3Com 3032 Configuration Manual page 471

Defining an Access List
Entry, an AS Path-list
Entry, a Routing Policy
Table 551 Allow the Import of Network 0.0.0.0 into the BGP
Operation
Allow the import of network 0.0.0.0 into
the BGP
Disable the import of network 0.0.0.0 into
the BGP
By default, the import of network 0.0.0.0 into BGP is disabled.
This section describes the configuration of an access list, an AS path list, and a
routing policy.
Define an access list entry
See "Access Control List" in
Manual (Security Configuration)******. for more details.
Define an AS Path-list entry
There is an AS path field in the routing information packet of the BGP protocol.
When the BGP protocol operates with the switching routing information, the path
of the routing information crossing the AS is recorded in this field.
identified with aspath-list-number. When defining
an aspath regular expression used to match the aspath field in the routing
information. Use
aspath-list
information, filtering the information that does not meet the conditions. You can
define multiple aspath-lists for one list number so that one list number represents
a group of aspath-lists. Each AS path list is identified with numbers.
Perform the following configurations in system view.
Table 552 Define a BGP-related ACL Entry
Operation
Define a BGP-related ACL entry
Remove a BGP-related ACL entry
By default, no access list entry is defined.
In the matching process, many aspath-list-number us Boolean "OR" operation so
that if the routing information passes one item, information is filtered by the
as-path list identified with this list number.
Define a routing policy
A routing policy is an important way for BGP to implement the route strategy.
According to the matching result of the route attribute, BGP decides on the
operations to be applied on a route attribute. In each routing policy, there can be
several matching rules, labeled with a serial number. When importing a route, it is
compared to a rule by number, from small to large. When the first matched rule is
found, the matching process is completed. If no matched rules are found, router
reception and transmission is canceled.
Command
default-information
undo default-information
****need proper ref here 3Com Router Operation
aspath-list
to match the aspath field in the BGP routing
Command
ip as-path acl aspath-list-number {
permit | deny } as-regular-expression
undo ip as-path acl
aspath-list-number
Configuring BGP 467
is
aspath-list
, you can specify