Nortel Phones drop out randomly

[subbusvce]

hi,

we have a few nortel phones connected to cisco 2960 / 3560 switches. pcs are daisy chained to the phones. for some reason the phones seem to drop out randomly. however on unplugging the cable from the phone and connecting it back seems to resolve the problem. but we dont want our users to be doing this - any idea why this would happen ?

on giving static addresses, the phones seems to be ok. so we set the lease time (dhcp) to infinite but it does not seem to have resolve the problem.

config:

interface range FastEthernet0/1-48
 switchport access vlan 10
 switchport mode access
 switchport voice vlan 20
 spanning-tree portfast
 spanning-tree bpduguard enable
 spanning-tree guard root


Cisco switch acting as DHCP server:

ip dhcp pool VLAN_10
   network 172.22.10.0 255.255.255.0
   default-router 172.22.10.1
   dns-server 172.22.20.20 
   domain-name test
   option 78 ip 172.22.20.62 172.22.20.63
   option 150 ip 172.22.72.10
   option 43 hex f104.ac16.1e28
   option 128 ascii "Nortel-i2004-A,213.48.250.246:5000,1,5;213.48.250.246:5000,
1,5."
   option 191 ascii "VLAN-A:20."
   lease 3

ip dhcp pool Nortel-Voice-20
   network 172.22.20.0 255.255.255.0
   default-router 172.22.20.1
   option 128 ascii "Nortel-i2004-A,213.48.250.246:5000,1,5;213.48.250.246:5000,
1,5."
   option 191 ascii "VLAN-A:20."
   lease infinite



we have no qos applied at the moment. any thoughts appreciated.

Thanks

[Flintstone]

Hi subbusvce and welcome to the forum,

Have you tried using a Sniffer to see if anything is happening at the time of the IP Phones dropping out?

CheerZ and good luck

[subbusvce]

we thought about that but we dont know which phone wuld drop out since they are random. we have connected a sniffer to a phone but that one has not dropped out at all. so no luck on that

[Flintstone]

Hi subbusvce,

Have you also confirmed via the Sniffer that DHCP is working as designed?

CheerZ

[subbusvce]

yes dhcp seems to issue out the ip address. problem is when the phone drops out, it does not seem to get an ip and gets stuck. but when you unplug and replug the cable it then starts to work. strange !!

[Michael McNamara]

Hi subbusvce and welcome to the forums!

Could you please describe "drop out"? The IP phone stops working? The display goes dead? The IP phone reboots? What is the effect on the PC?

Also what model of IP phone and what software/firmware are you running on them?

Good Luck!

[Jon Hurtt]

To add to Michael's Questions,

How many phones do you have connected into each switch?
Are there any other POE Devices connected to the switch?

[subbusvce]

hiya,

when i say drop out, the phones loose connection and they reboot. when they reboot they get stuck and looks like they dont get an ip address. (so we set the lease to infinite thinking the phones get stuck on renewing its ip but this doesnt solve the problem at all)..the pc stop working as soon as the phones drop out.  the phones are nortel i2004 and they run on cisco switch  2960 Version 12.2(46)SE and cisco 3560  Version 12.2(35)SE5.

and John, some switches have around 20 - 30 devices some have a few. its a big campus and they are rolled out as needed. they arent any other PoE devices connected apart from the phones.

again the phones loosing connection is just random and not specific to any model of switch. when we unplug and replug the cable to the phone its gets an ip...also we tested a few phones by giving static address on them and they seem to be fine

Thanks

[Flintstone]

when i say drop out, the phones loose connection and they reboot...

It sounds like that the IP Phone is losing POE as that is the only reason it will reboot but then again you are then saying that you don't have the issue if you use static IPs or is it that you haven't seen the issue on the IP Phone with static IPs yet?

CheerZ

[subbusvce]

i am confused as well...any thoughts micheal ?

[Jon Hurtt]

I would make sure you have enough power for 20-30 Phones in terms of Available PoE Power... Also have you upgraded the phones to the latest firmware?

Also is there anything in the logs on the Switch?

[subbusvce]

the switches are 48 port PoE capable. so i presume they must be having enough power. the phones are running the latest firmware i beleive. i cant see anything on the switch logs..

the strange thing is that we have another site where we have around 20 phones connected a cisco 2960 switch and they seem to be fine...the cisco switch is running a updated firmware than the first site...

but the point the two phones with static address is not rebooting makes me think this is a dhcp issue...but not sure yet

THanks

[subbusvce]

sorry updated news from our telecom team..

i beleive the phones with static address also reboot randomly ...immaterial of weather pc is connected to it or not ? ... so it could not a power issue i suppose...any thoughts?

[Flintstone]

Hi subbusvce,

It looks like a POE issue you are seeing?  Check out this link to troubleshoot the problem and let us know how you get on?

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/troubleshooting/power_over_ethernet.html

CheerZ and good luck

[subbusvce]

Hi,

thanks for the link. i thought about this but then the phones which are connected to external power also seem to reboot...so that makes me think this cant be a power issue..any more thoughts !!