Mailing List Archive

non-concatenated STM-4 on Junipers
First of all, let me say I don't really have too much personal
experience with SDH/SONET on a transmission level, so excuse me if this
question is stupid. :)

I'd like to provision an STM-4 over an existing STM-16 SDH-ring to
connect a couple of M40's in two POPs, since I happen to have some
1-port OC-12 PICs available and the capacity is currently unused on the
ring.

The problem is that the ADMs used on this ring can not add/drop a
concatenated STM-4, only non-concatenated (i.e. on the STM-4 ports it
can only drop 4 x VC-4, not a VC-4-4c). In fact, there are not tribs
available for this particular ADM platform who can do concatenation on
STM-4 level, so we'd have to replace the ADMs if we want to deliver
concatenated STM-4's on them. This currently seems to be a show-stopper,
since most router linecards don't seem to handle non-concatenated SDH
circuits.

However when I looked at the specs for the 1-port OC-12 PIC's, they say
"operates in both concatenated and non-concatenated mode", so I'm
suddenly seeing a tiny spark of hope. But does that mean I need to set
the "no-concatenation" sonet-option on the PIC and be presented with
four STM-1 channels, or will it actually do concatenation internally on
the PIC and present me with a full STM-4 on the Juniper?

If given four STM-1 channels, I suppose we could configure a "SONET
aggregated interface" in the software and re-bundle the channels
logically, but I'd obviously prefer to be presented with a single STM-4
interface. Is this possible without concatenation being done on the
ADMs?

Hopefully someone who is a bit more clueful about SDH (and the Juniper
SONET PICs) than myself know more about this?

/leg
non-concatenated STM-4 on Junipers [ In reply to ]
On Mon, Feb 10, 2003 at 08:07:38PM +0100, Lars Erik Gullerud wrote:
> However when I looked at the specs for the 1-port OC-12 PIC's, they say
> "operates in both concatenated and non-concatenated mode", so I'm
> suddenly seeing a tiny spark of hope. But does that mean I need to set
> the "no-concatenation" sonet-option on the PIC and be presented with
> four STM-1 channels,

Correct. This looks like:

so-1/2/0:0 up up
so-1/2/0:0.0 up up
so-1/2/0:1 up up
so-1/2/0:1.0 up up
so-1/2/0:2 up up
so-1/2/0:2.0 up up
so-1/2/0:3 up up
so-1/2/0:3.0 up up

BTW... this also happened because the carrier wasn't able to
deliver STM4c with his equipment. :-)

> or will it actually do concatenation internally on
> the PIC and present me with a full STM-4 on the Juniper?

No.

> If given four STM-1 channels, I suppose we could configure a "SONET
> aggregated interface" in the software and re-bundle the channels
> logically,

Yep, but only starting in JunOS 5.6.

> but I'd obviously prefer to be presented with a single STM-4
> interface. Is this possible without concatenation being done on the
> ADMs?

No.


Best regards,
Daniel
non-concatenated STM-4 on Junipers [ In reply to ]
On Mon, Feb 10, 2003 at 08:25:11PM +0100, Daniel Roesen wrote:

[cut]

> BTW... this also happened because the carrier wasn't able to
> deliver STM4c with his equipment. :-)

Ugh, STM4c vs STM4. Now that you've mentioned it, I do recall seeing a "c"
notion before but have never paid attention to it (serves me right, and
*now* I know what "VC4" is, too. ;^) ). This has bitten us in the bum also,
and we were extremely surprised to find out that our SDH vendor (one of the
biggest ones there are) had to *manufacture* concatenated STM4 cards
especially for our deployment.

> > If given four STM-1 channels, I suppose we could configure a "SONET
> > aggregated interface" in the software and re-bundle the channels
> > logically,
> Yep, but only starting in JunOS 5.6.

Have you tried this, by the way? I seem to recall that logical concatenation
is done using Juniper's load sharing, and if you don't have enough FECs for
it to work well enough, you may never get to the true capacity of the full
STM4.

SY,
--
D.K.
non-concatenated STM-4 on Junipers [ In reply to ]
On Tue, Feb 11, 2003 at 09:58:47AM +1100, Dmitri Kalintsev wrote:
> > > If given four STM-1 channels, I suppose we could configure a "SONET
> > > aggregated interface" in the software and re-bundle the channels
> > > logically,
> > Yep, but only starting in JunOS 5.6.
>
> Have you tried this, by the way?

No.


Regards,
Daniel