The IP over ATM Mailing List Archive by date

[<P82609@vnet.atea.be> (Lode Coene)]

bryang@eng.adaptec.com (Bryan Gleeson x3228) Wrote:
| 
| 
| Lode,
| 
| >The routing of that message is based on the digits of 
| >the universal number(take 1-800-GLEESON).  The orignator 
| node put the number 
| >in the message and the network layer of the orginator 
| node(=A) will translate 
| >this number based on the first 2 or 3 digits to a 
| pointcode, of a node(B) 
| >which the originator node thinks is nearer to the final 
| destination(=D)....
| 
| >Now the message is routed using the generated pointcode 
| to the  B node( just 
| >the same as IP does with its DPC, OPC is left alone). 
| When the message arrives 
| >in the B nodes then ihe networklayer will find that this 
| is not the final 
| >destination, so yet another translation is performed on 
| the number, yielding 
| >another pointcode(this time of the node C) The rules to 
| which this translation 
| >confirms are under the discretion of the network operator 
| ...
| 
| >Now in C the we cross a 
| >network border, that means  we are going from one 
| operator to another operator 
| >network Here also a translation is done on the called 
| part addres(=destination 
| >number), but the calling party address of node A  is also 
| changed, because 
| >otherwise the return message would not be able to find A 
| back....
| >
| 
| Let's see if I have this right. Database updates and 
| queries are made using a full 
| transaction protocol / remote operations / SCCP / MTP 
| stack. To progress a
| query or update towards the database, (or indeed any 
| message)  there are multiple 
| global title -> next hop point code translations performed 
| along the way, by the SCCP 
| layer, using a predefined table of some sort at each 
| sigalling point to do this 
| translation.  At an administrative boundary a "new" 
| request is generated which is in 
| effect chained to the old one.
 
At a administrative boundary, the request is not generated "new". The request 
is contained in the user data of the message(and is never touched till it 
reaches the application in the final endnode), but the called party address of 
the SCCP header is examined(and indeed starts of at the originator node as the 
number given by  the application), translated(to MTP pointcode) and 
changed(add , remove, insert digits) and the calling party address(of the SCCP 
header) is changed(add, remove, insert digits). So nothing is chained(as I 
seem to understand this) to the message, only the routing info contained in 
the SCCP header is changed/transformed. 

As for the rest, you 've got the picture. 
| 
| If anything the closest thing to IP -> ATM address mapping 
| is the global title to
| point code mapping, rather than the 800 number to current 
| location number, which
| I guess is translating one global title into another and 
| is more like a DNS name 
| to IP address mapping.

Correct.

| 
| (BTW what does all this next-hop determination and chained 
| requests at boundaries
| remind you of :-)
| 
Of 2 brothers/sisters who went shopping for clothes...(that the best analogy I 
could think of, but it does give me a bad name)  :-)
| 
| >The only premise is that the application and the ASE 
| supplying the remote 
| >operation concept must be the same.  This is not always 
| the case: The rest of 
| >the world has standaized itself on a ITU SS7 stack with 
| ITU or ETSI defined 
| >applications(called sometimes CCS7 for Common channel 
| signalling nr 7). The US 
| >and Canada are using a ANSI SS7 stack with ANSI defined 
| applications. The good 
| >news is that up to and including the network layer, the 
| functionalty and 
| >syntax of the message is the same. The bad new is that 
| the application layer 
| >And what is worse internetworking between the US and the 
| Rest of world 
| >is not considered usefull at this moment.(turning the US 
| into a SS7 island) To 
| >a European used to crossing networks borders at will  in 
| the SS7 networks, 
| >this is nearly impossible to believe.
| 
| 
| Actually I find this quite easy to believe !
| 
| 
| >If everbody has a universal number, then everybody has a 
| database entry 
| >somewhere in a node somewhere in the world. To obtain 
| number portability, a 
| >commonly owned database can be used(distributed of course 
| over a number of 
| >nodes) or a redirection to the second operator  in the 
| database of the first 
| >operator could be installed. 
| >
| >As for the number of entries in a database, in a GSM or 
| IS-41 net, a HLR can 
| >contain more than 200 000 entries, and most of these 
| people willl be moving, 
| >so the location update alone will be generating most 
| traffic. So short 
| >transaction over a connectioless network are indeed used, 
| even in a telephone 
| >system.
| >
| 
| 
| Hmm... makes doing ATMARP for 10000 hosts seem quite tame 
| by comparison.
| Now maybe if we could just get the Americans and the 
| Europeans to insist on
| different packet formats or something it might be a bit 
| more challenging :-)

And risk a number of collective suicides? Arhggg  :-)

There is still some hope. The US PCN networks who are using GSM, should have 
the most easy way of interworking interworking with the Row(Rest of world), 
because only the transaction/remote operations part of the message is 
different: ANSI versus ITU TCAP(transaction capability application part= 
connectionless little,leaner(not meaner!) sister of ROSE of ACSE). 


| 
| Bryan Gleeson,
| Adaptec.
| 

Yours sincerly,
Lode Coene

Siemens  ATEA
SW lab applied research & protocols - CCS7 software II      tel: 
+32-14-25-2081
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            fax: +32-14-25-3025
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