Subject: Routing and signaling across devices with different switching cap abilities

From: "Pandian, Vijay" <[email-masked]>
Date: Fri, 23 Apr 2004 22:54:03 -0400

Consider a mix of devices with varying switching capabilities connected as
follows:

     PSC-1 <===> TDM-1 <===> LSC-1 <===> FSC <===> LSC-2 <===> TDM-2 <===>
PSC-2

Is it fair to assume that PSC-1 and PSC-2 would advertise TE-LSA's with
"PSC" as the switching capability, TDM-1 and TDM-2 would advertise TE-LSA's
with "TDM" as the switching capability, LSC-1 and LSC-2 would advertise
TE-LSA's with "LSC" as the switching capability...?

Given this, would the PSC device (say PSC-1) be able to compute a path using
CSPF to PSC-2?

There had been some discussion regarding the type of label (SUKLM vs. lambda
vs. port) to be used across these switching capabilities. How about the
"LSP-Enc. Type", and "Switching Type" in the Generalized Label Request
Object? How about the Bandwidth Encoding in the SENDER_TSPEC and FLOWSPEC
object?

According to rfc3471, section 3.1.1, the switching type is expected to map
to one of the values advertised for the corresponding link. In that case,
would the LSC-device accept a Generalized Label Request with TDM switching
capability and "port" as the label coming from the TDM capable device?

Any clarification on this is appreciated...

Thanks,

Vijay

PS: During various GMPLS interop events, an additional FSC (and LSC?)
switching capability in the TE-LSA's was required for the end devices to
compute path.

---

From: [email-masked]
Date: Sat, 24 Apr 2004 10:17:57 +0200

hi,

> TE-LSA's with "LSC" as the switching capability...?

what "fair" means in this context ? further the hierarchy refers
to region boundaries as follows:

PSC-1 < PSC-2 < PSC-3 < PSC-4 < L2SC < TDM < LSC < FSC

so assuming you're using different values (non-reported in gmpls- 
routing see below) for TDM and LSC, GMPLS mandates that for inst.
you're crossing region boundary at [TDM,LSC] the LSR at the edge
of the TDM region must capable to find [LSC,TDM], and if such
boundary doesn't exist it is fair to assume that the LSP will not
be established - note that we've specific values for L2SC (51),
TDM (100), LSC (150) and FSC (200) so what are you inferring with
TDM-1 and TDM-2 ?

> Given this, would the PSC device (say PSC-1) be able to compute a path using

well why don't you use the value defined in gmpls-routing, instead
of trying to assess a rule for SC relationship that doesn't exist ?

> Object? How about the Bandwidth Encoding in the SENDER_TSPEC and FLOWSPEC

what's more precisely the question here ?

> capability and "port" as the label coming from the TDM capable device?

i think we've sorted out this issue, during our previous discussion,
and the response is "the LSC interface accepts a Generalized Label 
Request with LSC switching capability and "port" as the label coming 
from the TDM capable device" i guess you mean when crossing the 
[TDM,LSC] boundary

> switching capability in the TE-LSA's was required for the end devices to

yes, because some people didn't quite accurately translated the term 
"port" in their implementation ("port" =/= "physical port" such as a
fiber), but as discussed this is erroneous

hope this clarifies,
- dimitri.
-- 
Papadimitriou Dimitri
E-mail : [email-masked]
E-mail : [email-masked]
Webpage: http://psg.com/~dpapadimitriou/
Address: Fr. Wellesplein 1, B-2018 Antwerpen, Belgium
Phone  : +32 3 240-8491