Alcatel-Lucent 7750 SR-OS, Configuration Manual

Page: 413 / 674

Filter Policies
7750 SR OS Router Configuration Guide Page 413
Match-list for Filter Policies
Figure 15 depicts an approach to implement logical OR on a list of matching criterion (IPv4
address prefixes in this example) in one or more filter policies prior to introduction of match list.
Figure 15: IOM/CPM Filter Policy using Individual Address Prefixes
An operator has to create one entry for each address prefix to execute a common action. Each entry
defines a match on a unique address prefix from the list plus any other additional match criteria
and the common action. If the same set of address prefixes needs to be used in another IOM or
CPM filter policy, an operator again needs to create one entry for each address prefix of the list in
those filter policies. Same procedure applies (not shown above) if another action needs to be
performed on the list of the addresses within the same filter policy (when for example specifying
different additional match criteria). This process can introduce large operational overhead,
especially when a list contains many elements or/and needs to be reused multiple times across one
or more filter policies.
Match list for CPM and IOM filter policies are introduced to eliminate above operational
complexity by simplifying the IOM and CPM filter policy management on a list of a match
criterion. Instead of defining multiple filter entries in any given filter, an operator can now group
same type of the matching criteria into a single filter match list, and then use that list as a match
criterion value, thus requiring only single filter policy entry per each unique action. The same
match list can be used in one or more IOM filter policies as well as CPM filter policies.
The match lists further simplify management and deployment of the policy changes. A change in a
match-list content is automatically propagated across all policies employing that list in their match
criteria, thus only a single configuration change is required to trigger policy changes when a list is
used by multiple entries in one or more filter policies.
Figure 16 depicts how the IOM/CPM filter policy illustrated at the top of this section changes with
a filter match list usage (using IPv4 address prefix list in this example).
Entry K+1
+1: match IPv4 Prefix 1
Entry K+2
: match IPv4 Prefix 2
Entry K+N
match IPv4 Prefix N
CPM Filter
IOM Filters
OSSG729
Entry M+1
match IPv4 Prefix 1
Entry M+2
match IPv4 Prefix 2
Entry M+N
match IPv4 Prefix N
IPv4 Prefix 1
IPv4 Prefix 2
IPv4 Prefix N