4-4
Cisco 7401ASR Installation and Configuration Guide
OL-5419-01 B0
Chapter4 Configuring the VPN Acceleration Module
Configuration Tasks
Defining Transform Sets
A transform set is a combination of security protocols and algorithms. During the IPSec security
association negotiation, peers agree to use a specific transform set to protect a particular data flow.
To define a transform set, use the following commands, starting in global configuration mode:
Table 4 -1 shows allowed transform combinations.
Command Purpose
Step1 crypto ipsec transform-set
transform-set-name transform1 [transform2
[transform3]]
Defines a transform set and enters crypto
transform configuration mode.
Note Complex rules define which entries
you can use for the transform
arguments. These rules are explained
in the command description for the
crypto ipsec transform-set
command, and Table 4 -1 provides a
list of allowed transform
combinations.
Step2 mode [tunnel | transport] Changes the mode associated with the
transform set. The mode setting is applicable
only to traffic whose source and destination
addresses are the IPSec peer addresses; it is
ignored for all other traffic. (All other traffic
is in tunnel mode only.)
Step3 end Exits the cryptotransform configuration
mode to enabled mode.
Step4 clear crypto sa
or
clear crypto sa peer {ip-address |
peer-name}
or
clear crypto sa map map-name
or
clear crypto sa spi destination-address
protocol spi
Clears existing IPSec security associations so
that any changes to a transform set take effect
on subsequently established security
associations (SAs). (Manually established
SAs are reestablished immediately.)
Using the clear crypto sa command without
parameters clears out the full SA database,
which clears out active security sessions. You
may also specify the peer, map, or entry
keywords to clear out only a subset of the SA
database.
Table4-1 Allowed Transform Combinations
AH Transform1ESP Encryption Transform1ESP Authentication Transform2
Transform Description Transform Description Transform Description
ah-md5-hmac AH with MD5
(HMACvariant)
authentication
algorithm
esp-3des ESP with 168-bit Triple
DES encryption
algorithm
esp-md5-hmac ESP with MD5
(HMAC varian t)
authentication
algorithm