
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