3Com Switch 4800G 24-Port Configuration Manual page 839

IPv6 ACL Naming
n
IPv6 ACL Match Order
When creating an IPv6 ACL, you can specify a unique name for it. Afterwards, you
can identify the IPv6 ACL by its name.
An IPv6 ACL can have only one name. Whether to specify a name for an ACL is up
to you. After creating an ACL, you cannot specify a name for it, nor can you
change or remove the name of the ACL.
The name of an IPv6 ACL must be unique among IPv6 ACLs. However, an IPv6 ACL
and an IPv4 ACL can share the same name.
Similar to IPv4 ACLs, IPv6 ACLs are sequential collections of rules defined with
different matching parameters. The order in which a packet is matched against the
rules in an IPv6 ACL may affect how the packet is handled.
Like in IPv4 ACLs, the following two match orders are available in IPv6 ACLs:
config: where rules are compared against in the order in which they are
■
configured.
auto: where depth-first match is performed.
■
Depth-first match for a basic IPv6 ACL
The following shows how your switch performs depth-first match in a basic IPv6
ACL:
1 Sort rules by source IPv6 address wildcard first and compare packets against the
rule configured with a longer prefix in the source IPv6 address wildcard prior to
other rules.
2 If two rules are present with the same prefix length in their source IPv6 address
wildcards, compare packets against the rule configured first prior to the other.
Depth-first match for an advanced IPv6 ACL
The following shows how your switch performs depth-first match in an advanced
IPv6 ACL:
1 Sort rules by protocol range first, and compare packets against the rule with the
protocol carried on IPv6 specified prior to other rules.
2 If two rules are present with the same protocol range, look at source IPv6 address
wildcard in addition. Then, compare packets against the rule configured with a
larger prefix length in the source IPv6 address wildcard prior to the other.
3 If the prefix lengths in the source IPv6 address wildcards are the same, look at the
destination IPv6 address wildcards. Then, compare packets against the rule
configured with a larger prefix length in the destination IPv6 address wildcard prior
to the other.
4 If the prefix lengths in the destination IPv6 address wildcards are the same, look at
the Layer 4 port number (TCP/UDP port number). Then compare packets against
the rule configured with the lower port number prior to the other.
5 If the port numbers are the same, compare packets against the rule configured
first prior to the other.
The comparison of a packet against an ACL stops once a match is found. The
packet is then processed as per the rule.
Introduction to IPv6 ACL 839