Very Confusing Situation

[glen.krinsky]

Greetings all, I am by no means an expert in switching and routing, but I know my fair share.  I recently ran into an interesting situation in my lab.  I have a network with a single switch connected to a core switch, which is then connected to a router, then another router and another switch.  See the attached file...I may have lost you...lol. 

So, in my network example attached, client 1, with an IP address of 192.168.70.30 and a subnet mask of 255.255.255.128 cannot ping 172.16.100.34.  If I change the subnet mask to 255.255.255.0 it can.  Ok, here is the rub...Client 2 and 4 have a subnet mask of 255.255.255.128 and CAN ping 172.16.100.34.  Clients 1 and 3 have to be set to 255.255.255.0.  These are all on the same network, VLAN, switch, ect.  FOr the life of me I cannot see a difference in any of the switch or router configurations OR the clients themselves.

Any Ideas???

[siddhartham]

Thts weired, can you do a traceroute from the clients to 172.16.100.34 and post the outputs.

[glen.grant]

  Don't know unless the client mask or default gateways are incorrect on the  ones that do not work .  On the ones that do not work trace and see where it stops .  How is the routing setup?  Dynamic , static etc..  Check that these look ok and the masking in any statics are corrrect.

[ebarticel]

Are the clients running the same OS? Does the core switch do any routing?