Administrator Guide
Layer 3 Routing Commands 1415
• 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.