The MPLS WG Archive

["Aris Kyriakopoulos" <aris@lucent.com>]

Hi Venkata,

Your explanation below was excellent, and I thank you for your efforts. 
Again, let me make it clear that I am NOT opposed to an MPLS 
implementation allowing static LSPs; giving the operator a choice is a 
good idea for the reasons you mention.  Let me add another application: 
manually set-up traffic engineered LSPs.

Cheers!
-Aris

-- 
Aris Kyriakopoulos
Interoperability Test Engineering, PSAX CO Products
Lucent Technologies
Landover, MD
mobile: (301) 332-2840
office: (301) 809-4509
mailto:aris@lucent.com




"Naidu, Venkata" <Venkata.Naidu@Marconi.com>
04/13/2001 05:34 PM

 
        To:     "'Aris Kyriakopoulos'" <aris@lucent.com>
        cc: 
        Subject:        RE: Does MPLS Require L3 Routing Table ?


Hi Aris

Glad that we are in sync...

> Hi Venkata,
> 
> Thanks for the clarification.  My answer for you is that how 
> well static 
> LSPs will work in an IP world will depend on the 
> implementation.  If you 
> treat your static LSPs as a routing adjacency for OSPF (or 
> whatever your 
> favorite routing protocol is), then they will work just fine. 

Exactly!
 
> However, if you associate static labels with FECs, that's 
> when you lose 
> your ability to really use your L3 routing protocol!  Because 
> what happens 
> if your routing table changes?

But Aris, we can least expect from static LSPs, if the routing table
changes. Consider "static LSPs (for IP switching)" similar to 
"static routing table (for IP routing)" or "static VCs (in ATM 
switching)". 
It is difficult to have static LSPs work along with dynamic routing
changes. To compare well, even traditional dynamic routing protocols
(like OSPF/IS-IS etc) allow room for "static" routing configuration
and expose them as external LSAs. 
Finally we are more intelligent than machines - because we do them.
So do we expect "static" LSP configuration as an option.

> Just as an aside, I have been struggling with the concept of 
> static LSPs 
> myself.  I'm trying very hard to find out what their true 
> utility is, and 
> I have seen very little discussion on the subject, either on 
> the list or 
> in the standards.  I've talked to a couple of people about 
> the subject. 
> Most of the responses, however, have come from the L2 point of view 
> (static LSP = ATM PVC, etc).  For the reasons discussed in my 
> previous 
> e-mail, I'm not comfortable with that analogy.  Your query gave me an 
> opportunity to ask the experts!

Good luck!

Venkata Naidu
--
http://www.geocities.com/kvsnaidu