Whats so difficult about ISSU

Mon Nov 12 15:36:16 UTC 2012

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.

--
Tim

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.
>
> Regards,
> Kim
>
> 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
> memory,
> > and gracefully switch from one to another. Is that right?
> >
> > Thanks,
> > Kim
> >
> >
> >
>