Michael McNamara

technology, networking, virtualization and IP telephony

Nortel IP Phones Broadcast Storm Advisory

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i2002_ip_phoneYou’re going to have to read this document for yourself. Somehow its possible for an i2002, i2004, i2007, 1120e, 1140e and 1150e to throw a loop into the network when the devices are powered by external power supplies as opposed to using a PoE (Power Over Ethernet) switch.

As a rule of thumb I enable Spanning Tree with Fast Learning on all our edge switches since the auto MDI-X feature makes it very easy for a user or inattentive network engineer to physically put a loop in the connect by connecting to edge ports with the same patch cable.

Cheers!

Update: Thursday December 18, 2008

I’ve fixed the broken link above… Thanks Bob!

Link Flap and Succession Voice Gateway Media Cards

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The Nortel Ethernet Routing Switch 8600 supports a feature called link flap detect. This feature is designed to detect a port whose link is flapping up and down and potentially disable the port and/or issue an SNMP trap. The feature allows the configuration of a specific frequency and interval which can be used to fine tune control of the feature.

A few years ago we deployed about 25 Voice Gateway Media Cards (VGMC) across five different Nortel Call Server 1000Ms. We almost immediately started to notice a problem between the VGMCs and the ERS 8600 switches. The VGMCs would link up and link down multiple times as they booted up. While there is technically no real problem with the VGMC you can run straight into a road block if you reboot the card multiple times in a short period of time. Without getting to crazy on the explanation the ERS 8600 switch would potentially disable the switch port(s) that connected to the VGMCs if they were rebooted to often during a 60 minute period. The problem was only observed while the VGMCs were booting up, once the VGMC was up and running the problem never occurred. I believe the link flap detect feature is enabled by default unless specifically disabled.

This may be an old problem that might have already been corrected by Nortel but I still have the link flap detect feature disabled on the Ethernet Routing Switch 8600s that connect to our Nortel Voice Gateway Media Cards.

ERS8600:5# config sys link-flap-detect interval 60
ERS8600:5# config sys link-flap-detect frequency 10
ERS8600:5# config sys link-flap-detect auto-port-down disable
ERS8600:5# config sys link-flap-detect send-trap enable

The configuration can be confirmed using the following command;

ERS8600:5# show sys link-flap-detect general-info

Auto Port Down: enable
Send Trap : enable
Interval : 60
Frequency : 10

The frequency defines how often a port can go down, where the default is 10 (times). The default interval is 60 minutes; therefore the port will be disabled if the port goes down 10 times within 60 minutes.

Cheers!

Nortel IP 2050 Softphone and Windows Vista

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ip_softphone_2050_317x474 Nortel has just released a support bulletin documenting a problem (CR Q1863946) between the Nortel IP 2050 v2 (and v1.4) and Windows Vista that can affect the audio quality. Nortel is advising users to modify the audio quality within the IP 2050 Softphone application (File -> Settings -> Audio) to a setting of 4 or higher. Nortel IP 2050 v1.4 users must also use the Vista Service Manager to disable QoS on the desktop/laptop. There is no mention of the IP 2050 v3 Softphone in the bulletin so I would guess that version is not affected.

We’ve been using the IP 2050 v2 for connecting to our Nortel Succession 1000M Call Servers with very good success. It’s very reliable and the audio quality has been excellent. I should point out that we lease our corporate laptops with a 24 month refresh so we always have decent hardware to work with. And it doesn’t hurt when you have a Gigabit network backbone from Nortel of course.

We’ve held off deploying the IP 2050 v3 because of the new licensing server that is required although we can’t fault Nortel for moving towards such a solution. While we’ve been very honest in our purchasing and deploying of the IP 2050 softphone I can only guess how many others out there haven’t been so honest. If you’re interested in the Nortel IP 2050 just don’t forget that you’ll need to purchase a copy of the Nortel IP 2050 software along with an Internet IP User ISM (license) for each user.

You may also want to evaluate Microsoft Office Communications Server before you deploy the IP 2050 in any large numbers. We’ve started testing OCS in our lab and we’re hoping to start evaluating it’s voice and video conferencing capabilities in the next few months. You’ll probably still want to use the Nortel IP 2050 Softphone for any Nortel Contact Center (Symposium) agents but for basic voice, instant messaging and video conferencing OCS looks very promising.

Cheers!

What does "watchdog timeout" mean on Nortel wireless phones?

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wlan_handset_2210_600x400I’ve been working with Motorola and Nortel for over the past 9 months troubleshooting an issue that was causing the Nortel wireless phones (2210, 2211, 6120, 6140) to reset while the phone was idle. We eventually traced the problem to a buffer overload issue on the AP300 due to the extreme chattiness of the Spectralink Voice Priority (SVP) and UNIStim protocols and the prolonged power save polling (1.5 seconds) of the Nortel wireless phones. Motorola just released v1.2.0.0 and v3.2.0.0 software for the RFS7000 and WS5100 respectively that resolves this problem by increasing the buffer space on the AP300 allocated per (voice) mobile units. Thanks to Nortel and Motorola for their diligent work in tracking down this “needle in a haystack”.

It was a challenge to understand all the different heartbeats, timeouts and protocols that were in play between the handset and the Nortel 2245 wireless gateway and ultimately the Nortel Succession Signaling Server. With any Nortel IP phone running a UNIStim protocol there is a watchdog timer on the phone that counts down from 200 seconds. The watchdog timer must be reset by a watchdog reset (heartbeat) message that gets sent out from the Nortel Succession Signaling Server. This watchdog reset gets sent every 30 seconds. If a handset, remember now any Nortel IP handset that is running a UNIStim protocol such as the i2002, i2004, 1120e, 1140e, 1150e, 2210, 2211, 6120 and 6140 misses too many of these heartbeats the phone will reset itself usually displaying the message “watchdog timeout” indicating that the watchdog timer has reached zero and the phone is attempting to recover from the problem by resetting itself. With the Nortel 2210, 2211, 6120 and 6140 you also have the SVP heartbeats and timeouts to worry about.

If you have some IP phones that are generating “watchdog timeout” message your probably loosing packets somewhere in your network. With that said I would advise anyone with such a problem to immediately contact their voice reseller and make sure their Succession Call Server and Signaling Server have the latest and greatest DEP (patches) list. Once that’s complete you’ll need to go about the task of isolating the possible locations where you could be dropping packets. If it’s a wired IP phone then the problem is much easier to troubleshoot and isolate. If it’s a wireless phone then you’ll have a few extra steps. You’ll obviously need to make sure that you have QoS (DiffServ) up and working within your environment and you’ll need to make sure that you have SVP support enabled on your wireless infrastructure. SpectraLink (recently acquired by Polycom) actually has a library of documents to help customers configure their wireless infrastructure properly to support the SpectraLink handsets.

Cheers!

Correction: August 19, 2008
The watch dog interval is actually 200 seconds long and not 120 seconds as originally posted.

Update: August 24, 2008
It would seem that this article has generated a lot of interest including several inquiries by Nortel. So I thought I would try to add some additional explanation to help more clearly describe the problems and experiences I’ve had the Nortel 2211 and 2210 wireless handsets. I won’t rewrite the original because I don’t think there is anything wrong with it, other than perhaps missing some attention to the specific details.

The Motorola WS5100 v3.x and RFS7000 v1.1 was technically broken for anyone using the Nortel 2211/2210/6120/6140 wireless handsets. The phones would often reset while idle, because of a buffering issue on the Motorola AP300 access port. These problems have been resolved (as far as my testing indicates) in the Motorola WS5100 v3.2 and RFS7000 v1.2 software release. Through our troubleshooting of this problem we learned a great deal about the Spectralink Voice Priority protocol and the UNIStim protocol. In short the Nortel wireless handsets will go into PSP (Power Save Polling) for approximately 1.5 seconds, during that time the wireless handset turns off it’s radio to help save power and preserve the battery life. The problem occurs while the phone is idle because of the PSP mode, this is why no problems are ever reported while the phone is off-hook and actively being used. While the wireless handset is in PSP mode the wireless network is responsible for buffering any packets that are sent to the handset. The SVP protocol and UNIStim protocol can generate a lot of packets causing the wireless network to discard some packets while the phone is in PSP mode. These discarded packets can, depending entirely on the timing, cause the phone to either reset or the phone to be unregistered from the Succession Signaling server.

I’ve been asked by quite a few people what can be done to help alleviate any potential issues?

  • The wireless infrastructure should be configured to support the SVP protocol
  • QoS (DiffServ) should be set to “Trusted” on every Ethernet switch port that will be used to connect the different equipment (Succession Signaling Server, Succession Voice Gateway Media Card, 2245, wireless infrastructure)
  • Design the wireless infrastructure so there is at least -60 dB of signal available and no more than 7 wireless handsets connected to a single access point/access port.

With all that said Nortel has literally just released v97.072 software for the Nortel 2211/2210 wireless handsets. While the release notes don’t seem to indicate any changes that are specific to “watchdog” issues it might be worth giving it a shot.

Cheers!

Update: Friday September 12, 2008
I’ve placed a copy of the Nortel document WLAN IP Telephony Installation and Commissioning (v3.3) on my website. This document should be a great help to many folks that are having issues with Nortel 22×0 and 61×0 wireless handsets.

DHCP Parse Error

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It would seem a great many people are running into this error so I thought I would post a quick article that would help all those looking for a solution to their problem. The Nortel i2002/i2004 (any Nortel IP phone) will return the error “DHCP parse error” if the DHCP server returns DHCP option 128 with an invalid format.

In one of my first blog posts entitled “DHCP Options (VoIP)” I outlined the DHCP options and the format that the phone expected. Kenneth quickly pointed out that I had fat-fingered the example DHCP string omitting the semicolon between the values for the primary Call Server (S1) and the secondary Call Server (S2). (I’ve since fixed the original post)

Here’s the format the DHCP option code 128 which the IP phones expects to be returned from the DHCP server when the IP phone is configured for “Full DHCP”;

Nortel-i2004-A,iii.iii.iii.iii:ppppp,aaa,rrr;iii.iii.iii.iii:ppppp,aaa,rrr.

Where the following values are;

  • “Nortel-i2004-A” = Option #128 begins with this string for all Nortel IP phones
  • “iii.iii.iii.iii” = the IP Address of the Call Server (S1 or S2)
  • “ppppp” = port number for the Call Server
  • “aaa” = the Action for the Server
  • “rrr” = the Retry Count for the Server

The IP Address must be separated from the port number by a colon (:). The parameters for the Primary (S1) and the Secondary (S2) Call Servers are separated by a semicolon (;). The string must end a period (.).

If you are using an ISC DHCP server (this is generally included with any of the Linux distributions) you can refer to my article entitled “ISC DHCP Server (Nortel VoIP)” for information on how to setup and configure the ISC DHCP server to work with Nortel IP Telephony.

Cheers!

Update: Wednesday January 28, 2009

I just came across a “DHCP Parse Error” that actually had nothing to-do with the DHCP string. We had a phone that was using the same DHCP template as 9 other i2002 phones but it was displaying “DHCP Parse Error” when it booted up (this only surfaced after we upgraded to 0604DCG). The phone was actually configured incorrectly. It was suppose to be configured for a Voice VLAN and configured to get the Voice VLAN via LLDP-MED. The LLDP-MED option had been left set at “0” (disabled) so the phone was trying to make a DHCP request looking for Option 191 while the DHCP server was only configured to return Option 128 as detailed above. It only took a few minutes to fix but I can see how someone could spend hours stuck on this.

Cheers!

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