[cisco-voip] MWI Collisions

[Pat Hayes]

The 25% allocation is a bit of an old recommendation, based mostly on 
PBXs where an MWI attempt take a a while to dial out. Take a look at a 
callmanager integration, watch in port status monitor during a resync, 
when things are moving as fast as they can, how long your MWIs take to 
dial out and how many ports they use. They complete in a fraction of a 
second, and even on busy 96 port systems, you'd be hard pressed to see 
Unity need more than 4 ports for MWI dialout. At 25%, you'd be 
dedicating 24 ports. The limiting factor is really how fast exchange can 
pump the data to exchange. Not trying to tell you guys you need to 
change everything, just something to consider.

These days, I usually suggest around 15-20% total, depending on usage 
patterns, but to also designate those ports for TRaP and notification 
dial out as well. That way you've got all of your outdialing happening 
in one block, which you of course exclude from your line group. I'm not 
sure what the latest design guide says, but it'd be worth a look.

As for Joel's original question, could you provide a little more detail 
on the configuration? I assume since we're talking about Unity and calls 
  through your PRI not completing that these calls route through Unity 
initially? During that same period, could internal users call Unity? 
What version of Unity? Callmanager (or CME?)? What version of TSP on Unity?

-------- Original Message  --------
From: Joel Perez <tman701 at gmail.com>
To: "Jorge L. Rodriguez Aguila" <jorge.rodriguez at netxar.com>
Cc: "cisco-voip at puck.nether.net" <cisco-voip at puck.nether.net>
Subject: [cisco-voip] MWI Collisions
Date: 3/12/2008 12:31 PM

> Hey Jorge,
> 
> Actually I do have 25% of my ports assigned to only MWI and they arent part of the VMHuntGroup.
> That is why i opened up the TAC case. Calls should not be going to these ports at all.
> Im kinda going to guess that since the ports between Unity/CUCM de-registered at around the same time then that would cause Unity to use any available registered ports for inbound calls also. But that is only a guess, still waiting on TAC to get back to me.
> 
> Joel P
> 
> 
> On 3/12/08, Jorge L. Rodriguez Aguila <jorge.rodriguez at netxar.com<mailto:jorge.rodriguez at netxar.com>> wrote:
> 
> Do you have Dedicated MWI ports? It looks like you don't. As a rule of thumb, you should dedicate 25% of your ports to MWI, Meaning you do not send calls to these ports on the auto attendant Hunt Group. On the Unity, you should also set them to MWI only. This Should fix your problem. Keep in mind that by doing this you are effectively reducing the amount of port that will answer and depending on you port usage, you could be in need of adding ports. Set up 4 ports for mwi and 12 for Voice calls, If 12 is not enough, your next step should be to add ports, no to reduce the amount of MWI dedicated ports.
> 
> 
> 
> Hope this Helps;
> 
> 
> 
> 
> 
> Jorge Rodríguez Aguila
> 
> CCNA,CCVP
> 
> Senior Network Consultant
> 
> Netxar Technologies
> 
> jorge.rodriguez at netxar.com<mailto:jorge.rodriguez at netxar.com>
> 
> Office 787-765-0058
> 
> PCS 787-688-8530
> 
> [cid:image001.png at 01C88434.9CDB9060]
> 
> 
> 
> 
> 
> 
> 
> From: cisco-voip-bounces at puck.nether.net<mailto:cisco-voip-bounces at puck.nether.net> [mailto:cisco-voip-bounces at puck.nether.net<mailto:cisco-voip-bounces at puck.nether.net>] On Behalf Of Todd Franklin
> Sent: Wednesday, March 12, 2008 9:39 AM
> To: cisco-voip at puck.nether.net<mailto:cisco-voip at puck.nether.net>
> Subject: [cisco-voip] MWI Collisions
> 
> 
> 
> Yesterday we had a failure with the system whereby calls coming in on the PRI were not happening, but we could call out on the PRI.
> The entire event lasted maybe 15 minutes.
> When I looked at the Unity event viewer, I see many THOUSANDS of these during that timeframe (on average it looks like 60 every second were logged):
> 
> "Cisco Unity-CM TSP device 20 (Cisco Unity port 16): An attempt to turn ON the message waiting indicator (MWI) for extension 1212 failed because a collision occurred with an incoming call on the same port.
> 
> The MWI request will be retried. But to prevent collisions, we recommend that ports setting MWIs be isolated from ports handling incoming calls. If the MWI status remains unchanged for an extended period of time or if there are many of these warnings from Cisco Unity in a short period of time, there may be an MWI misconfiguration or another problem."
> 
> ---
> 
> Any ideas anyone?  Unity looks quiet today, but this was a bizarre failure right out of the blue.  If I need to do something to avoid a repeat of this, I'm more than willing!!
> 
> Thanks!
> 
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