Subject: Requesting a LSC LSP across a PCS interface

From: <[email-masked]>
Date: Thu, 18 Aug 2005 15:42:31 +0200

Hi all,

Consider the following situation:

       Domain A <= | =>         Domain B         <= | => Domain C
                   |                                |
 [A1]--PSC--[A2]--PSC--[B1]--LSC--[B2]--LSC--[B4]--PSC--[C1]
                   |     |                    |     |
                         |---PSC--[B3]--PSC---|

Suppose I want to setup an (PSC) LSP from [A1] to [C1]. In domain B
there are two options, the PSC route, or the LSC route. Is there a way
to request (or hint for) a LSC LSP in domain B for the A1-C1 LSP? For
example because the quality of the PSC path is deemed insufficient from
the point of view of domains A and C (e.g. A and C are vey high bw LAN
enviroments, B a WAN environment).

Thanks!

cheers,
	Eduard

---

From: dimitri papadimitriou <[email-masked]>
Date: Fri, 19 Aug 2005 00:18:19 +0200

hi,

> enviroments, B a WAN environment).

base on your diagram and assuming symmetric links both nodes B1 and B4 
must have a PSC and LSC switching capability so here and as provided in 
the diagram i assume the boundary is on the node; however, if you mean 
[B1,B4] and [B2,B4] being [PSC,LSC] and [LSC,PSC] resp. then B1 and B4 
are simple PSC nodes with LSC interfaces and then the boundary would be 
on the interface

now, if all domains are in the same routing area
- have strict path all along
- B4 loose hop with explicit indication of incoming interface

if all domains not in the same routing area
- make use of constaint passing by including (or excluding) specific 
switching capability such as to indicate which resource type to 
select/preclude in order to reach the destination B4 (loose hop)

hope this helps,
- dimitri.

> .