Re: M3UA and SUA recommendations
Stanislav Ivanovich <[email protected]>
| Newsgroups | gmane.ietf.sigtran |
|---|---|
| Message-ID | <[email protected]> |
Siu Chai, See my comments below. / Stanislav Siu Chai Tho <[email protected]> wrote: Hello Stainislav, Stanislav Ivanovich <[email protected]> wrote: [Stanislav Ivanovich] The specifications do much more than that. They essentialy define a concept of application redundacy which is controlled by ASP SM/TM messages. [Siu Chai Tho] I not understand this. Isn't it just signalling transport redundancy that is managed and it is an option for applications to use it for application redundancy or not ? RFC 2719 does not mention anything on SIG-user redundancy. [Stanislav Ivanovich] Certainly not! What do you think the AS ("Application Server") concept is about? Do you think that Application Server served by several ASP'es is for the sake of transmission redundancy??? Of course not! However it is true what you said that it is optinal to use. Where did I say that it was mandatory??? I did not say that! No one forces you that you must have several ASP/IPSP'es in one AS. You can have just one application process instance in each AS thus having no application redundancy. However this does not change anything about the point -> AS concept certainly is the concept of application redundancy where several application processes serve the same application (so if one fails the application survives). That is the point. If you do not need this then you do not use it. Transmission redundcy is addrssed by lower layer protocols and functions (SCTP, IP, Ethernet...). Of course SGP is relay process (not application one) so multiple SGP'es in one SGW is example of transmission related redundancy. Note however that SGP'es are not part of any AS (i.e. SGP'es do not send ASP SM/TM messages). [Stanislav Ivanovich] What specifications do tell you is how should signalling processes behave on the external protocol and what is the functionality the prcesses should contain. Internal structure of signalling processes is irrelevant for specifications. [Siu Chai Tho]I feel that you have misunderstood my question. I was trying to reassure that there are boundaries of a layer defined as mentioned in chapter 1.6 of RFC 3868 and also in chapter 3.1 RFC 2719. I understand that implementations can do whatever they like and are not forced to use layers. However, what is the purpose of using the word layer when there is no layer intended ? [Stanislav Ivanovich] I did understand you! However see my last mail sent to you with some references and points. [Stanislav Ivanovich] No! ASP and IPSP are processes which contain user functions what is not the case for SGP. For example SGP-ASP protocol is designed to model communication between MTP3 and MTP3-user function for M3UA or SCCP and SCCP-user function for SUA. So ASP is container into which you load your user function. The essentce of the AS concepts (which make 80% of specifications for both M3UA and SUA) is that it supports application redundancy by means of ASP SM/TM messages. [Siu Chai Tho] ASP and IPSP contains user functions but SGP doesn't ? Isn't it just that any signalling process is just a communication endpoint for SUA/M3UA ? The user functions at the ASP or SCCP/MTP functions at the SGP reside in their own components or am I mistaken here ? [Stanislav Ivanovich] Why then different process types??? Read terminology sections of both SUA and M3UA: "IP Server Process (IPSP) - A process instance of an IP-based application. An IPSP is essentially the same as an ASP, except that it uses SUA in a peer-to-peer fashion." "Signalling Gateway Process (SGP) - A process instance of a Signalling Gateway. It serves as an active, load-sharing or broadcast process of a Signalling Gateway." [Stanislav Ivanovich] Application granularity (ie. AS representation in SS7 language) is implementation choice thus not subject to specifications. But the specifications allow you to define your applications very flexibly (e.g. ISUP + BICC for DPC=2-100 shall be 1 AS). [Siu Chai Tho] I was trying to ask if it is possible to map one MTP/SCCP-SAP (or AS) into multiple ASPs (inside the same node). If this is an implementation option as you indicate I'm happy with the answer. [Stanislav Ivanovich] SS7 addresses are external representation of an application (Application Server). If your local application (AS) is supported by several application processes (instances) then you use several ASP'es. If not then you use just one ASP. 6) Is the recommendation of a layered implementation seen as a benefit or best current practice ? [Stanislav Ivanovich] Again. This is implementation. You cannot answer thuis queston by looking into xxUA specifications but instead by looking into your current SS7 implementation product descriptions, sequence diagrams etc... [Siu Chai Tho]I have again the feeling that you understood me wrong. I was asking for a reasoning of the layer recommendation inside the RFCs. How do others implement it ? [Stanislav Ivanovich] I did understand you well. Please see my previous answers and refferences. Thank you, Joe Send instant messages to your online friends http://au.messenger.yahoo.com --------------------------------- Yahoo! Photos Ring in the New Year with Photo Calendars. Add photos, events, holidays, whatever. _______________________________________________ Sigtran mailing list [email protected] https://www1.ietf.org/mailman/listinfo/sigtran