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SGE2010P - Problems with ARP Replies

I'm hoping I can explain this coherently.  I have Polycom IP phones connected to a SGE2010P.  The SGE2010P in turn connects to a Cisco 3650G.  The IP PBX in turn connects to the Cisco 3650G.

This we will call Exhibit A

Phones -> SGE2010P -> Cisco 3650G -> IP PBX

There are also other  IP phones behind a Cisco 2950T, also behind Cisco 3650G.

This we will call Exhibit B

Phones -> Cisco 2950T-A -> Cisco 3650G -> IP PBX

The situation I have is this:  All the phones in Exhibit B can communicate just fine with the IP PBX.  However, all the phones in Exhibit A can initialize their connection, but the server cannot properly reply.  I have discovered that the server is not receiving ARP replies from the IP phones behind the SGE2010P.

Now, here's the interesting thing.  When I put a computer on the same VLAN on yet another switch behind SGE2010P and start packet sniffing to try to troubleshoot, now all of a sudden the server is receiving the ARP replies from the phones behind the SGE2010P.  When the computer removed, the server loses the ARP resolution again when it times out.  When the computer is re-added, ARP replies are received once again.  Pinging the phones is also impossible obviously, since there is no MAC associated with the IP in ARP.

Exhibit C shows how the computer is connected

Sniffing Computer -> Cisco 2950T-B -> SGE2010P

I'm quite at a loss at:

1) Why ARP replies aren't getting to the server

2) Why packet sniffing on a completely different switch further back from the server than the phones incite the ARP replies to reach the server.

This work around of sniffing to get the replies to work is also no acceptable.  I desperately need some assistance in getting this resolved.


1) I have not changed STP settings

2) All the phones connect to the VLAN using Tagged VLAN's.

3) The server and the sniffing computer connect to the phone VLAN untagged.

4) There is no bridging with this VLAN.  The VLAN is isolated from any routing.

5) The SGE2010P is a cluster of 2.  The firmware on SGE2010P cluster is and for primary and secondary respectively. (Yes I plan to upgrade the firmware to

Will a brilliant person please step forward.



Problem has been resolved by turning off VTP Pruning (under VLAN Properties on CNA) on the Cisco switch that is trunked between the phone server and SGE2010P.

This apparently functioned previously because there used to be a phone on a 2950T connected to the SGE2010P.  However, when the sole phone on the 2950T was removed, the 2950T and 3560G decided that the phone VLAN was no longer in use and pruned it off.  This is because the SGE2010P is apparently transparent to the enterprise switches and ignored the prescense of the other phones on the VLAN.  As such, stopping the switch from pruning vlans any further now allows the VLAN's to continue to be actively pushing around data that otherwise would have been pruned out.