[asterisk-ss7] Single Point Code across Multiple * Boxes.

[Matthew Fredrickson]

Amish Chana wrote:
> Hi,
>>> Hi Matthew,
>>>
>>> In this case, if the point code is distributed across more than one box, 
>>> how do you manage SS7 link (and linkset) failures, where the messages 
>>> need to be re-routed via another link (or linkset) during failure scenarios?
>> Well, to have a fully redundant setup, you would have separate boxes 
>> terminating each signaling link.  These routing machines can masquerade 
>> ISUP traffic over to other machines via IP protocol based links.  Each 
>> of these IP connected boxes has an IP link to each box with a physical 
>> signaling link.  If a machine with a physical link goes down, it reports 
>> it to the IP links that are hooked up to it and the machines using those 
>> IP links use their alternate IP links instead of that link, providing 
>> for redundancy in times of link failure.
> Have you looked at the RSerPool 
> (http://www.ietf.org/html.charters/rserpool-charter.html). It may be one 
> method of addressing these requirements.

I actually have seen a number of different projects like this for 
cluster distribution, management, and synchronization.

> 
>> There are going to be other problems to think about as well, but I think 
>> that the basic logic is sound and will work.
>>
>> I actually just got masqueraded ISUP messages passing correctly back and 
>> forth over IP, but I still have some technical hurdles as far as what to 
>> do as IP links go in and out of service.  This list will definitely know 
>> what I have something I'm interested in testing :-)
> What about using M3UA to address the requirement of having one point 
> code across more than one box? The Routing Key registration method 
> provided for in M3UA will allow each box to register the CIC values for 
> which they want to receive ISUP messages. See the example architecture 
> with M3U1 below. Box1 (ASP1) would register a routing key for CIC 1..93, 
> Box2 (ASP2) would register a routing key for CIC 94..186, and Box3 
> (ASP3) would register a routing key for CIC 187..279. The E1s/T1s from 
> each SEP to each Box/ASP would still exist, however we would terminate 
> the SS7 on a Signalling Gateway and route M3UA between the SG and each 
> ASP. (The example below shows one SG but at least 2 will be necessary).
> 
>                                                               ----
>                                                             /      \
>                                                        /---+  ASP1  |
>                                                       /     \      /
>                                 SG                   /        ----
>                                +---------------+    /
>                                |          |    |---/          ----
>         +-------+   SS7 links  |          |    |            /      \
>         |  SEP  +--------------| SS7 Ntwk.|M3UA+-----------+  ASP2  |
>         +-------+              |          |    |            \      /
>                                |          |    |              ----
>                                |          |    |---\
>                                +---------------+    \         ----
>                                                      \      /      \
>                                                       \----+  ASP3  |
>                                                             \      /
>                                                               ----

Although I am not using true M3UA and sigtran protocols right now, 
conceptually, this is almost exactly what we are doing, except we will 
support multiple SGs to each ASP as well.

Matthew Fredrickson
Digium, Inc.