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Whats so difficult about ISSU

Our softswitch vendor talks about control plane bandwidths for geo-redundant
configurations on the low end of your numbers.  I'd have to drag out the
slide deck to see exactly what they recommended.


My point is that carrier-class products have demonstrated it's possible.




From: Tim Jackson [mailto:jackson.tim at gmail.com] 
Sent: Monday, November 12, 2012 9:36 AM
To: Kasper Adel
Cc: Frank Bulk; NANOG list
Subject: Re: Whats so difficult about ISSU


I would argue no.

The Class 5 softswitches that are around now are off-the-shelf cPCI or ACTA
hardware running Linux or some other *nix. The TDM -> IP cards are the only
sticky point there to be upgraded, but since everything is a mid-plane, you
can do rolling N:1 upgrades across the cards with minimal (sub 400msec)
impact. There's not a ton special secret sauce there.. 

To the other point, they probably process way more than 2mbps/s of control
traffic during busy hour, especially in geo-redundant configurations as lots
of things have to be synchronized. I think you're talking more on the order
of 50-120mbps..

Yet all of this works pretty damn well.



On Mon, Nov 12, 2012 at 12:21 AM, Kasper Adel <karim.adel at gmail.com> wrote:

Hi Frank,

Is it because C5 softswitches have expensive hardware, advanced software
and dual asics? I would have never imagined that any vendor is capable of
upgrading fpd's/ASICs ucode without a hit unless there are multiple chips
continuously syncing with each other.


On Monday, November 12, 2012, Frank Bulk wrote:

> We do it on our Class 5 softswitch ... and it works consistently.  There
> may
> be a few seconds, once, where a new call can't be made, but most people
> will
> re-dial.  It just works.
> It can be done, but the product has to be built with that in mind.
> Frank
> -----Original Message-----

> From: Kasper Adel [mailto:karim.adel at gmail.com <javascript:;>]
> Sent: Thursday, November 08, 2012 5:23 PM
> To: NANOG list
> Subject: Whats so difficult about ISSU
> Hello,
> We've been hearing about ISSU for so many years and i didnt hear that any
> vendor was able to achieve it yet.
> What is the technical reason behind that?
> If i understand correctly, the way it will be done would be simply to have
> extra ASICs/HW to be able to build dual circuits accessing the same
> and gracefully switch from one to another. Is that right?
> Thanks,
> Kim