Cell Relay Archive

[rcallon@alpo.casc.com (Ross Callon)]

> > I think that the similarities are pretty large. OSPF and PNNI
> > (and by implication I-PNNI) are all link state routing protocols.
> > Both allow at least two levels of hierarchy (and I think it will
> > be a while before anyone uses more than two levels with PNNI). 
> > By the time that you add connection support and QoS routing 
> > capabilities to OSPF, and also add signalling support, you are 
> > at least a good part of the way to re-inventing PNNI. Also, tag
> > switching does not imply use of any one particular routing protocol, 
> > and I don't see any reason why it couldn't be used with I-PNNI just 
> > as well as with OSPF and BGP. 
> 
> What the fact that both OSPF and PNNI are link state routing protocols
> has to do with similarities between PNNI/I-PNNI and tag switching ?
> After all, as you mentioned yourself, tag switching "does not imply
> use of any one particular routing protocol".

I am thinking of MISR and OSPF as one combination that folks
will use in many cases. Obviously MISR needs to be able to work
with a wide range of routing protocols so this is not the only
combination. There are ways that one could invision using either
that make them seem similar, but there are ways of using them
that make them look different.

I am not sure whether this is a particularly useful discussion 
to take into much detail. I would rather do the technical work. 

> > Finally, there are two big similarities between tag switching and
> > I-PNNI: (i) Both are intended to be open multi-vendor standards. This
> > is a good thing; (ii) Neither of the standards are done yet. 
> 
> In that sense there are plenty of protocols that similar to
> tag switching and PNNI. I somewhat doubt that these kind
> of similarities could be classified as "big".

These were not intended to be stated as protocol similarities. 
Rather, I was stating my opinion that open standards are very
important. Perhaps this paragraph was intended mostly as a sort 
of oblique criticism of any companies which might be tempted to 
avoid participating in the MISR effort (or any other standards 
effort). 

Ross