Cell Relay Archive

["Albert Manfredi" <albert.e.manfredi@boeing.com>]

"kajfas" <kajfas@hotmail.com> wrote:

> Thanks for the reply. I fell pretty comfortable with the RFCs you
> list, but I still look for the answer to my basic question: What
> protocol is used to obtain a dynamic IP address in IPoA, and how is
> the signalling flow between the client and the BRAS (Broadband Remote
> Access Server)?

Then let me try.

RFC 2684, ex-1483, is just a description of optional ways one can
encapsulate IP or other over ATM. Very basic, and doesn't add much in terms
of needed services.

RFC 2225 is a scheme where an IP subnet is assumed to reside *directly* over
an ATM network, connected to a larger internet via standard IP routers,
typically, although there are also ways of bypassing routers if more IP
subnets are built over a contiguous ATM network. So unlike RFC 2683, RFC
2225 goes to some trouble describing all the details (and servers) required
to support normal IP unicast and multicast over an ATM network. (One obvious
example of a needed service is a way to implement IP limited broadcast or
multicast, at a time when the UNI defined was only UNI 3.1. UNI 3.1 does not
support a native ATM broadcast or multicast feature, as Ethernet, FDDI, and
Token Ring do).

LANE v1 and v2 are the ATM Forum's contribution, somewhat similar to RFC
2225, except that LANE doesn't care about anything above the Link Layer. So
where RFC 2225 obsesses over providing an set of standard IP services over
ATM, LANE obsesses about providing a set of Ethernet or Token Ring services
over ATM. If the Link Layer must carry IP, fine. To the IP stack, LANE would
make ATM appear as if it were an Ethernet or a Token Ring LAN.

So, how do you get your IP addresses assigned dynamically? Pretty much the
same as any other IP-over-something scheme. PPP and DHCP ought to be good
choices.

ATM does have its own network management protocol, ILMI, but that's intended
for ATM things, such as allocating ATM addresses.

Hope things haven't changed too much in the past several years, and that my
recollections are good.

Bert