H3C Technologies H3C S10500 Series Switches - Manual (Page 268)

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NOTE:
For inter-AS option B, two configuration methods are available:
• Do not change the next hop on an ASBR. With this method, you still need to configure MPLS LDP
between ASBRs.
• Change the next hop on an ASBR. With this method, MPLS LDP is not required between ASBRs.
The device supports only the second method. Therefore, MP-eBGP routes will get their next hops changed
by default before being redistributed to MP-iBGP. However, normal eBGP routes to be advertised to iBGP
do not have their next hops changed by default. To change the next hop to a local address, use the peer
{ ip-address | group-name } next-hop-local command. For information about the command, see Layer
3—IP Routing Configuration Guide.
Configuring inter-AS option C
Configuring the PEs
You need to establish ordinary iBGP peer relationship between PEs and ASBR PEs in an AS and
MP-eBGP peer relationship between PEs of different ASs.
The PEs and ASBR PEs in an AS must be able to exchange labeled IPv4 routes.
Follow these steps to configure a PE for inter-AS option C:
To do… Use the command… Remarks
Enter system view system-view —
Enter BGP view bgp as-number —
Configure the ASBR PE in the same
AS as the iBGP peer peer { group-name | ip-address }
as-number as-number
Required
Enable the PE to exchange labeled
IPv4 routes with the ASBR PE in the
same AS
peer { group-name | ip-address }
label-route-capability
Required
By default, the device does not
advertise labeled routes to the IPv4
peer or peer group.
Configure the PE of another AS as
the eBGP peer peer { group-name | ip-address }
as-number as-number
Required
Enter BGP-VPNv4 subaddress
family view
ipv4-family vpnv4 —
Enable the PE to exchange BGP
VPNv4 routing information with the
eBGP peer
peer { group-name | ip-address }
enable
Required
Configure the PE not to change the
next hop of a route when
advertising it to the eBGP peer
peer { group-name | ip-address }
next-hop-invariable
Optional
Required only when RRs are used
to advertise VPNv4 routes, where
the next hop of a route advertised
between RRs cannot be changed.
Configuring the ASBR PEs
In the inter-AS option C solution, an inter-AS LSP is required, and the routes advertised between the
relevant PEs and ASBRs must carry MPLS label information.