Subject: MS SPring (BLSR) span TE link

From: "Shiba, Sidney" <[email-masked]>
Date: Mon, 27 Sep 2004 18:30:46 -0500

Hello all,

A while ago (May 2002), there was a mailing thread discussing about how to model a
MS SPring (BLSR) span. At that time Maarten Vissers has stated that a MS SPring
span could or should be modeled as three HOVC links. See attached email below.

Does it mean that a MS SPring span is modeled as three different TE links? Is this still
a common practice? Can anyone point a RFC or draft that covers this use case? 

Your insight is very much appreciated.

Regards,

Sidney Shiba
Fujitsu Network Communications
2801 Telecom Parkway
Richardson, TX 75082

tel: 972 479 6041

---x--- Cut Here ---x--- Cut Here ---x--- Cut Here ---x--- Cut Here ---x--- Cut Here ---x--- Cut Here ---x---
Re: Sonet Ring provisioning
*	To: Suresh Katukam <[email-masked] <mailto:[email-masked]>> 
*	Subject: Re: Sonet Ring provisioning 
*	From: Maarten Vissers <[email-masked] <mailto:[email-masked]>> 
*	Date: Fri, 31 May 2002 14:45:54 +0200 
*	Cc: Zhi-Wei Lin <[email-masked] <mailto:[email-masked]>>, "R. Muralidharan" <[email-masked] <mailto:[email-masked]>>, "Bernstein, Greg" <[email-masked] <mailto:[email-masked]>>, "'Manoj Agiwal'" <[email-masked] <mailto:[email-masked]>>, "'Ccamp (E-mail)" <[email-masked] <mailto:[email-masked]>>, "mpls@UU. <mailto:mpls@UU.> NET (E-mail)" <[email-masked] <mailto:[email-masked]>> 
Suresh,

From the HOVC [STS] layer network the ring provides for HOVC unprotected
connections. I.e. you set up the connection A-B-C-D and inform the MS SPring
[BLSR] ring manager of this connection, and that is it. Some ring managers only
need to be given the ingress and egress nodes, and they will set up the
connection true the ring at the same time as they configure the necessary MS
SPring information in the intermediate switching nodes on the ring.

Because the ring is a MS SPring [BLSR] ring, the HOVC connections are protected.
This MS SPing configuration is however established before any HOVC connection is
routed over it. I.e. it is set up and ready to provide connectivity between its
nodes on the ring. Assume that the ring is a sTM-64 ring. In this case the HOVC
links between any two nodes will have a 32 VC-4 link connections (or 96 VC-3, or
8 VC-4-4c, or 2 VC-4-16c link connections or a mix). 

If extra traffic is supported on this ring then there will be another HOVC link
between any two nodes with the same number of link connections. In this case,
there is a choice to put a connection via the regular HOVC links, or via the
extra traffic HOVC links. In the latter case the connection may get interrupted
when there is a fault in the ring (extra traffic is dropped).

If the ring supports selective MS SPring (NUT feature), then a third HOVC link
between the nodes will exist and the size of the HOVC links is not longer fixed
(in the example to 32). 
I.e. for a sTM-N ring with MS SPring protection
- HOVC link #1 - protected traffic:	0 .. N/2 VC4 link connections
- HOVC link #2 - preemptable traffic:	0 .. N/2 VC4 link connections
- HOVC link #3 - unprotected traffic:	0 .. N VC-4 link connections
Combinations for e.g. STM-64 ring include [link#1, #2, #3]: [32,32,0],
[31,31,2], [30,30,4], etc.

See also the functional model of a MS SPring node in G.783.

Regards,

Maarten