T1/ISDN Resilliency

[TheMitelGuy]

Has anyone heard that Cisco now offers the ability to make a T1/ISDN card resillient? By this I mean, you have one PRI/T1 and that is connected to two T1 Voice Modules in the 1800/2600 and if one card goes bad the second T1 VM instantly picks up? Someone is telling me you can do this now, but I don't see anything on Cisco's site.

 

[whykap]

I have never heard of such thing in any product. Sorry.

 

[jeter]

As a Telco provider we have emergency fail over for multiple circuits but you need two PRI's on site. And if you have two PRI's on site they are going to be redundant to each other and that also depends on how the circuits are setup.


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[trvlr1]

I think AAR is used to reroute calls if one circuit is down, but this will still require 2 circuits and 2 ports.

 

[whykap]

MITELGUY is asking for 1 circuit in 2 ports design.
Dual PRI's designed to failover is pretty common set up but never heard of the above from any manufacturer.
Unless I misread the inquiry.

 

[TheMitelGuy]

No, I think you have it correct. There is only one manufacture that supports 1 PRI and 2 Ports (resillient) and it is Mitel. I had a customer that wanted us to put this feature in on their Cisco, but we have never heard of this on Cisco, only Mitel.

 

[whykap]

Ok let me get this right. What you are saying is MITEL has a solution that you can have 1 voice PRI simultanuously connected to 2 different NSU nodes with one being the primary and one the standby. When the primary NSU fails, standby takes over, with no human interaction or physically moving cables.

 

[TheMitelGuy]

Your statement is one hundred percent correct, buy you can't use NSU nodes, you have to use T1 MMC cards (the cards that fit right into the controller (much the way a WIC would go in a router for Cisco).

From the manual:
The T1/E1 Combo combines trunking and DSP functionality in a single card. The T1/E1 Combo card, available at Release 7.0, provides for resiliency. You must have two 3300 ICPs running Release 7.0 software and a T1/E1 trunk connected to both ICPs. The T1/E1 trunk can fail over to the secondary ICP in the event of a primary ICP failure.

 

[whykap]

Reading this, all it says is that if the main controller fails the T1/E1 card will fail to the secondary controller.
It does not say that if the T1/E1 card fails a second T1/E1 card that already has the same PRI connected to it as the one that fails takes over.
So in Cisco terms if the call manager server that the T1 is registered to fails, it will fail over to another call manager server.
Now that it can do and it always has been able to.

 

[TheMitelGuy]

Actually, the way I described it is how it works. The cards are internal to the Controller, they are not nodes, the card itself does not failover, yet the PRI does.

Cisco would require two routers with a T1 WIC in each. Mitel requires two controllers each with a Failover T1 card. The single PRI gets connected to BOTH controllers. When controller A fails (or the PRI card) it fails over to the second T1 and the second controller. You would not have to swap cords or move the T1 circuit - it's all automatic.

I will take it that Cisco does not suppor this feature.

Thanks.

 

[whykap]

So is there like a special cable that splits the PRI in two locations and its smart enough to only send signal to one end or the other?
That is definately a cool feature.

 

[TheMitelGuy]

The T1 connects to Port 1 on T1-1/Controller1. A cable then goes from Port2 on T1/Controller1 to Port 1/Controller2.

It works very well, but someone was telling me Cisco now does this - I was shocked, I can't find anything, and have a customer that wants to do this.

 

[whykap]

I have not seen or heard of cisco offering that as an option. I don't believe it's feasible unless it is brand new.

I'll research it for sure and get back to you.

 

[jeter]

I put a call in to our Cisco rep and left a message in regards to this question. I hope to get a call back in a few days. Once I hear word I will re-post......


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[whykap]

I can't find anything on cco that would do what you are looking for. However, I also finished reading thru the MITEL reseliency guideline and the reason that MITEL has this feature is the following:
In a dual ICP controller implementation with an MMC T1 card in one of them, if the controller fails and the ip phones failover to the 2nd controller they have no access to the MMC T1 card in the 1st controller, therefore no lines.
To bypass that a second MMC card installed in the 2nd controller with the same PRI connected takes care of that.

That said if the MMC T1 card was to go bad (but no controller failure) on the 1st controller and the 2nd card took over, someone would have to manually failover all the phones to the 2nd controller to still have access to that PRI.
So this design is strictly for controller failure.

Since CISCO does not put Voice modules in its controllers (servers) you can't really compare the features. A server failure in the CISCO world would still allow the rest of the servers to control the same gateway.
I think a router with dual power supplies and dual ethernet connections would provide enough redunduncy for most customers out there.
Now in a situation of a VWIC failure there is no solution besides replacing it, but it sounds to me that MITEL can't do that without manual intervention. Then again I do not install or maintain MITEL so I might be reading this wrong.
This is what I make out from reading the guideline.

BTW i never had a VWIC go bad in the past 9 years. I had out of box failures but not one in production. Usually a power supply or a switch port would cause the router outage, or in a PRI situation, the PRI itself.

I am still interested to see if jeter comes back with something however. It is always interesting to see what other manufacturers offer that cisco does not and vice versa. Usually if there is demand for a feature cisco will incorporate (even if it takes a while).

 

[jeter]

Update, Per our local Cisco rep they have not heard of any new equipment that supports this function. I will try other resources and advise when I can....


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