Alcatel-Lucent 7750 SR-OS, Руководство по настройке

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Router Interface Commands
Page 178 7750 SR OS Router Configuration Guide
A policy template can be used in both IS-IS and OSPF to apply the specific criteria to prefixes
protected by LFA. Each instance of IS-IS or OSPF can apply the same policy template to one or more
interface.
The commands within the route next-hop policy template use the begin-commit-abort model. The
following are the steps to create and modify the template:
1. To create a template, the user enters the name of the new template directly under the route-next-
hop-policy context.
2. To delete a template that is not in use, the user enters the no form for the template name under
the route-next-hop-policy context.
3. The user enters the editing mode by executing the begin command under the route-next-hop-
policy context. The user can then edit and change any number of route next-hop policy tem-
plates. However, the parameter value will still be stored temporarily in the template module
until the commit is executed under the route-next-hop-policy context. Any temporary parame-
ter changes will be lost if the user enters the abort command before the commit command.
4. The user is allowed to create or delete a template instantly once in the editing mode without the
need to enter the commit command. Furthermore, the abort command, if entered, will have no
effect on the prior deletion or creation of a template.
Once the commit command is issued, IS-IS or OSPF will re-evaluate the templates and if there are
any net changes, it will schedule a new LFA SPF to re-compute the LFA next-hop for the prefixes
associated with these templates.
Parameters template-name — Specifies the name of the template, up to 32 characters.
include-group
Syntax include-group group-name [ pref pref ]
no include-group group-name
Context config>router>route-next-hop-policy>template
Description This command configures the admin group constraint into the route next-hop policy template.
Each 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 will first attempt 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 given admin group name,
then it is supposed to be the least preferred, i.e., 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.