4-4
Cisco 7401ASR Installation and Configuration Guide
OL-5419-01 B0
Chapter 4 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
Step 1
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.
Step 2
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.)
Step 3
end
Exits the crypto transform configuration
mode to enabled mode.
Step 4
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.
Table 4-1
Allowed Transform Combinations
AH Transform
1
ESP Encryption Transform
1
ESP Authentication Transform
2
Transform Description
Transform
Description
Transform
Description
ah-md5-hmac
AH with MD5
(HMAC variant)
authentication
algorithm
esp-3des
ESP with 168-bit Triple
DES encryption
algorithm
esp-md5-hmac
ESP with MD5
(HMAC variant)
authentication
algorithm
