Huawei Quidway NetEngine80E Configuration Manual page 922

HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
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Modifying the Next_Hop
In some scenarios, the Next_Hop needs to be modified.
Next_Hop needs to be modified in specific scenarios.
Table 8-14 Next_Hop processing
Objectives
To enable an
ASBR to
modify the
Next_Hops of
the routes to be
advertised to
IBGP peers.
Issue 02 (2014-09-30)
When advertising a route to an EBGP peer, a BGP speaker sets the Next_Hop of the route
to the address of the local interface through which the BGP peer relationship is established.
When advertising a locally generated route to an IBGP peer, a BGP speaker sets the
Next_Hop of the route to the address of the local interface through which the BGP peer
relationship is established.
When advertising a route learned from an EBGP peer to an IBGP peer, the BGP speaker
does not modify the Next_Hop of the route.
Command
peer { ipv4-address |
group-name } next-
hop-local
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Table 8-14
Usage Scenarios
By default, when an ASBR
forwards a route learned
from an EBGP peer to its
IBGP peers, the ASBR
does not change the
Next_Hop of the route.
Therefore, the Next_Hop
address of the route
remains the EBGP peer IP
address. After being
forwarded to the IBGP
peers, the route cannot
become active as the
Next_Hop is unreachable.
To address this issue,
configure the ASBR to
modify the Next_Hop of
the route to the local IP
address before advertising
the route to IBGP peers.
After being forwarded to
the IBGP peers, the route
can be active because the
Next_Hop is reachable (an
IGP is configured in the
AS).
8 BGP Configuration
describes whether the
Remarks
If BGP load
balancing has been
configured using the
maximum load-
balancing number
command, the router
modifies the
Next_Hop of each
route to the local IP
address through
which the IBGP peer
relationship is
established before it
advertises the route
to IBGP peers,
regardless of whether
the peer next-hop-
local command is
configured. For
details, see 8.17
Configuring BGP
Load Balancing.
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