Administative Distance and Static Route

duahimanshu816 · ‎02-07-2018

Hello,

I am facing some issue in Routing, kindly help me figure it out. thanks in advance.

I have multiple routes into my cisco 2900 series router i.e.

0.0.0.0 0.0.0.0 192.168.200.1 (towards my firewall for accessing internet)

192.168.15.0/24 192.168.17.1

192.168.18.0/24 192.168.19.1

192.168.21.0/24 192.168.22.1

the issue is some time the links fluctuates(not all together) and then comes back again.

today when there was issue and one link was down i was troubleshooting i found something strange.

when i ping 192.168.15.0 network reply comes as follows:-

reply from 192.168.103.1 ttl is exceeded.

192.168.103.1 is not in our network at all. when i did a traceroute i found that that goes out through 192.168.200.1 (towards firewall) and then Port B on firewall which public ip (ISP) interface out.

I ping 192.168.103.1 through firewall PORT B it pings that seems the issue from ISP.

Now my first question is how 192.168.15.0 network can pass through my firewall interface(192.168.200.1) as it's next hope is 192.168.17.1 ??

Second question :- In routing table which route will be prefrable ? I have one Default route and rest others?

chrihussey · ‎02-07-2018

Now my first question is how 192.168.15.0 network can pass through my firewall interface(192.168.200.1) as it's next hope is 192.168.17.1 ?

ANS - You said a link was down when this happened, Was it the link to 192.168.17.1? If so, then that static should be withdrawn as the next hop is now invalid and then the default route would take over.

In routing table which route will be prefrable ? I have one Default route and rest others?

ANS - As a general rule, all things being equal, the more specific route should take precedence. So if all links are up and all routes are valid, then any matches to the static routes should work, anything else would follow the default route.

Hope this makes sense and helps.

mhrznamn · ‎02-07-2018

Hi,

The first thing to verify is , do you have route to 192.168.17.1 in your routing table.

If there is no valid route to 192.168.17.1 ,192.168.15.0/24 takes default route and tries to enter isp network.

As there is reply from 192.168.103.1 ,this is the ISP's problem that it is allowing private network from its client.

duahimanshu816 · ‎02-23-2018

Thank your very much for your time, i got my ans.