Refer to the exhibit.
All switch interfaces shown in the exhibit have these characteristics:
Are configured in routed-mode
Have IP addresses
Run Open Shortest Path First (OSPF)
Network architect wants to ensure that routing switch 1 uses the faster link in preference to the
slower link, which should be used in failover situations. Which step should be architect perform to
meet this requirement?
A.
Disable ECMP on Routing switch 1 and on other routing switches for consistency.
B.
Set the designated router preference on Routing switch 2 interface Forty1/0/48 to a lower level
than on Routing switch 3 interface Ten1/0/1:1.
C.
Set the OSPR reference bandwidth on the routing switches to an appropriate level, such as
100000 Mbps.
D.
Configure Routing switch 1 interface Ten1/0/1:1 as a silent, or a passive, OSPF interface.
Explanation:
Changing the switch interface to silent/passive OSPF would make it so routing switch 1 doesn’t know about routing switch 3. It wouldn’t fail over to the slower link… because it doesn’t know about it.
Quote from Cisco:
“For OSPF, a passive interface does not send or process received Hellos. This prevents routers from becoming neighbors on that interface.”
The Study Guide says the following:
You should also make sure that the most favorable routes are selected. Bandwidth on a link acts as the default cost for a link. Generally, ask network administrators to set the reference bandwidth to the highest bandwidth available on OSPF links. Better yet, have the administrators prepare for the future by setting the reference bandwidth to a higher bandwidth still. For example, you might use 100G as the reference bandwidth in anticipation that your network will soon support that speed.”
100G = 100,000 Mbps, so I’m pretty sure that C is the answer.
B looks okay too, but setting the cost to a static number might inhibit future growth. C looks best to me.
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C is correct
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only C.
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