Question Of The Day: 26 March, 2008

Topic: Route Redistribution 

r1 is running EIGRP and RIP:

r1#sh ip proto sum
Index Process Name
0     connected
1     static
2     eigrp 100
3     rip

r1 has the following EIGRP routes:

r1#sh ip route eigrp
     2.0.0.0/32 is subnetted, 1 subnets
D       2.2.2.2 [90/2297856] via 10.1.12.2, 00:01:06, Serial1/0.12
     22.0.0.0/32 is subnetted, 1 subnets
D EX    22.2.2.2 [170/2560512256] via 10.1.12.2, 00:00:23, Serial1/0.12

r1’s network admin wants to redistribute the EIGRP routes and pass them on to r3 in the RIP domain (directly connected to r1).  Here is his configuration:

r1(config)#route-map EIGRP->RIP perm 10
r1(config-route-map)#match route-type external
r1(config-route-map)#set tag 1170
r1(config-route-map)#route-map EIGRP->RIP perm 20
r1(config-route-map)#set tag 190
r1(config-route-map)#router rip
r1(config-router)#redistribute eigrp 100 route-map EIGRP->RIP

Which EIGRP routes will appear in r3’s (RIP) routing table?

Click here for the answer.

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Yesterday’s Question

 Question Of The Day: 25 March, 2008 

Topic: EIGRP

Which of the following commands will make EIGRP AS 100 consider delay only when calculating the EIGRP metric?

1) router eigrp 100
    default metric 1 1 0 1 1500

2) router eigrp 100
    metric weights 0 1 0 0 0 0    

3) router eigrp 100
    metric weights 0 0 1 0 0 0

4) router eigrp 100
    metric weights 0 0 0 1 0 0

Answer:

4) router eigrp 100
    metric weights 0 0 0 1 0 0

metric weights (EIGRP)

metric weights tos k1 k2 k3 k4 k5

The first value is ‘tos’ (Type of Service) and is always zero.  The remaining five values are the EIGRP ‘k-values’.

If k5 equals 0, the composite EIGRP metric is computed according to the following formula:

metric = [k1 * bandwidth + (k2 * bandwidth)/(256 - load) + k3 * delay]

If k5 does not equal zero, an additional operation is performed:

metric = metric * [k5/(reliability + k4)]

The ‘trick’ is not assuming that the five k-values match up with the five EIGRP metrics:

default-metric (EIGRP)

default-metric bandwidth delay reliability loading mtu

The five EIGRP metrics (which I memorized with the mnemonic “Big Dogs Really Love Meat”) do NOT correspond to the k-values.  So don’t do what I did and use ‘metric weights 0 0 1 0 0 0′