Subject: RE: Question about logical link in Link bundling

From: "Fong, Man Wing" <[email-masked]>
Date: Wed, 9 May 2001 10:16:05 -0500

Maarten, 

Very good point and description. The last case that you describe using VC
would be a good alternative to support the bandwidth on demand. Now that the
inverse muxing capability is being transferred from the router to the
transport NEs. In this case, (Debanjan, you're right), the user would use an
OC-12c interface on a router instead of the channelized OC-12 interface to
save cost for this application (BOD). 

Thanks,
Man Wing

 -----Original Message-----
From: 	Maarten Vissers [mailto:[email-masked]] 
Sent:	Wednesday, May 09, 2001 5:06 AM
To:	Debanjan Saha
Cc:	'Fong, Man Wing'; Bala Rajagopalan; [email-masked]; 'Kireeti Kompella';
[email-masked]
Subject:	Re: Question about logical link in Link bundling

 << File: Card for Maarten Vissers >> Debanjan,

Just a thought... those 12 DS3s terminating on the same router (and
providing access to 12 MPLS links) may terminate at the other ends on 12
different routers. With one physical (OC12) interface you have now made
(with the help of the transport network) connections with 12 other
routers. Very cost effective... 

Ofcourse you don't need a DS3 to be present in the STS1 is the router at
the other end of the transport network has a EC1 of (channelised) OC-N
interface. In this case you may deploy direct mapping of MPLS into STS1
payload (via PPP/HDLC or the new GFP encapsulation).

One further cost reduction step (for the case there are e.g. only 5
other routers connected) is to use STS1 virtual concatenation with GFP
encapsulation of MPLS. You can now size each of the 5 STS pipes between
1 and a Xi STS1s (STS-1-Xv) as long as the sum of X1+X2+X3+X4+X5 <= 12.

Regards,

Maarten

Debanjan Saha wrote:
> 
> Fong,
> You're right. A channelize OC-12 can have 12 DS-3s (STS-1)within it.
> However, if all of them are terminating on
> the same LSR, I'm not sure why you'll use a channelized
> OC-12 and not an OC-12c.
> 
> Debanjan

---

From: Maarten Vissers <[email-masked]>
Date: Thu, 10 May 2001 13:42:54 +0200

Man Wing,

The virtual concatenation capability included in the transport NEs is
targeted to support pay-as-you-grow ethernet connections through the
transport network, which ingress/egress the transport network via
physical ethernet interfaces (10M, 100M, 1G, 10G). This capability is
not intended (at least not in today's view) to support an OC12c (STM-4
with VC-4-4c) as ingress/egress physical interface to the transport
network.

The fact that the transport NEs are extended with this virtual
concatenation capability is an intermediate step (early availibility) in
the pay-as-you-grow ethernet connections offer. The final step should
bring the virtual concatenation endpoints to the routers again, such
that in the emerging automatic switched transport network, routers can
dial up additional (or release superfluous) bandwidth, in a hitless
manner (using LCAS from the endpoints).

This will keep the OC12 (in general OC-N) interfaces on the routers
(using VSR optics similar to those used in ehternet today), and removes
the need to perform an additional conversion in the ingress/egress ports
of the transport network (saving costs also here). In addition, the
routers are now again free in selecting the protocol between them
(IP/ethernet, IP/PPP/HDLC, IP/PPP/GFP, MPLS/GFP, IP/ATM, ...) while the
transport network will transparently pass through the virtual
concatenated signal including(its payload with the particular protocol).

Regards,

Maarten

---

From: Maarten Vissers <[email-masked]>
Date: Thu, 10 May 2001 13:42:54 +0200

Man Wing,

Regards,

Maarten