H3C Technologies H3C S12500 Series Switches - Manual (Page 421)

405
Defining filters
Configuration prerequisites
Before you configure this task, you must determine the following items:
• IP prefix list name
• Matching address range
• Extcommunity list sequence number
Defining an IP prefix list
Defining an IPv4 prefix list
Identified by name, an IPv4 prefix list can comprise multiple items. Each item specifies a prefix range to
match, and is identified by an index number.
An item with a smaller index number is matched first. If one item is matched, the IP prefix list is passed,
and the routing information will not go to the next item.
To define an IPv4 prefix list:
Step Command Remarks
1. Enter system view. system-view N/A
2. Define an IPv4
prefix list.
ip ip-prefix ip-prefix-name [ index index-number ]
{ deny | permit } ip-address mask-length
[ greater-equal min-mask-length ] [ less-equal
max-mask-length ]
Not defined by default.
If all the items are set to the deny mode, no routes can pass the IPv4 prefix list. Therefore, H3C
recommends defining the permit 0.0.0.0 0 less-equal 32 item following multiple deny items to allow
other IPv4 routing information to pass.
For example, the following configuration filters routes 10.1.0.0/16, 10.2.0.0/16, and 10.3.0.0/16, but
allows other routes to pass.
<Sysname> system-view
[Sysname] ip ipv6-prefix abc index 10 deny 10.1.0.0 16
[Sysname] ip ipv6-prefix abc index 20 deny 10.2.0.0 16
[Sysname] ip ipv6-prefix abc index 30 deny 10.3.0.0 16
[Sysname] ip ipv6-prefix abc index 40 permit 0.0.0.0 0 less-equal 32
Defining an IPv6 prefix list
Identified by name, each IPv6 prefix list can comprise multiple items. Each item specifies a prefix range
to match, and is identified by an index number.
An item with a smaller index number is matched first. If one item is matched, the IPv6 prefix list is passed,
and the routing information will not go to the next item.
To define an IPv6 prefix list: