Huawei Quidway NetEngine80E Configuration Manual page 924

HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
Objectives
To enable a
device to
modify the
Next_Hops of
BGP routes
using a route-
policy.
Obtaining a Reachable Next Hop
During route selection, BGP first checks whether the next hop addresses of routes are reachable.
Routes carrying unreachable next hop addresses are invalid and are not selected.
shows how to obtain a reachable next hop IP address or tunnel.
Issue 02 (2014-09-30)
Command
apply ip-address
next-hop{ ipv4-
address | peer-
address }
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Usage Scenarios
The Next_Hops of BGP
routes can be modified
using a route-policy in the
following situations:
l For IBGP peers, the
route-policy can be an
import or export policy.
Even if the next hop
address configured in
the route-policy is
unreachable, the IBGP
peers still add the routes
whose next hop
addresses have been
changed to the address
configured in the route-
policy to the BGP
routing table. However,
the routes are invalid.
l For EBGP peers, the
route-policy can only
be an import policy in
most cases. If the route-
policy is configured as
an export policy, the
routes whose next hop
addresses have been
changed to the address
configured in the route-
policy are discarded by
the EBGP peers
because the next hop
address is unreachable.
When the EBGP peer
relationships are
established on physical
connections, the
Next_Hops of BGP
routes cannot be
modified.
8 BGP Configuration
Remarks
If a route-policy has
been specified in the
import-route or
network command,
the apply clause
configured for the
route-policy using
the apply ip-address
next-hop command
does not take effect.
Table 8-15
899