Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 107)

Multi-Service IronWare Routing Configuration Guide 79
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Filtering
A community is an optional attribute that identifies the route as a member of a user-defined class
of routes. Community names are arbitrary values made of two five-digit integers joined by a colon.
You determine what the name means when you create the community name as a route attribute.
Each string in the community name can be a number from 0 – 65535.
This format allows you to easily classify community names. For example, a common convention
used in community naming is to configure the first string as the local AS and the second string as
the unique community within that AS. Using this convention, communities 1:10, 1:20, and 1:30
can be easily identified as member communities of AS 1.
The device provides the following methods for filtering on community information.
• Community filters - refer to “Filtering communities” on page 78.
• Community list ACLs
NOTE
The device cannot actively support community filters and community list ACLs at the same time. Use
one method or the other but do not mix methods.
NOTE
Once you define a filter or ACL, the default action for communities that do not match a filter or ACL
is deny. To change the default action to permit, configure the last filter or ACL entry as permit any
any.
Community filters or ACLs can be referred to by match clauses in a route map.
Defining a community ACL
To configure community ACL 1, enter a command such as the following. This command configures
a community ACL that permits routes that contain community 123:2.
NOTE
Refer to “Matching based on community ACL” on page 85 for information about how to use a
community list as a match condition in a route map.
Brocade(config)# ip community-list 1 permit 123:2
Syntax: [no] ip community-list standard string [seq seq-value] deny | permit community-num
Syntax: [no] ip community-list extended string [seq seq-value] deny | permit community-num |
regular-expression
The string parameter specifies the ACL name. (If you enter a number, the CLI interprets the number
as a text string.)
The standard or extended parameter specifies whether you are configuring a standard or extended
community ACL. The difference between standard and extended communities is that a standard
community ACL does not support regular expressions and an extended one does.
The seq seq-value parameter is optional and specifies the sequence number for the community
list. You can configure up to 199 entries in a community list. If you do not specify a sequence
number, the software numbers the entries in increments of 5, beginning with number 5. The
software interprets the entries in a community list in numerical order, beginning with the lowest
sequence number.