06-11-2007 07:28 AM - edited 03-05-2019 04:37 PM
We are bringing up a new non-trunking core. Our current core has a 10.0.0.0/16 network management VLAN. The new core has a 10.0.20.0/24 network management VLAN. With the current setup I am unable to reach the /24 from the /16 VLAN. I believe this is due to the fact that EIGRP sees the /24 belonging to the /16 VLAN. I can reach the /24 from a server if I add a static route on the server itself. I have included an attachment that hopefully explains the setup. It is hard to include all the information so please let me know if you need more info. Thank you!
06-11-2007 07:45 AM
This is not an EIGRP problem since the default gateway 10.0.0.1 knows how to get to 10.0.20.0/24
The problem is with the hosts in 10.0.0.0/16 not using the default gateway for 10.0.20.0/24 since ,as you stated, the route is local - so unless you change the subnets, you will have to manually input static routes on each host.
06-11-2007 07:45 AM
How difficult will it be for you to change the subnet mask for the int vlan 910 to a /24 & all machines associated with this ?
06-11-2007 07:49 AM
EIGRP is certainly able to do this. It will track the different prefix lengths and both subnets should be in the routing table. I believe that the issue is that the server is sending an ARP request for the destination address of 10.0.20.x instead of forwarding to the default gateway. I believe that if you were to enable proxy arp that this network would work. As it is the server believes that 10.0.20.x is within the local subnet of 10.0/16 and so it arps for the address directly instead of sending it to the default gateway. If proxy arp were turned on I believe that the gateway would respond to the ARP request and the packet could be forwarded.
HTH
Rick
06-11-2007 07:56 AM
You guys rock! I turned on ip proxy-arp for the 910 VLAN and now I can successfully reach the 920. Thanks you!!
-Rick
06-11-2007 08:07 AM
Rick
I am glad that our discussion was able to help you resolve your problem.
HTH
Rick
06-11-2007 07:51 AM
Thanks for the reply. So by changing the 910 to /24 that should solve my problem? It would be somewhat painful to change all of our 910 devices to the /24 but if that is what we have to do. I wasn't sure if there were some fancy tricks with EIGRP that could produce a workaround.
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