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troubleshooting Question

Voice \ Data Issues

Avatar of bromley_college
bromley_college asked on
Network AnalysisNetwork Operations
12 Comments1 Solution360 ViewsLast Modified:
HI experts,

We have a strange problem with what at first appeared to be only the ip-phones\ipt vlans.

The phones are Nortel IP handsets (IP 2002 onwards).

The phones will display server unreachable sometimes during the day and voice calls are choppy or drop.  Sometimes the phone rings by itself on a higher ring tone even when no-one is calling that dn.

The nortel engineer update firmware etc but today I noticed that...

When the phone dropped (sometimes just goes back to NODE: on display), I lost 2 pings to a server.  This suggests that it is not a problem with the phone system but the data network.

QoS is seup and correctly marking voice packets with cos voice dscp ef, the core trusts these mkarking and the distribution layers use acls to qos source and dest, although priority trust from source would work too at this layer.

To explain our setup is quite difficult, I can attach a visso diagram if that helps.

Each distribution switch holds local vlans and then routes off the core for coross campus traffic.


New area 1:
VLAN 3 Router

Core - vlan 3 router vlan
However core also has old networks on that we are in the process of getting rid of, vlan1  data, vlan 2 student, vlan 160 ipt (core prioritises macs of vlan 160 using acls

The prblem seems to happen campus wide but I think one end of the call is always on the old vlan for ipt (vlan 160).

Using wireshark when the phone dropped and I lost 2 pings showed nothing. (Pings are never lost to our servers normally, only when the phone dropped) ps: my pc is not on my phone, I have a dedicated 1gbps connection on another switch.

We use 3com switches, 5500G, 5500-PWR

Any help would be greatly recieved.
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