Administrator Guide

Layer 3 Routing Commands 1409
• network mask —Specifies the match criteria for routes being compared to
the prefix list statement. The network can be any valid IP prefix. The mask
is any IPv4 prefix in dotted-quad notation.
•
ge length —(Optional) If this option is configured, a prefix is only
considered a match if its network mask length is greater than or equal to
this value. This value must be longer than the network length and less
than or equal to 32.
•
le length —(Optional) If this option is configured, a prefix is only
considered a match if its network mask length is less than or equal to this
value. This value must be longer than the ge length and less than or equal
to 32.
•
renumber —Option to renumber the sequence numbers of the ip prefix
list
statements with a given interval starting from a particular sequence
number.
Default Configuration
No prefix lists are configured by default. When neither the ge nor the le
option is configured, the destination prefix must match the network/length
exactly. If the ge option is configured without the le option, any prefix with a
network mask greater than or equal to the ge value is considered a match.
Similarly, if the le option is configured without the ge option, a prefix with a
network mask less than or equal to the le value is considered a match.
Command Mode
Global Configuration
User Guidelines
Prefix lists allow matching of route prefixes with those specified in the prefix
list. Each prefix list includes of a sequence of prefix list entries ordered by
their sequence numbers. A router sequentially examines each prefix list entry
to determine if the route’s prefix matches that of the entry. An empty or non-
existent prefix list permits all prefixes. An implicit deny is assumed if a given
prefix does not match any entries of a prefix list. Once a match or deny occurs
the router does not go through the rest of the list. A prefix list may be used
within a route map to match a route’s prefix using the match ip address
command.
2CSNXXX_SWUM204.book Page 1409 Monday, January 25, 2016 1:25 PM