Configuring the as_path attribute – H3C Technologies H3C S12500-X Series Switches User Manual

Page 232

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To configure the NEXT_HOP attribute (IPv6):

Step Command

Remarks

1.

Enter system view.

system-view

N/A

2.

Enter BGP view.

bgp as-number

N/A

3.

Enter BGP IPv6 unicast
address family view.

address-family ipv6 [ unicast ]

N/A

4.

Specify the router as the next

hop for routes sent to a peer

or peer group.

peer { group-name |
ipv6-address
} next-hop-local

By default, the router sets itself as
the next hop for routes sent to an

EBGP peer or peer group, but does

not set itself as the next hop for
routes sent to an IBGP peer or peer

group.

325B

Configuring the AS_PATH attribute

590B

Permitting local AS number to appear in routes from a peer or peer group

In general, BGP checks whether the AS_PATH attribute of a route from a peer contains the local AS

number. If yes, it discards the route to avoid routing loops.
In certain network environments (for example, a Hub&Spoke network in MPLS L3VPN), however, the
AS_PATH attribute of a route from a peer must be allowed to contain the local AS number. Otherwise, the

route cannot be advertised correctly.
To permit the local AS number to appear in routes from a peer or peer group and specify the

appearance times (IPv4):

Step Command

Remarks

1.

Enter system view.

system-view

N/A

2.

Enter BGP view or BGP-VPN
instance view.

Enter BGP view:
bgp as-number

Enter BGP-VPN instance view:

a.

bgp as-number

b.

ip vpn-instance

vpn-instance-name

N/A

3.

Enter BGP IPv4 unicast
address family view or

BGP-VPN IPv4 unicast
address family view.

address-family ipv4 [ unicast ]

N/A

4.

Permit the local AS number to

appear in routes from a peer
or peer group and specify the

appearance times.

peer { group-name | ip-address }
allow-as-loop [ number ]

By default, the local AS number is
not allowed in routes from a peer

or peer group.

To permit the local AS number to appear in routes from a peer or peer group and specify the

appearance times (IPv6):

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