Last Updated on August 7, 2021 by Admin 3
You administer the BGP network in the following exhibit:
Between which routers can the cost community attribute be passed? (Select the best answer.)
- between all of the routers in this scenario
- between none of the routers in this scenario
- only between RouterA and RouterB
- only between RouterA and RouterC
Explanation:
The Border Gateway Protocol (BGP) cost community attribute can be passed only between RouterA and RouterB. The cost community, which is a nontransitive extended community, is passed only between internal BGP (iBGP) and confederation peers? it is not sent to external BGP (eBGP) peers. When multiple equalcost paths exist, the path with the lowest cost community number is preferred.
To configure the cost community attribute in a route map, you should issue the set extcommunity costcommunityidcostvalue command from routemap configuration mode. The community ID, which is defined by the communityid variable, is a value from 0 through 255. The cost, which is defined by the costvalue variable, is a value from 0 through 4294967295, with a default value of half of the maximum, or 2147483647. If two paths have the same cost, the path with the lowest community ID will be preferred.
When aggregate routes or multipaths are used and several component routes use the same community ID, the highest cost is applied to the aggregate or multipath route. If one or more of the component routes do not carry the cost community attribute or are configured with different community IDs, the default value of 2147483647 is applied to the aggregate or multipath route.
The Border Gateway Protocol (BGP) cost community attribute can be passed only between RouterA and RouterB. The cost community, which is a nontransitive extended community, is passed only between internal BGP (iBGP) and confederation peers? it is not sent to external BGP (eBGP) peers. When multiple equalcost paths exist, the path with the lowest cost community number is preferred.
To configure the cost community attribute in a route map, you should issue the set extcommunity costcommunityidcostvalue command from routemap configuration mode. The community ID, which is defined by the communityid variable, is a value from 0 through 255. The cost, which is defined by the costvalue variable, is a value from 0 through 4294967295, with a default value of half of the maximum, or 2147483647. If two paths have the same cost, the path with the lowest community ID will be preferred.
When aggregate routes or multipaths are used and several component routes use the same community ID, the highest cost is applied to the aggregate or multipath route. If one or more of the component routes do not carry the cost community attribute or are configured with different community IDs, the default value of 2147483647 is applied to the aggregate or multipath route.
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