Your network consists of a large hub-and-spoke Frame Relay network with a CIR of 56 kb/s for
each spoke. Which statement about the selection of a dynamic protocol is true?
A.
EIGRP would be appropriate if LMI type ANSI is NOT used.
B.
EIGRP would be appropriate, because the Frame Relay spokes could be segmented into their
own areas.
C.
EIGRP would be appropriate, because by default, queries are not propagated across the slow
speed Frame Relay links.
D.
EIGRP would be appropriate, because you can manage how much bandwidth is consumed
over the Frame Relay interface.
Explanation:
By default, EIGRP will limit itself to using no more than 50% of the interface bandwidth. The
primary benefit of controlling EIGRP’s bandwidth usage is to avoid losing EIGRP packets, which
could occur when EIGRP generates data faster than the interface line can absorb it. This is of
particular benefit on Frame Relay networks, where the access interface bandwidth and the PVC
capacity may be very different.
For example, in our Frame Relay topology a Hub is connected with 4 Spoke routers. The main
Frame Relay interface on Hub router is 512Kpbs which is not enough to use for 6 links of 128
Kbps ( = 768 Kbps).The solution here is we can use 512 / 6 = 85 Kbps on each subinterface of Hub by using
“bandwidth 85 command. For example:
Hub(config)#interface Serial0/0.1 point-to-pointHub(config-subif)#bandwidth 85
Also on Spoke routers we need to set this value. For example on Spoke1:
Spoke1(config)#interface Serial0/1.0 point-to-pointSpoke1(config-subif)#bandwidth 85
Notice that by default, EIGRP limits itself to use no more than 50% of the configured interface
bandwidth. In this case EIGRP will not use more than 42.5 Kbps (50% of 85 Kbps).
(For more information about implementing EIGRP over Frame Relay, please read
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094063.shtml)
