Cell Relay Archive

[Ronald Davis <ronaldd@lucent.com>]

Gazz wrote:
> 
> I would like to find out more information about commercial and vendor
> implementations of B-ICI.  Is it actually implemented and used in
> public
> networks?  What are the alternatives (P-NNI)?  Pointers to examples
> of public networks using B-ICI or equipment supporting it would be
> useful.
> 
> I have found a few reasons but perhaps someone could enlighten me
> as to why there are two different NNI signalling and routing
> architectures - one for private networks and one for public networks.
> 

a slight paradigm shift is in order here.  b-ici is *not* a routing
specification, it is an interface.  routing within a public carrier
network is not subject to standardization.  commercial reasons are
why - public carriers compete on the efficiency with which they route
traffic over their network - the spend a *lot* of time coming up with
ways of doing such things.

pnni came out of the enterprise world - in enterprises you've got
other things on your mind so a standardized routing method is
fine since it allows the enterprise to worry about the things on
which *they* make their money (typically content, &c. - not transport).

> Are there other vendor solutions that anyone knows of for providing
> an interface to a public ATM network with more flexible QoS
> provisioning, ABR support, etc?
> 

so you've got a public network which uses pnni internally.  when you
get to the b-ici you've got a problem because there is a lot of
information which is exchanged between public carriers (and only
between public carriers, i.e. not across a uni) that is by bilateral
agreement.  this kind of information is contained in b-isup messages
but not within pnni messages.  as an example, if you compare a pnni
setup message with the equivalent message that goes across a b-ici,
an iam, you will see what i mean.

so the problem becomes one of how you interwork a pnni network in the
internal network to another (unknown) atm network across a b-ici.
since, as i said, the information exchange is by bilateral agreement
i don't expect to see commercial interworking software available off
the shelf.