Subject: RE: [Sigtran] sctp-sig-prot

From: [email-masked]
Date: Mon, 1 Jul 2002 16:47:49 +0300

Hi Tolga,

> 1-"Current work in the SIGTRAN Working Group [2719] defines architecture
>    for backhauling SS7 Signalling Protocols over IP.  However, no
>    consideration is given for signaling that is completely terminated in
>    IP networks (sometimes called 'all-IP' or 'full-IP' signaling)."
> Personally I wouldn't agree that no consideration is given in 
> the WG for "all-IP" signalling.

The architecture document does not contain anything about this.  M3UA and
SUA discuss it somewhat, but as current discussions regarding M3UA indicate,
there is not universal agreement on the architecture.

> 2- "The SCTP Handler allows a much lighter protocol stack, optimized for
>    the transport of typical application part protocols (ex: RANAP,
>    RNSAP, BSSAP) over IP. Optimization is possible by removing the not
>    needed and the redundant functionality provided by the signaling
>    protocol stacks."
> Which functionality of the signalling stacks should be considered as
> redundant? For example from a SCCP user point of view, which 
> functionalities in SUA and SCTP are overlapping?

Actually, SUA is not being used by any SDOs to transport things like
RANAP, etc.  My opinion is that if there is no interworking with SS7,
much of the procedures in M3UA and SUA are probably not needed.

Both SUA and M3UA are somewhat verbose protocols, with quite a bit
of overhead, so eliminating them might not be so bad, especially in a simple
peer-to-peer case.

> 3- "SS7 protocols have a different addressing model than IP.  Some layers
>    are hop-by-hop and do not assume global addressing.  It may be
>    reasonable to assume that SS7 addressing will not disappear; however
>    overlaying non-global addressing on top of IP is not a reasonable
>    long-term assumption. In practice, it may be useful to consider SS7
>    addresses as labels, rather than point codes when signaling in an IP
>    network."
> Are we already not interpreting PC+NA as the label of a logical entity,
> whose physical address is one or more IP address+SCTP port?

Interpreting, perhaps.  Personally, I don't like overlaying SS7 addressing
over IP.  There are different point code formats, etc.

Anyhow, I have to run, I will add more details tomorrow.

John

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