PC through IP Phone works for 20 seconds during phone boot

[professorguy]

I have a Mitel 5212 IP Phone into a 3560. Then a PC daisy-chained through the phone port.

Here's what the port looks like:

interface FastEthernet0/1
description IP PHONE + PC
switchport access vlan 200
switchport mode access
switchport voice vlan 7
mls qos trust cos
spanning-tree portfast
!

I boot the PC, then plug it into the phone and then boot the phone. During the approximately 20 seconds it takes the PHONE to boot, the PC works fine. It can do DHCP, see the network, surf the web, etc. As soon as the phone comes up completely, the PC is cut off. Can't see its gateway, can't renew its IP, can't surf, etc. and it stays off the network.

After the boot, the phone can show the port settings for the PC and they all look good (100Mbps, full duplex, cos=0, etc).

Any ideas?

 

[helpdeskdan]

Is the phone correctly trunking to the switch? Have you tried checking with a show fa0/1 switchport?

 

[professorguy]

The phone works great. It finds its own DHCP Server and correctly pulls an appropriate IP. It can make and receive calls and the quality seems fine.

The interface seems perfect:

FastEthernet0/1 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0019.e89e.9386 (bia 0019.e89e.9386)
Description: IP PHONE + PC
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 10/100BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:04, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 1000 bits/sec, 1 packets/sec
2978 packets input, 383507 bytes, 0 no buffer
Received 899 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 843 multicast, 0 pause input
0 input packets with dribble condition detected
26914 packets output, 6921096 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out

 

[helpdeskdan]

That's good to know, but not quite the command I wanted & also I typed it wrong.
show interface fa0/1 switchport

 

[professorguy]

Turns out the Mitel server has a database (each record is a phone) which has a filed called "COS" (class of service). This is not to be confused with Cisco's cos. The COS number in Mitel's db is an index into another table which actually holds the internal configuration of the phone. Once a phone boots, the last step is to have the configuration downloaded into the set.

Our testing revealed one phone worked correctly, others didn't. Looking at the supplimental table revealed that one class of service had the PC 2nd port ENABLED and a different class had it DISABLED (actually didn't have any setting for it but disabled is default). And the phone that worked had the index of the ENABLED class in the OCS field...those that didn't used a different class (from a setting for older phones here).

Changing the COS to the correct index solved the problem lickety-split. There's a few hours of my life I'm never getting back....

 

[helpdeskdan]

Thanks for sharing the information