Cisco ASA 5505 - Manual (Page 1375)

64-23
Cisco ASA 5500 Series Configuration Guide using the CLI
Chapter 64 Configuring IPsec and ISAKMP
Configuring IPsec
Crypto Map Seq_No_1
deny packets from A.3 to B
deny packets from A.3 to C
permit packets from A to B
permit packets from A to C
Crypto Map Seq_No_2
permit packets from A.3 to B
permit packets from A.3 to C
After creating the ACLs, you assign a transform set to each crypto map to apply the required IPsec to
each matching packet.
Cascading ACLs involves the insertion of deny ACEs to bypass evaluation against an ACL and resume
evaluation against a subsequent ACL in the crypto map set. Because you can associate each crypto map
with different IPsec settings, you can use deny ACEs to exclude special traffic from further evaluation
in the corresponding crypto map, and match the special traffic to permit statements in another crypto
map to provide or require different security. The sequence number assigned to the crypto ACL
determines its position in the evaluation sequence within the crypto map set.
Figure 64-2 shows the cascading ACLs created from the conceptual ACEs above. The meaning of each
symbol in the figure follows.
Crypto map within a crypto map set.
(Gap in a straight line) Exit from a crypto map when a packet
matches an ACE.
Packet that fits the description of one ACE. Each size ball
represents a different packet matching the respective ACE in the
figure. The differences in size merely represent differences in the
source and destination of each packet.
Redirection to the next crypto map in the crypto map set.
Response when a packet either matches an ACE or fails to match
all of the permit ACEs in a crypto map set.