I have the setup shown in the attached drawing , I dont know why SWITCH_A is not using the default route .
when I try to ping any subnet behind SWITCH_B , SWITCH_A cannot reach it if I didnot specifically add a static route to that subnet pointing to switch_B
ip route 10.12.217.0 255.255.255.0 10.12.223.253 !!!
SWITCH_A routing table is:
Gateway of last resort is 10.12.223.254 to network 0.0.0.0
10.0.0.0/8 is variably subnetted, 31 subnets, 4 masks
C 10.12.223.252/30 is directly connected, GigabitEthernet3/6
C 10.12.220.0/24 is directly connected, Vlan220
C 10.12.218.0/24 is directly connected, Vlan218
C 10.12.216.0/24 is directly connected, Vlan216
C 10.12.217.0/24 is directly connected, Vlan217
S* 0.0.0.0/0 [1/0] via 10.12.223.254
Can anyone explain this behavior !!!
Solved! Go to Solution.
Is it just the 10.12.x.x subnets behind B you have tried to ping. If it is altho very unlikely can you make sure you don't have
"no ip classless" in your config on Switch A.
In the text you stated, your next hop for the static 10.12.217.0/24 is 10.12.223._253_
In the routing table output, your static default's next hop is 10.12.223._254_
You have a VLAN (217) that's a directly connected route. It's going to try to go out that interface before it'll try to leave the switch. That's why it's working if you add the static route.
Are you using a routing protocol like bgp, ospf, or rip?
Is it possible that the addresses configured on the switches are not the same as shown in the drawing. In you example of the static route that works the nest hop is .253, which according to the drawing should be the local interface. If the route with .253 works but the route with .254 does not work then it suggests that perhaps .254 is really the local address and .253 is really the other switch address.
An easy way to demonstrate this would be to post the output of show ip interface brief.
Sorry ,I did a mistake when I paste the configuration.actually I wrote them , I didnot capture them from the switches to minimize the post.
the route on SWITCH_A is:
ip route 0.0.0.0 0.0.0.0 10.12.223.253 (not 254)
and subnet 217 is not directly connected to switch A , please ignore the above output.
I'm sure I dont have basic error, it is exactly as I explained.
no ip classless command is configured.
Yes, I do have EIGRP behind SWITCH_A and the subnet 10.12.218.0 10.12.216.0 is advertised there.But there is no EIGRP between SWITCH_A, and SWITCH_B
"no ip classless command is configured"
Sorry but could you be more specific as that could be taken 2 different ways. Are you saying that in your config there is not a line with
"no ip classless"
What IOS version are you running ?
Well, I would do as Rick suggested by doing a sh ip int brief.
If you can post the sections from sh run:
ip route (all lines)
router eigrp AS (all config)
interface (whatever your OUTBOUND interface is) config
And the ACTUAL routing table would be nice :-)
please see attached notepad
please dont worry about .253 or .254 order , regardless SWITCH_A has .254 or .253 , the idea should be clear :)
.254 is on SIWTCH_B .253 is on SWITCH_A
ip route 10.12.217.0 255.255.255.0 10.12.223.254
ip route 184.108.40.206 255.255.0.0 10.12.223.254
are added to the configuration otherwise the subnets 10.12.217.0 and 220.127.116.11 will not be reachable.
Can you post your eigrp configuration from the other switch and the static routes from it?
You have this in your routing table
D 10.12.216.0/21 is a summary, 7w0d, Null0
which is because of this entry under your eigrp config
network 10.12.216.0 0.0.7.255
Problem is 10.12.217.0/24 is on the other switch. But the default route will not be used because you have a more specific route ie.
D 10.12.216.0/21 is a summary, 7w0d, Null0
so traffic is blackholed. Only when you add in a specific entry for 10.12.217.0/24 does that get used.
You need to break down your advertisements under your router eigrp config.
Well that depends. If you have the same config on switch B in terms of summarising 10.12.216.0/21 then traffic will actually be sent across the link but again Switch B would drop it when it tried to send it back.
This is assuming when you ping the source IP is from 10.231.216.0/21 summary range.
An easier solution for you would just be to run EIGRP between your switches - is there some reason you are not ?
Actually , we cannot run eigrp between them , because SWITCH_A and SWITCH_B are in different parts of teh network , they should not share the routing table (IT department policy)
anyway , SWITCH_B has no dynamic routing configured , 18.104.22.168 is simply a vlan on SWITCH_B that need to be reached from SWITCH_A.
You'll need to add a route for every network that's on switch A to switch B if you're not using eigrp between them for A to see the return traffic back.
So whatever VLANs you need to get to on switch A from B, you'll need a static route for on the B switch.