User's Manual

454
Command Purpose
ip access-list standard
access-list-name Define an access list.
router bgp
autonomous-system Enter into router configuration mode.
neighbor
{ip-address | peer-group-name}
distribute-list
access-list-name {
in
|
out
}
Establish a BGP filter.
Use prefix list together with global configuration command “ip prefix-list” and command “neighbour prefix-list”.
Command Purpose
ip prefix-list
prefixs-list-name ｛
permit |deny
｝
A.B.C.D/n
ge
x
le
y
Define a prefix list.
router bgp
autonomous-system
Enter into router configuration mode.
neighbor
{ip-address | peer-group-name}
prefix-list
prefix-list-name {
in | out
}
Establish a BGP filter.
Use route-map together with global configuration command “route-map” and command “neighbour route-map”.
Using route-map can not only filter routes, but also changes routes attribute, the usage will be described in the
following chapters.
For example based on neighbour filter route, please refer to “example of BGP route filtration based on the
neighbor”.
8. Configure BGP route filtration based on the interface
Configuring BGP route filtration based on the interface can be achieved through using access list and prefix
list. Network number and the gateway address of the routes can be filtered. It can designate “access-list”
option to use access list for filtration of network number of the routes, designate “prefix-list” option to use prefix
list for filtration of network number of the routes, designate “gateway” option to use access list for filtration of
“nexthop” attribute of the routes. It can even filter the network number and “nexthop” attribute of routes at the
same time, but “access-list” option cannot be used together with “prefix-list” option. Designate “*” can filter
the routes on all interfaces.
To order to configure the filtration of BGP routes based on the interface, you should carry out the following
configurations under BGP configuration mode:
Command Purpose
filter interface
｛
in | out
｝〔
access-list
access-
list-name 〕 〔
prefix-list
prefix-list-name 〕
〔
gateway
access-list-name〕
Filter BGP routes based on the interface.
For examples of route filtration based on the interface, please refer to “examples of BGP route filtration based
on the interface”.
9. Disable the nexthop treatment of BGP update
You can configure to disable the nexthop treatment of neighbour BGP update. This may be useful in non-
broadcasting network (such as FR or X.25), in FR or X.25 network, BGP neighbour may not directly access all
other neighbors in the same IP sub-network. There are two methods to cancel nexthop treatment:
(9) Use the local IP address of this BGP connection to replace the nexthop address of the
outcoming route;
(10) Use route-map to designate the nexthop address of incoming or outcoming routes. (Please
refer to other chapters)