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Table 1 Sorting ACL rules in depth-first order
ACL category
Sequence of tie breakers
IPv4 basic ACL
1.
VPN instance
2.
More 0s in the source IP address wildcard (more 0s means a narrower
IP address range)
3.
Rule configured earlier
IPv4 advanced ACL
1.
VPN instance
2.
Specific protocol number
3.
More 0s in the source IP address wildcard mask
4.
More 0s in the destination IP address wildcard
5.
Narrower TCP/UDP service port number range
6.
Rule configured earlier
IPv6 basic ACL
1.
VPN instance
2.
Longer prefix for the source IP address (a longer prefix means a
narrower IP address range)
3.
Rule configured earlier
IPv6 advanced ACL
1.
VPN instance
2.
Specific protocol number
3.
Longer prefix for the source IPv6 address
4.
Longer prefix for the destination IPv6 address
5.
Narrower TCP/UDP service port number range
6.
Rule configured earlier
Ethernet frame header ACL
1.
More 1s in the source MAC address mask (more 1s means a smaller
MAC address)
2.
More 1s in the destination MAC address mask
3.
Rule configured earlier
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, and the
1 bits represent "don’t care" bits. If the "do care" bits in an IP address are 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 comments and rule range remarks
Add a comment about an ACL rule to make it easy to understand. The rule comment appears below
the rule statement.
In addition, add a rule range remark to indicate the start or end of a range of rules created for the
same purpose.
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.