The device is configured to change the next-hop address of a route to the device's own
IP address before the device advertises the route to an IBGP peer.
By default, a device does not change the next-hop address of a route when advertising
the route to an IBGP peer.
NOTE
If BGP load balancing is configured, the local switch changes the next-hop address of a route
to it's own IP address when advertising the route to IBGP peers or peer groups, regardless of
whether the peer next-hop-local command is used.
l Prevent a device from changing the next-hop address of a route imported from an IGP when
the device advertises the route to an IBGP peer.
Perform the following steps on a switch that runs BGP and has imported IGP routes:
1. Run:
system-view
The system view is displayed.
2. Run:
bgp as-number
The BGP view is displayed.
3. Run:
ipv4-family unicast
The IPv4 unicast address family view is displayed.
4. Run:
peer { ipv4-address | group-name } next-hop-invariable
The device is prevented from changing the next-hop address of a route imported from
an IGP before advertising the route to an IBGP peer.
By default, a device changes the next-hop address of a route imported from an IGP to
the address of the interface connecting the device to its peer when advertising the route
to an IBGP peer.
----End
7.4.7 Configuring AS_Path Attributes for Routes
The AS_Path attribute is used to prevent rooting loops and control route selection.
Procedure
l Allow repeated local AS numbers.
BGP uses AS numbers to detect routing loops. In Hub and Spoke networking, if EBGP
runs between a Hub-PE and a Hub-CE, the route sent from the Hub-PE to the Hub-CE
carries the AS number of the Hub-PE. After the Hub-CE sends an Update message that
contains the AS number of the Hub-PE to the Hub-PE, the Hub-PE will deny it.
To ensure proper route transmission in Hub and Spoke networking, configure all the BGP
peers on the path, along which the Hub-CE advertises private network routes to the Spoke-
CE, to accept the routes in which the local AS number repeats once.
S6700 Series Ethernet Switches
Configuration Guide - IP Routing 7 BGP Configuration
Issue 01 (2012-03-15) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
380
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