Redistribute EIGRP to OSPF - Which interface to use

[Adrian_T]

I am currently studying CCNP Route and doing some labs here in Digitaltut website. 

Kindly enlighten me which interface should I choose to be the reference for the redistribution for R3

f0/0 or f1/0?

I tried to use the parameters of f1/0 and I can still ping the loopback, I wonder why did they use f0/0 as a reference? 

 

redistribute ospf 1 metric 100000 100 255 1 1500
Type escape sequence to abort.
Tracing the route to 172.16.100.1

1 192.168.1.2 4 msec 4 msec 0 msec
2 192.168.2.3 8 msec 20 msec 24 msec
3 192.168.4.4 40 msec 20 msec 36 msec

redistribute ospf 1 metric 100000 10 255 1 1500
Tracing the route to 172.16.100.1

1 192.168.1.2 0 msec 0 msec 0 msec
2 192.168.2.3 8 msec 24 msec 24 msec
3 192.168.4.4 36 msec 48 msec 36 msec

Here is the whole lab setup

http://www.digitaltut.com/ospf-eigrp-redistribute-lab

[Meheretab Mengistu]

Hi Adrian,

Kindly enlighten me which interface should I choose to be the reference for the redistribution for R3

f0/0 or f1/0?

Generally when you redistribute between different protocols you will define your metrics. For example, when you redistribute from OSPF to EIGRP, you need to select values for Bandwidth, Delay, Load, Reliability, MTU as EIGRP calculates cost based on composite metric.. In your setup, they select "redistribute ospf 1 metric 10000 100 255 1 1500". The default K values for EIGRP are 1 0 1 0 0; so the deciding values are Bandwidth and Delay.

In the real world, you need to carefully consider the K values as they could impact the route it takes.

HTH,

Meheretab

[Georg Pauwen]

Hello,

I am unclear on what you are asking. Which parameters are you referring to ?

[Adrian_T]

Sorry for the confusion, I mean for the R3 configuration, they use the interface fa0/0 for redistribution. 

I tried to use the interface of fa1/0 parameters and still able to reach the loopback.

why did they use the interface of R3 fa0/0?

Lab set up

http://www.digitaltut.com/route-eigrp-ospf-redistribution-sim

[Meheretab Mengistu]

They do not specifically use fa0/0 parameters. They assigned those specific values to calculate the cost (using composite metric). The default values are K1=1, K3=1 and K2,K4,K5=0; which makes the cost calculation to be dependent on bandwidth and delay only.

One thing to remember is that whether you use the above values or different parameters (associated with fa0/1), you will be able to reach the loopback address from R1 as far as redistribution from OSPF is successful. The path it takes could be different though (depending on the cost and the alternate routes).

HTH,
Meheretab