Administrative groups (admin groups), also known as affinity, are used to tag IP interfaces which share a specific characteristic with the same identifier. For example, an admin group identifier could represent all links which connect to core routers, or all links which have bandwidth higher than 10G, or all links which are dedicated to a specific service.
The user first configures locally on each router the name and identifier of each admin group.
CLI syntax
config>router>if>if-attribute>admin-group group-name value group-valueA maximum of 32 admin groups can be configured per system.
Next the user configures the admin group membership of the IP interfaces used in LFA. The user can apply admin groups to IES, VPRN, or network IP interface.
CLI syntax
config>router>interface>if-attribute>admin-group group-name [group-name...(up to 5 max)]
config>service>ies>if>if-attribute>admin-group group-name [group-name...(up to 5 max)]
config>service>vprn >if>if-attribute>admin-group group-name [group-name...(up to 5 max)]The user can add as many admin groups as configured to a specified IP interface. The same above command can be applied multiple times.
The no form of the admin-group command under the interface deletes one or more of the admin-group memberships of the interface. It deletes all memberships if no group name is specified.
Finally, the user adds the admin group constraint into the route next hop policy template.
CLI syntax
configure router route-next-hop-template template template-name
include-group group-name [pref 1]
include-group group-name [pref 2]
exclude-group group-nameEach group is entered individually. The include-group statement instructs the LFA SPF selection algorithm to pick up a subset of LFA next hops among the links which belong to one or more of the specified admin groups. A link which does not belong to at least one of the admin-groups is excluded. However, a link can still be selected if it belongs to one of the groups in a include-group statement but also belongs to other groups which are not part of any include-group statement in the route next hop policy.
The pref option is used to provide a relative preference for the admin group to select. A lower preference value means that LFA SPF first attempts to select a LFA backup next hop which is a member of the corresponding admin group. If none is found, then the admin group with the next higher preference value is evaluated. If no preference is configured for a specified admin group name, then it is supposed to be the least preferred (for example, numerically the highest preference value).
When evaluating multiple include-group statements within the same preference, any link which belongs to one or more of the included admin groups can be selected as an LFA next hop. There is no relative preference based on how many of those included admin groups the link is a member of.
The exclude-group statement simply prunes all links belonging to the specified admin group before making the LFA backup next hop selection for a prefix.
If the same group name is part of both include and exclude statements, the exclude statement wins. It other words, the exclude statement can be viewed as having an implicit preference value of 0.