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Are these 'ip route' clean and correct ?

PC-A IP=10.1.1.1 +--+[e0/0:10.1.1.5 RouterA s0/0:195.1.1.4]===V35===[s0:195.1.1.10 RouterB 152.1.1.1:e0]+--+[e0:RouterC 152.1.1.2]

(Please see attachment for a better diagram)

From any device on the network, I can ping each other OK.

However, my question is, in order to accomplish this I put two 'ip route' entries on RouterA and two entries on RouterC. I just would like to confirm that what I did is correct and clean ? I mean, do you see a way that I could solve this with less 'ip route' entries ?(assume I don't want to use dynamic routing).

RouterA

ip route 10.1.1.0 255.255.255.0 Ethernet0/0

ip route 152.1.1.0 255.255.255.0 195.1.1.10

RouterB

ip route 10.1.1.0 255.255.255.0 195.1.1.4

RouterC

ip route 10.1.1.0 255.255.255.0 152.1.1.1

ip route 195.1.1.0 255.255.255.0 152.1.1.1

3 REPLIES

Re: Are these 'ip route' clean and correct ?

Hi,

this is nearly the way to do it. Every router needs an entry in the IP routing table for every network you would like to have connectivity to. As the directly attached networks are already in the IP routing table, there is no need for a static route in this case. The only way of further reducing the number of entries is summarizition. So this should also work:

RouterA

ip route 152.1.1.0 255.255.255.0 195.1.1.10

RouterB

ip route 10.1.1.0 255.255.255.0 195.1.1.4

RouterC

ip route 10.1.1.0 255.255.255.0 152.1.1.1

ip route 195.1.1.0 255.255.255.0 152.1.1.1

OR

RouterC

ip route 0.0.0.0 0.0.0.0 152.1.1.1

!Summarization

Hope this helps! Please rate all posts.

Regards, Martin

Re: Are these 'ip route' clean and correct ?

Hello,

in addition to Martin's post, I am thinking that all three routers C just need a default route. My reasoning is (assuming that all IP addresses are class C/24 addresses):

RouterA knows about:

10.1.1.0

195.1.1.0

Router B knows about:

195.1.1.0

152.1.1.0

RouterC knows about:

152.1.1.0

Now, if router A would need to send traffic to 152.1.1.0, the default route would send it to router B, and router B already knows about 152.1.1.0 because it is directly connected.

If router C would need to send traffic to router A, it would use the default route to router B, and router B would use the default route to router A.

If router B would need to send traffic to 10.1.1.0, it would use the default route to router A as well.

So, putting this all together, the following should work as well:

RouterA

ip route 0.0.0.0 0.0.0.0 Serial0/0

RouterB

ip route 0.0.0.0 0.0.0.0 Serial0

RouterC

ip route 0.0.0.0 0.0.0.0 Ethernet0

My apologies if I am off here, but give it a try...

Regards,

GNT

Re: Are these 'ip route' clean and correct ?

Careful,

this will introduce routing loops for any nonexistent destination address. Thus I used the other approach.

Regards, Martin

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