50 ServerIron ADX Security Guide
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How ServerIron processes ACLs
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Backwards compatibility option:
You can use the ip flow-based-acl-enable command to provide backwards compatibility for IPv4
ACL processing. If this command is configured, Layer 4 - 7 traffic, packets are processed in
hardware and then forwarded to the BPs where the BPs also process the ACLs. This command
is configured as shown in the following.
ServerIronADX(config)# ip flow-based-acl-enable
Syntax: ip flow-based-acl-enable
Rule-based ACLs
Some Brocade devices process the traffic that ACLs filter in hardware. This document refers to this
type of ACLs as rule-base d ACLs. These ACLs are programmed into hardware at startup or as a new
ACL is entered.
Rule-based ACLs program the ACL entries you assign to an interface into Content Addressable
Memory (CAM) space allocated for the port(s). Devices that use rule-based ACLs program the ACLs
into the CAM entries and use these entries to permit or deny packets in the hardware, without
sending the packets to the CPU for processing.
Rule-based ACLs are supported on physical interfaces, ve interfaces, trunk groups, and VIPs.
To configure a standard ACL and apply it to VIP, enter the following commands.

Configuration guidelines for rule-based ACLs: general guidelines

Consider the following guidelines:
•Rule-based ACLs support only one ACL per port. The ACL of course can contain multiple entries
(rules). For example, rule-based ACLs do not support ACLs 101 and 102 on port 1, but
rule-based ACLs do support ACL 101 containing multiple entries.
•If you change the content of an ACL (add, change, or delete entries), you must remove and then
reapply the ACL to all the ports that use it. Otherwise, the older version of the ACL remains in
the CAM and continues to be used. You can easily re-apply ACLs using the ip rebind-acl <num>
| <name> | all command. Refer to “Applying an ACLs to interfaces” on page69.
NOTE
Brocade recommends that you also remove and reapply a changed ACL.
•ACL statistics are not supported with rule-based rate limiting.
•If you use the <icmp-type> parameter with an extended ACL, the device uses the CPU to filter
packets using the ACL. The CPU is required to filter the ICMP message type.
•You can use PBR and rule-based ACLs on the same port. However, Brocade recommends that
you use exactly the same ACL for each feature. Otherwise, it is possible for the ACL’s Layer 4
CAM entry to be programmed incorrectly and give unexpected results.
ServerIronADX(config)# access-list 1 deny host 209.157.22.26
ServerIronADX(config)# access-list 1 deny 209.157.29.12
ServerIronADX(config)# access-list 1 deny host IPHost1
ServerIronADX(config)# access-list 1 permit any
ServerIronADX 1000(config)#server virtual-name-or-ip vs-80
ServerIronADX 1000(config-vs-vs-80)#acl-id 1
ServerIronADX 1000(config-vs-vs-80)#write memory