3Com Switch 8800 Advanced Software V5 Configuration Guide

Controlling Route Distribution and Reception 439
c
CAUTION:
■ Only routes permitted by the specified filter policy can be added into the local
BGP routing table.
■ Members of a peer group can have different inbound route filter policies from
the peer group.
Enabling BGP and IGP
Route Synchronization
With this feature enabled, if a non BGP router is responsible for forwarding
packets in the AS, the BGP speaker in the AS cannot advertise routes to external
ASs unless all the routers in the AS know the latest routing information.
By default, when a BGP router receives an IBGP route, it only checks the
reachability of the route’s next hop. With BGP and IGP synchronization enabled,
the BGP router cannot advertise the route to EBGP peers unless the route is also
advertised by the IGP.
To configure BGP and IGP synchronization, use the following commands:
Filter incoming routes filter-policy { acl-number |
ip-prefix ip-prefix-name }
import
Required to choose any;
No inbound filtering is configured
by default;
You can configure a filtering policy
as needed;
If several filtering policies are
configured, they are applied in the
following sequence:
■ filter-policy import
■ peer filter-policy import
■ peer as-path-acl import
■ peer ip-prefix import
■ peer route-policy import
Only routes passing the first policy,
can they go through the next; and
only routes passing all the
configured policies, can they be
received.
Reference a routing policy to
filter routes from a peer/peer
group
peer { group-name |
ip-address } route-policy
policy-name import
Reference an ACL to filter
routing information from a
peer/peer group
peer { group-name |
ip-address } filter-policy
acl-number import
Reference an AS path ACL to
filter routing information
from a peer/peer group
peer { group-name |
ip-address } as-path-acl
as-path-acl-number
import
Reference an IP prefix list to
filter routing information
from a peer/peer group
peer { group-name |
ip-address } ip-prefix
ip-prefix-name import
Specify the maximum
number of routes that can
be received from a peer/peer
group
peer { group-name |
ip-address } route-limit
limit [ percentage ]
The number is unlimited by
default.
To do... Use the command... Remarks
To do... Use the command... Remarks
Enter system view system-view -
Enter BGP view bgp as-number -
Enable synchronization
between BGP and IGP
synchronization Required
Not enabled by default