08-27-2013 01:44 AM - edited 03-07-2019 03:08 PM
Hi
I`m suddenly having problems with some static routes on a WS-C3750G-12S-E running 12.2(44)SE5.
The routing table is really simple, only some static routes and a couple of VRFs.
Gateway of last resort is 10.0.224.29 to network 0.0.0.0
10.0.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 10.0.232.0/25 is directly connected, Vlan1801
C 10.0.224.28/30 is directly connected, Vlan1208
S* 0.0.0.0/0 [1/0] via 10.0.224.29
I have several 3750`s running very similar setup in the same network without problems.
And this one was working fine till a couple of days ago.
Now clients with addresses in the 10.0.232.0/25 network are routed back to them selves if trying to reach an address in the 10.0.0.0/16 range.
That is, if a client with IP 10.0.232.50 tries to reach 10.0.230.50 it loops back to it self.
Traceroute shows the 3750 with ip 10.0.232.1 looping it back.
If it tries to reach 10.0.230.1 or an IP that is not in use in the 10.0.232.0/25 it routes just fine, and traceroute is fine.
For example 10.0.232.43 is not in use, and traceroute from 10.0.232.50 to 10.0.230.43 works just fine.
IP 10.0.232.44 is in use, and traceroute from 10.0.232.50 to 10.0.230.44 loops back to 10.0.232.44.
Traceroute to 10.0.230.50 looks like this.
1 10.0.232.1
2 10.0.232.50
3 10.0.232.1
4 10.0.232.50
5 10.0.232.1
6 10.0.232.50 ...
If traceroute or ping is run from the 3750s CLI all is fine, only occurs when running from clients.
This has been working for a long time, no config changes made.
Other 3750`s with similar config (same type of subnetting/static routes) work just fine.
Hope somebody knows what might cause this, will really appreciate it.
Regards
08-29-2013 12:12 AM
I`m in a pinch here, anybody got thoughts on this?
08-29-2013 12:20 AM
It is really strange behaviour. A couple of thoughts:
Kevin Dorrell
Luxembourg
08-29-2013 02:00 AM
Thank you Kevin for reply.
I can not find anything special with the clients.
At one time a was in doubt if there was a customer with a misconfigured device.
So at night time I blocked access to the clients, and tried with a client I configured, same results.
No NAT on my side, clients have firewalls and use NAT.
Tried a reload at night, unfortunately it did not help.
08-29-2013 03:11 AM
Dear perpaal,
Post the configs or confirm if there is some traffic redirection ??
Is the next hope 10.0.224.29 reachable from both the subnets?
Is this behavior with a single subnet ?
You can try to connect a single host to the a particular vlan and test, instead of entire series of devices (to confirm if something is weird on other side.)
08-29-2013 04:00 AM
Hi Parvesh
Yes, 10.0.224.29 is reachable for both subnets.
The problem is just on this one subnet, the others seem to be normal.
system mtu routing 1500
vtp mode transparent
ip routing
spanning-tree mode pvst
spanning-tree extend system-id
interface Vlan208
ip address 10.0.224.30 255.255.255.252
interface Vlan801
ip address 10.0.232.1 255.255.255.128
ip classless
ip route 0.0.0.0 0.0.0.0 10.0.224.29
system mtu routing 1500
vtp mode transparent
ip routing
spanning-tree mode pvst
spanning-tree extend system-id
interface Vlan1207
ip address 10.0.224.25 255.255.255.252
interface Vlan1208
ip address 10.0.224.29 255.255.255.252
interface Vlan1209
ip address 10.0.224.33 255.255.255.252
interface Vlan1210
ip address 10.0.224.37 255.255.255.252
interface Vlan1211
ip address 10.0.224.41 255.255.255.252
ip route 10.0.224.0 255.255.255.252 10.0.224.2
ip route 10.0.225.0 255.255.255.0 10.0.224.2
ip route 10.0.225.0 255.255.255.0 10.0.224.34
ip route 10.0.226.0 255.255.255.128 10.0.224.38
ip route 10.0.227.0 255.255.255.0 10.0.224.34
ip route 10.0.228.0 255.255.255.0 10.0.224.26
ip route 10.0.229.0 255.255.255.0 10.0.224.34
ip route 10.0.230.0 255.255.255.0 10.0.224.34
ip route 10.0.232.0 255.255.255.0 10.0.224.30
ip route 10.0.233.0 255.255.255.0 10.0.224.42
08-29-2013 11:23 PM
Can you share the logs, debug ip packet ?
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