VVX Series phones BLF using Broadsoft hosted solution

apokha
Visitor

VVX Series phones BLF using Broadsoft hosted solution

I'm new to VoIP and Polycom, I volunteered to take over the VoIP department when the former engineer resigned on short notice.

I've taken the training and have the Polycom Voice Endpoints certification.

I've worked through many issues so far, but this one has me stumped...

 

When using a large number of BLF entries, we're having an issue with successfully Syncing the BLF lines to the devices.

I've setup multiple devices with 20+ BLF lines in our office and they worked just fine, however when taken off-site the BLFs won't load from a hosted provisioning server.

In the example with my demo phone I was able to configure 32 BLF lines on a VVX 500 series phone with a color expansion cart at our office.

However when I brought it home for further testing, BLFs wouldn't load, I reduced the number of BLF lines to 20 and it's working now.

At the office we use a Watchguard XTM 550 UTM firewall.

At home I'm using a Watchguard XTM 26W UTM firewall.

The network I set this up on at the office was our lab network and was pretty much wide open.

At home I have a network for VoIP with QoS enabled.

 

Question is:  where do I look for the culprit in this BLF issue?  Packet size?  MTU?   Port?

I imagine BLF doesn't use any particular port, does it? Because it still works at home and at other locations, it's just the number of BLFs varies on location.

Furthermore the ISP at both the office and home is the same, except we use a business line at the office, not a residential like I have at home.

Message 1 of 8
7 REPLIES 7
SteffenBaierUK
Polycom Employee & Community Manager

Re: VVX Series phones BLF using Broadsoft hosted solution

Hello apokha,

welcome to the Polycom Community.

It is always useful to include the currently used software version as issue experienced may already be addressed in a newer release.

 

This also allows yourself and others to check against current software release notes.

 

Your issue sound like something I dealt with myself but in order to verify this I would suggest you raise a ticket with Polycom support via your Polycom reseller. Please quote VESC-4126.

 

In my case fragmentation caused the SIP NOTIFY message not being assembled corretly.

 

As a workaround you may want to try :

 

Menu->Settings->Advanced->Network configuration->Ethernet Menu-> Storm filter.

 

Disable the Storm Filter and check again. 


Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.

Best Regards

Steffen Baier

Polycom Global Services

----------------

If official support is required please check how to phone or open a case here

----------------
The title Poly Employee & Community Manager is a community setting and does not reflect my role. I am just a simple volunteer in the community like everybody else. All posts and words are my own & do not represent the views of Employer.

----------------

Notice: This community forum is not an official Poly support resource, thus responses from Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge. If you need immediate and/or official assistance please open a service ticket through your proper support channels.
Please also ensure you always check the VoIP , Video Endpoint , Skype for Business , PSTN or RPM FAQ's
Message 2 of 8
apokha
Visitor

Re: VVX Series phones BLF using Broadsoft hosted solution

Thank you Steffen for the quick reply.

 

I am using UC 4.1.6 as that's the only version that supports the VVX Expansion Module at this time.

 

I will work with storm filtering today and see if that fixes the issue.

 

Also thanks for the tip on SIP NOTIFY, I'll do another packet capture and see if I can find anything useful regarding the sip notify messages.

Message 3 of 8
KL
Advisor

Re: VVX Series phones BLF using Broadsoft hosted solution

Your SIP packets are probably getting fragemented due to UDP size limits. Can you use TCP for the signaling? Use TCPpreffered 

Message 4 of 8
apokha
Visitor

Re: VVX Series phones BLF using Broadsoft hosted solution

Thank you guys for your help, I was able to get it to work late last night, now just need to narrow down what was causing it.

I opened up my lab firewall as much as I could and got 50-some BLF lines to work, now just need to narrow down on the actual culprit.

 

Disabling Storm Filtering didn't fix the issue.

Using TCPpreferred in the config also didn't help.

I'm leaning toward the UDP packet size hypothesis.

 

I will do further testing over the weekend and I'll let you guys know what was the culprit in this scenario once I narrow it down.

Message 5 of 8
KL
Advisor

Re: VVX Series phones BLF using Broadsoft hosted solution

Where did you apply TCPPreffered? I assume you are using an outbound proxy with the Broadsoft? Make sure TCP Preffered is applied for outbound proxy. That will make SIP signaling using TCP to avoid UDP packet frag problems. 

Message 6 of 8
SIP Shaman
Occasional Visitor

Re: VVX Series phones BLF using Broadsoft hosted solution

Sounds absolutely like an MTU issue! Probably because broadsoft/polycom don't support PMTUD. Ouch!

 

 

So one of the modems/routers doesn't support the MTU the broadsoft/polycom jams through it like a fat kid at a hotdog eating contest. And when it comes to polycom.. mums the word. #typical

 

There's a hint this is a known issue from a broadsoft manual: "A UDP datagram of 65507 bytes will have to be fragmented into 45 packets ( Max UDP size of 65507 bytes / UDP size per packet of 1480 bytes ~ 45) to be transmitted across a network. With this many number of fragments, customer firewalls or NAT devices may prohibit the entire packet from being delivered to the endpoint."

 

So if you have BLF Issues, think MTU and fragments! Try other modems and networks! Or buy a snom phone or something!

 

-Brian

 

P.S.

I've seen this MTU issue manifest itself in all kinds of wacky ways. like you send subscribe and get notify but only for <state>terminated<\state> and not for full or whatever the BLF state change is.

 

Some light reading: http://cdn2.hubspot.net/hub/147894/file-1909410432-pdf/docs/Support/Admin_Guides/INVOIP_Connect_-_Mo...

Message 7 of 8
SteffenBaierUK
Polycom Employee & Community Manager

Re: VVX Series phones BLF using Broadsoft hosted solution

Hello SIP Shaman,

welcome to the Polycom Community.

Thanks for commenting on these post's with a possible root cause but without any hard evidence brought up to our support team we are unable to verify this. I am not aware if users in this or the other post you replied to have ever done so.

 

I am personally aware of BLF issues and these, to my knowledge , have been addressed in the past when working with our customers.

 

I rather not speculate on the issues discussed within this or the other post you replied to so if you are currently having an BLF issue yourself please work with your reseller so they can raise a ticket with us.


Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.

Best Regards

Steffen Baier

Polycom Global Services

----------------

If official support is required please check how to phone or open a case here

----------------
The title Poly Employee & Community Manager is a community setting and does not reflect my role. I am just a simple volunteer in the community like everybody else. All posts and words are my own & do not represent the views of Employer.

----------------

Notice: This community forum is not an official Poly support resource, thus responses from Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge. If you need immediate and/or official assistance please open a service ticket through your proper support channels.
Please also ensure you always check the VoIP , Video Endpoint , Skype for Business , PSTN or RPM FAQ's
Message 8 of 8