HP VPN Firewall Appliances Network Management Configuration Guide

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If a BGP router has two peers on a common broadcast network, it does not set itself as the next hop for
routes sent to an EBGP peer by default. As shown in Figure 296, Router A and Router B establish an EB
GP
neighbor relationship, and Router B and Router C establish an IBGP neighbor relationship. They are on
the same broadcast network 1.1.1.0/24. When Router B sends EBGP routes to Router A, it does not set
itself as the next hop by default. However, you can configure Router B to set it as the next hop (1.1.1.2/24)
for routes sent to Router A by using the peer next-hop-local command as needed.
Figure 296 NEXT_HOP attribute configuration
IMPORTANT:
If you have configured BGP load balancing, the router sets itself as the next hop for routes sent to an IBGP
peer or peer group regardless of whether the peer next-hop-local command is configured.
To configure the NEXT_HOP attribute:
Ste
p
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. ipv4-family vpn-instance
vpn-instance-name
Use either method.
3. Specify the router as
the next hop of routes
sent to a peer or peer
group.
peer { group-name | ip-address }
next-hop-local
Optional.
By default, the router sets it as the
next hop for routes sent to an EBGP
peer or peer group, but does not
set it as the next hop for routes sent
to an IBGP peer or peer group.
Configuring the AS_PATH attribute
1. 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 so, it discards the route to avoid routing loops.
However, in certain network environments (a Hub&Spoke network in L3VPN, for example), 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 local AS number to appear in routes from a peer or peer group and specify the
appearance times.