HP manual 464

Table 136 Depth-first match for ACLs

ACL category	Sequence of tie breakers
	1.	More 0s in the source IP address wildcard (more 0s means a narrower
IPv4 basic ACL		IP address range).
	2.	Smaller rule ID.
	1.	Specific protocol number.
	2.	More 0s in the source IP address wildcard mask.
IPv4 advanced ACL	3.	More 0s in the destination IP address wildcard.
	4.	Narrower TCP/UDP service port number range.
	5.	Smaller ID.
	1.	Longer prefix for the source IP address (a longer prefix means a
IPv6 basic ACL		narrower IP address range).
	2.	Smaller ID.
	1.	Specific protocol number.
	2.	Longer prefix for the source IPv6 address.
IPv6 advanced ACL	3.	Longer prefix for the destination IPv6 address.
	4.	Narrower TCP/UDP service port number range.
	5.	Smaller ID.
	1.	More 1s in the source MAC address mask (more 1s means a smaller
Ethernet frame header ACL		MAC address).
	2.	More 1s in the destination MAC address mask.
	3.	Smaller ID.

A wildcard mask, also called an "inverse mask," is a 32-bit binary and represented in dotted decimal notation. In contrast to a network mask, the 0 bits in a wildcard mask represent ‘do care’ bits, while the 1 bits represent 'don’t care bits'. If the 'do care' bits in an IP address identical to the 'do care' bits in an IP address criterion, the IP address matches the criterion. All 'don’t care' bits are ignored. The 0s and 1s in a wildcard mask can be noncontiguous. For example, 0.255.0.255 is a valid wildcard mask.

Rule numbering

ACL rules can be manually numbered or automatically numbered. This section describes how automatic ACL rule numbering works.

Rule numbering step

If you do not assign an ID to the rule you are creating, the system automatically assigns it a rule ID. The rule numbering step sets the increment by which the system automatically numbers rules. For example, the default ACL rule numbering step is 5. If you do not assign IDs to rules you are creating, they are automatically numbered 0, 5, 10, 15, and so on. The wider the numbering step, the more rules you can insert between two rules.

By introducing a gap between rules rather than contiguously numbering rules, you have the flexibility of inserting rules in an ACL. This feature is important for a config-order ACL, where ACL rules are matched in ascending order of rule ID.

Automatic rule numbering and renumbering

The ID automatically assigned to an ACL rule takes the nearest higher multiple of the numbering step to the current highest rule ID, starting with 0.

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