Dell BigIron RX Series, Руководство по настройке

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BigIron RX Series Configuration Guide 799
53-1002253-01
Filtering
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The seq <seq-value> parameter is optional and specifies the community list’s sequence number.
You can configure up to 199 entries in a community list. If you do not specify a sequence number,
the software numbers them 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.
The deny | permit parameter specifies the action the software takes if a route’s community list
matches a match statement in this ACL. To configure the community-list match statements in a
route map, use the match community command. Refer to
“Matching based on community ACL” on
page 804
The <community-num> parameter specifies the community type or community number. This
parameter can have the following values:
•
<num>:<num> – A specific community number
•
internet – The Internet community
•
no-export – The community of sub-ASs within a confederation. Routes with this community
can be exported to other sub-ASs within the same confederation but cannot be exported
outside the confederation to other ASs or otherwise sent to EBGP neighbors.
•
local-as – The local sub-AS within the confederation. Routes with this community can be
advertised only within the local subAS.
•
no-advertise – Routes with this community cannot be advertised to any other BGP4 routers at
all.
The <regular-expression> parameter specifies a regular expression for matching on community
names. For information about regular expression syntax, refer to “Using regular expressions” on
page 796. You can specify a regular expression only in an extended community ACL.
To use a community-list filter, use route maps with the match community parameter.
Defining and applying IP prefix lists
An IP prefix list specifies a list of networks. When you apply an IP prefix list to a neighbor, the device
sends or receives only a route whose destination is in the IP prefix list. The software interprets the
prefix lists in order, beginning with the lowest sequence number.
To configure an IP prefix list and apply it to a neighbor, enter commands such as the following.
BigIron RX(config)# ip prefix-list Routesfor20 permit 20.20.0.0/24
BigIron RX(config)# router bgp
BigIron RX(config-bgp)# neighbor 10.10.10.1 prefix-list Routesfor20 out
These commands configure an IP prefix list named Routesfor20, which permits routes to network
20.20.0.0/24. The neighbor command configures the device to use IP prefix list Routesfor20 to
determine which routes to send to neighbor 10.10.10.1. The device sends routes that go to
20.20.x.x to neighbor 10.10.10.1 because the IP prefix list explicitly permits these routes to be sent
to the neighbor.
Syntax: ip prefix-list <name> [seq <seq-value> ] [description <string> ] deny | permit
<network-addr> / <mask-bits> [ge <ge-value> ] [le <le-value> ]
The <name> parameter specifies the prefix list name. You use this name when applying the prefix
list to a neighbor.
The description <string> parameter is a text string describing the prefix list.