Controlling Granularity Of Routing Information - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - IP-IPV6-IGP CONFIGURATION GUIDE 2010-10-31 Configuration Manual

JunosE 11.3.x IP, IPv6, and IGP Configuration Guide
redistribute isis ip

Controlling Granularity of Routing Information

distribute-domain-wide
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Use to redistribute IS-IS IPv6 routes from level 1 to level 2 or from level 2 to level 1.
Use the route-map keyword to specify the route map to be applied. You can use the
route map to set a route tag for redistributed routes.
Example
host1(config-router-af)#redistribute isis level-1 into level-2
Use the no version to stop redistribution of IPv6 routes between the specified levels.
See redistribute isis
Use to redistribute IS-IS IP routes from level 1 to level 2 or from level 2 to level 1.
Specify one of the following:
Use the distribute-list keyword to specify the IP access list used to filter routes
between levels. Issue the access list command to create a route filter to apply to
the redistribution.
Use the route-map keyword to specify the route map to be applied. You can use the
route map to set a route tag for redistributed routes.
Example 1—Redistributes IS-IS IP routes between levels, filtered by an access list.
host1(config-router)#redistribute isis ip level-1 into level-2 distribute-list leakList
Example 2—Redistributes IS-IS IP routes between levels, filtered by a route map.
host1(config-router)#redistribute isis ip level-2 into level-1 route-map boston01
Use the no version to stop redistribution of IP routes between the specified levels.
See redistribute isis ip
You can force the distribution of level 2 routing information to level 1 routers in other
areas to improve the quality of the resulting routes, but at the cost of reduced scalability.
Use to increase the granularity of routing information within a domain.
Domainwide prefix distribution enables a routing domain running with both level 1 and
level 2 IS-IS routers to distribute IP prefixes from level 2 to level 1 between areas.
The major advantage for using domainwide prefix distribution is to improve the quality
of the resulting routes within a domain by distributing more specific information.
The major disadvantage of using domainwide prefix distribution is that it affects the
scalability of IS-IS. When used, it increases the number of prefixes throughout the
domain, causing increased memory consumption, transmission requirements, and
computation requirements throughout the domain.
A trade-off decision must be made between scalability and optimality.
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