Configuring The As_Path Attribute - HP FlexFabric 12900E Series Configuration Manual

Step
3. Specify the router as the next
hop for routes sent to a peer
or peer group.

Configuring the AS_PATH attribute

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 unicast/multicast address family):
Step
1. Enter system view.
2. Enter BGP IPv4 unicast
address
BGP-VPN
address family view, or BGP
IPv4 multicast address family
view.
3. Permit the local AS number
to appear in routes from a
peer or peer group and set
the appearance times.
Command
peer { group-name | ipv6-address
[ prefix-length ] } next-hop-local
Command
system-view
•
Enter
address family view:
a. bgp
b. address-family
•
Enter BGP-VPN IPv4 unicast
address family view:
c. bgp
family view,
IPv4 unicast
d. ip
e. address-family
•
Enter BGP IPv4 multicast
address family view:
f. bgp
g. address-family
peer { group-name | ipv4-address
[ mask-length ] } allow-as-loop
[ number ]
BGP IPv4 unicast
as-number
[ instance
instance-name
[ multi-session-thread ]
ipv4
[ unicast ]
as-number
[ instance
instance-name
[ multi-session-thread ]
vpn-instance
vpn-instance-name
ipv4
[ unicast ]
as-number
[ instance
instance-name
[ multi-session-thread ]
ipv4
multicast
250
Remarks
By default, the router sets itself as
the next hop for routes sent to an
EBGP peer or peer
However, it does not set itself as
the next hop for routes sent to an
IBGP peer or peer group.
Remarks
N/A
]
]
N/A
]
By default, the local AS number is
not allowed in routes from a peer
or peer group.
group.