Route filtering using distribute lists provides control over the routes RIP receives and advertises. This control may be exercised
globally or per interface.
Filtering is controlled by distribute lists. Input distribute lists control route reception, and input filtering is applied
to advertisements received from neighbors. Only those routes that pass input filtering will be inserted in the RIP local routing
table and become candidates for insertion into the IPv6 routing table.
Output distribute lists control route advertisement; Output filtering is applied to route advertisements sent to neighbors.
Only those routes passing output filtering will be advertised.
Global distribute lists (which are distribute lists that do not apply to a specified interface) apply to all interfaces. If
a distribute list specifies an interface, then that distribute list applies only to that interface.
An interface distribute list always takes precedence. For example, for a route received at an interface, with the interface
filter set to deny, and the global filter set to permit, the route is blocked, the interface filter is passed, the global
filter is blocked, and the route is passed.
IPv6 prefix lists are used to specify certain prefixes or a range of prefixes that must be matched before a permit or deny
statement can be applied. Two operand keywords can be used to designate a range of prefix lengths to be matched. A prefix
length of less than, or equal to, a value is configured with the le keyword. A prefix length greater than, or equal to, a value is specified using the ge keyword. The ge and le keywords can be used to specify the range of the prefix length to be matched in more detail than the usual ipv6-prefix / prefix-length argument. For a candidate prefix to match against a prefix list entry three conditions can exist:
The candidate prefix must match the specified prefix list and prefix length entry.
The value of the optional le keyword specifies the range of allowed prefix lengths from the prefix-length argument up to, and including, the value of the le keyword.
The value of the optional ge keyword specifies the range of allowed prefix lengths from the value of the ge keyword up to, and including, 128.
Note that the first condition must match before the other conditions take effect.
An exact match is assumed when the ge or le keywords are not specified. If only one keyword operand is specified then the condition for that keyword is applied, and
the other condition is not applied. The prefix-length value must be less than the ge value. The ge value must be less than, or equal to, the le value. The le value must be less than or equal to 128.