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March 6th, 2014 04:00
Proxy-arp or local-proxy-arp??? Dell Powerconnect 6224
We need to enable some clients to resolve the mac adress of a server which is in another VLAN and ip address range.
I thought that adding the command ip proxy-arp to the vlan interface should do the job, but this command seems to be enabled by default according to the reference guide, after I tried to add the command it is still not shown on a show run. That was confirming my thought. While I was looking for the solution I saw another command which is not listed in de cli reference guide: ip local-proxy-arp. But since I am not sure what this command will do I am cautious to just hit the command on the interface VLAN.
How do others route their arp requests on powerconnect 6224's?
vwijhe
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March 13th, 2014 00:00
After reading my own source again I realized that the thing I want is not possible. It goes beyond the goal of splitting the network into different segment. If all arp request are being forwarded to other networks there is one advantage less: you want to keep broadcast domain small.
Static arp is the thing I'll need to implement to work around this.
Thanks for the clarification anyway.
DELL-Josh Cr
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March 6th, 2014 07:00
Hi,
ip local-proxy-arp is not going to do what you are needing. It tells the switch to respond to all arp requests with its MAC, so that traffic on the same subnet is routed as if it is on a different subnet. This is used if a port is set to protected mode.
If you need to reach a server on a differ VLAN it is going to have to be routed, which the switch can do, but different VLANs are not going to respond to ARP requests from a different subnet.
vwijhe
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March 6th, 2014 22:00
Oh I see I've made a typo in my first post. Routing on the switch is working of course. I'll rewrite my question:
Some clients in vlan 8 need to know the mac address of a server in vlan 1. This can be done by static arp entry, but I want to avoid that workaround because our first server will fail, the second one will have another mac address and the client are not be able to verify the license.
Different vlans are not going to respond to arp requests? A switch should be able to populate the arp table of a client with mac address from clients which are located in other vlans... Proxy arp is invented for clients to get mac addresses of clients which are in another vlan...
http://www.cisco.com/c/en/us/support/docs/ip/dynamic-address-allocation-resolution/13718-5.html
DELL-Josh Cr
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March 7th, 2014 07:00
Yes, that is what proxy arp is for, but the switch is responding to the arp request on behalf of the other client, not a client to client direct communication and needs layer 3 routing, which the way I read the question I wrongly assumed that you wanted to do it at the layer 2 level since you wanted it done at the MAC address level and not the IP address level. Does the software that uses the licenses not use IP addresses to point to the license server? So that the MAC address at that IP would be dynamically learned. What version of the firmware are you at? Some of the older versions had issues with ARP not being forwarded properly.
vwijhe
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March 10th, 2014 02:00
Hi Josh,
The client communicate with the server via it's IP address, the client only verifies the mac-address with the license file, I am not sure why but that's how the application works. If I ping the ip address of the application server, the mac-address is not populated in the mac-address table. I tried to turn of Windows firewall on both sides but that's not solving my problem.
Currently we are running a custom firmware bases on version 3.3.9.1 due some compatibility of out links. The firmware is at least the latest one available. Both mac-address are being populated in the switch but for some reason the switch is not responding to the client requests. If I ping the application server, the switch should give the client the mac-address of the server and the mac-address table of the client should being updated. But it's not...
To make some things clear: layer 3 routing is working perfect, with static arp the application is working fine as well, but I would like to use dynamic arp of course.
Any idea's how I can troubleshoot this?
DELL-Josh Cr
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March 10th, 2014 11:00
Thanks for the extra clarification. I found that proxy-arp only works if routing is not enabled, so that is probably why ip local procy-arp wasn’t being added to running-config. However this also means that there is not a way to do what you want with dynamic entries, only the static method you are currently using.