| Exam 400-101 | Question id=1078 | Layer 3 Technologies |
You issue the following commands on RouterA:
router bgp 100
neighbor 192.168.1.1 remote-as 100
neighbor 192.168.1.1 route-map map-in in
neighbor 192.168.1.1 route-map map-out out
neighbor 192.168.1.1 filter-list 1 in
neighbor 192.168.1.1 password gfhjkm
neighbor 192.168.1.2 remote-as 100
neighbor 192.168.1.2 route-map map-in in
neighbor 192.168.1.2 route-map map-out out
neighbor 192.168.1.2 filter-list 1 in
neighbor 192.168.1.2 password gfhjkm
neighbor 192.168.1.3 remote-as 100
neighbor 192.168.1.3 route-map map-in in
neighbor 192.168.1.3 route-map map-out out
neighbor 192.168.1.3 filter-list 1 in
neighbor 192.168.1.3 password gfhjkm
neighbor 192.168.1.4 remote-as 100
neighbor 192.168.1.4 route-map map-in in
neighbor 192.168.1.4 route-map map-out out
neighbor 192.168.1.4 filter-list 1 in
neighbor 192.168.1.4 password gfhjkm
neighbor 192.168.1.5 remote-as 100
neighbor 192.168.1.5 route-map map-extra in
neighbor 192.168.1.5 route-map map-out out
neighbor 192.168.1.5 route-map map-in in
neighbor 192.168.1.5 filter-list 1 in
neighbor 192.168.1.5 password gfhjkm
Which of the following statements are correct?
| A. |
RouterA uses eBGP to communicate with its neighbors. | |
| B. |
You can implement a peer group to simplify the configuration. | |
| C. |
Each neighbor is configured with a different number of route maps. | |
| D. |
Each neighbor is configured with the same number of AS path filters. |
You can implement a peer group to simplify and shorten the configuration. Additionally, each neighbor is configured with the same number of autonomous system (AS) path filters.
You can use a peer group to easily configure multiple neighbor statements that contain the same policy information for each neighbor. Using a peer group simplifies the configuration, reduces the chance for typographical errors, reduces the CPU and memory load on a router, and enables updates to be replicated more efficiently. To configure a peer group, you should issue the neighbor peer-group-name peer-group command in router configuration mode. To configure a peer group member, you should issue the neighbor ipaddress peergroup peergroupname command in router configuration mode.
The following commands configure a peer group named pg1 and effectively replace the commands previously issued in this scenario:
router bgp 100
neighbor pg1 peer-group
neighbor pg1 remote-as 100
neighbor pg1 route-map map-in in
neighbor pg1 route-map map-out out
neighbor pg1 filter-list 1 in
neighbor pg1 password gfhjkm
neighbor 192.168.1.1 peer-group pg1
neighbor 192.168.1.2 peer-group pg1
neighbor 192.168.1.3 peer-group pg1
neighbor 192.168.1.4 peer-group pg1
neighbor 192.168.1.5 peer-group pg1
neighbor 192.168.1.5 route-map map-extra in
Each neighbor is configured with one AS path filter. To create an AS path filter, you should issue the neighbor {ipaddress | peergroupname} filter-list access-list {in | out} command. The in keyword specifies an inbound path filter, and the out keyword specifies an outbound path filter.
Each neighbor is not configured with a different number of route maps. Each neighbor router is configured with an inbound route map named map-in and an outbound route map named mapo-ut. Although the neighbor router at 192.168.1.5 was configured with another inbound route map named map-extra, as indicated by the neighbor 192.168.1.5 route-map map-extra in command, it was replaced by the neighbor 192.168.1.5 route-map map-in in command. A router can be configured with only one inbound and one outbound route map per neighbor.
When converting the individual neighbor ipaddress route-map commands as a peer group configuration, you can specify each route map that is shared by all of them embers of the peer group in a single neighbor peergroupname route-map command. Any extra route maps that are used by only a few members of the peer group can be specified by using individual neighbor ipaddress route-map commands.
RouterA does not use external Border Gateway Protocol (eBGP) to communicate with its neighbors, because all of the routers share the same AS number, as indicated by the neighbor ipaddress remote-as 100 command. Routers that share the same AS number are internal BGP (iBGP) routers.