RE: RFC 4666 on Signaling System 7(SS7)Message TransferPart 3 (MTP3) - User Adaptation Layer (M3UA)

Tolga -

1) We have no control over what a customer or other vendor decides to
do.

2) I'm not sure how you define the "main principles of SIGTRAN
protocols".

3) I don't believe that this is equivalent to putting an entire linkset
on one line card.  I'm just talking about putting one multihomed
association on one NIC card with SCTP running on that NIC.  I still have
multiple NICs.

4) This is happening in the real world and message loss is occurring.  I
would be great if the SIGTRAN community worked together to find a real
solution rather than hoping that people will always implement the
perfect solution in the perfect network.

Regards,
Lincoln 

-----Original Message-----
From: Tolga Asveren [mailto:[email protected]] 
Sent: Thursday, September 21, 2006 9:58 AM
To: Haresign Lincoln
Cc: [email protected]
Subject: RE: [Sigtran] RFC 4666 on Signaling System 7(SS7)Message
TransferPart 3 (MTP3) - User Adaptation Layer (M3UA)

Lincoln,

The SCTP implementation you mentioned is of course possible, but
considering the role of SCTP and its multihoming capability in SIGTRAN,
I wouldn't use such a SCTP card for my deployment, because the rationale
behind using SCTP for SIGTRAN is to provide network interface/network
reliability.

BTW, for the equivalent of this in SS7, what would happen if I use a
single card with 16 links? Isn't it the same problem, if the card dies,
I loose everything.

The reason I am against the mechanism is because it is againt the main
principles of SIGTRAN protocols and I don't think there is a real
problem (but this of course is just my personal opinion). To me, the
correct aproach is to make people aware how M3UA addresses network
interface/network/host redundancy and let them engineer their IP
networks properly.

    Thanks,
    Tolga

> -----Original Message-----
> From: Haresign Lincoln [mailto:[email protected]]
> Sent: Thursday, September 21, 2006 9:42 AM
> To: Tolga Asveren; [email protected]
> Cc: [email protected]
> Subject: RE: [Sigtran] RFC 4666 on Signaling System 7(SS7)Message 
> TransferPart 3 (MTP3) - User Adaptation Layer (M3UA)
>
>
> Tolga,
>
> It would be possible to implement SCTP in an embedded on a NIC card 
> with dual ports for supporting multihoming and the UA layers running 
> on the host.  If the NIC card failed (OR if a Tier 4 support 
> engineering accidently unplugged a few power cables disabled a couple 
> routers), we could loose some associations while still keeping others.
>
> Some type of "OPTIONAL" retrieval mechanism would go towards the 0% 
> message loss that SS7 is striving towards.  I'm not sure why you would

> oppose such a mechanism if it is optional.
>
> Regards,
> Lincoln
>
> -----Original Message-----
> From: Tolga Asveren [mailto:[email protected]]
> Sent: Thursday, September 21, 2006 9:33 AM
> To: [email protected]
> Cc: [email protected]
> Subject: RE: [Sigtran] RFC 4666 on Signaling System 7(SS7)Message 
> TransferPart 3 (MTP3) - User Adaptation Layer (M3UA)
>
> Satya,
>
> If SCTP association to ASP11 is lost, this implies that ASP11 host is 
> down, because network redundancy is provided with SCTP multihoming and

> proper IP network engineering. When ASP11 is down, there is no way to 
> retrieve anyhting. The possibility of loosing SCTP association without

> a host failure should be guranateed to be below some acceptable 
> threshold value, i.e.
> really really low.
>
> BTW, your assumption of SCTP not being able to failover between paths 
> with no message loss is not correct. SCTP does this without message 
> loss and missequencing.
>
>      Thanks,
>      Tolga
> -----Original Message-----
> From: Satya Prasad Nemana
> [mailto:[email protected]]
> Sent: Thursday, September 21, 2006 9:27 AM
> To: Tolga Asveren
> Cc: [email protected]
> Subject: Re: [Sigtran] RFC 4666 on Signaling System 7 (SS7)Message 
> TransferPart 3 (MTP3) - User Adaptation Layer (M3UA)
>
>
> Tolga,
>
> Consider the situation
>
> SP1 is routing  ISUP messages to  AS1 (which has ASP11, ASP12) via SG-
> SG1 in loadshared...
> SG1 has sent 1000 msgs to AS1 via SCTP assoc of ASP11..
> When SCTP assoc of ASP11 fails and AS1 has acked via SACK 940 msgs..
> The current implementations do not have the capacity to retransmit the

> remaining 60 msgs...
> They are lost although we have ASP12 for redundancy purposes.
>
> Considering the case of Multi Homing also...
> even if ASP11 is multi homed and loses one path with a similar 
> situation, there is still no chance of retransmitting the msgs as M3UA

> does not define any such method for retrieval ....
>
> Regards,
> Satya Prasad
>
>
>
> Tolga Asveren wrote:
>
> Satya,
>
> In M3UA network redundancy is provided by SCTP multihoming and host 
> redundancy by using multiple ASPs for an AS.
>
> For the configuration you are mentioning, if the ASP host is down, 
> there is no message retrieval possible in SS7 as well for the similar 
> case. If the SCTP association is lost to an ASP, this shouldn't happen

> due to network problems (this property be guaranteed with SCTP 
> multihoming and proper IP network configuration) and should indicate a
host failure.
>
>      Thanks,
>      Tolga
>
>
> -----Original Message-----
> From: Satya Prasad Nemana
> [mailto:[email protected]]
> Sent: Thursday, September 21, 2006 5:05 AM
> To: [email protected]
> Cc: [email protected]; [email protected]; [email protected]
> Subject: Re: [Sigtran] RFC 4666 on Signaling System 7 (SS7) Message 
> TransferPart 3 (MTP3) - User Adaptation Layer (M3UA)
>
>
>
> A general comment on ASP failover cases, M3UA does not have any method

> of doing retrieval /retranamission Although SCTP does have the 
> capability through multi homing, the ULP should have the request in 
> place to do the retrieval/retransmission In the case of a single AS 
> having only a single ASP configured, there is no chance of retrieval 
> (but this is the most rare configuration as networks are configured  
> not to go down with a single point of failure) In case the AS is 
> configured with two ASPs and each having a different SCTP assoc with a

> single path in  each of the assoc..
> there is no chance of message retrieval... as per the current rfc.
>
> No idea if this was not felt important in a telecom network!!
>
> [email protected] wrote:
>
>
> A new Request for Comments is now available in online RFC libraries.
>
>
>        RFC 4666
>
>        Title:      Signaling System 7 (SS7) Message
>                    Transfer Part 3 (MTP3) - User
>                    Adaptation Layer (M3UA)
>        Author:     K. Morneault, Ed.,
>                    J. Pastor-Balbas, Ed.
>        Status:     Standards Track
>        Date:       September 2006
>        Mailbox:    [email protected],
>                    [email protected]
>        Pages:      124
>        Characters: 292991
>        Obsoletes:  RFC3332
>        See-Also:
>
>        I-D Tag:    draft-ietf-sigtran-rfc3332bis-06.txt
>
>        URL:        http://www.rfc-editor.org/rfc/rfc4666.txt
>
> This memo defines a protocol for supporting the transport of any SS7 
> MTP3-User signalling (e.g., ISUP and SCCP messages) over IP using the 
> services of the Stream Control Transmission Protocol.  Also, provision

> is made for protocol elements that enable a seamless operation of the 
> MTP3-User peers in the SS7 and IP domains.  This protocol would be 
> used between a Signalling Gateway (SG) and a Media Gateway Controller 
> (MGC) or IP-resident Database, or between two IP-based applications.  
> It is assumed that the SG receives SS7 signalling over a standard SS7 
> interface using the SS7 Message Transfer Part (MTP) to provide 
> transport.  This document obsoletes RFC 3332.  [STANDARDS TRACK]
>
> This document is a product of the Signaling Transport Working Group of

> the IETF.
>
> This is now a Proposed Standard Protocol.
>
> STANDARDS TRACK: This document specifies an Internet standards track 
> protocol for the Internet community,and requests discussion and 
> suggestions for improvements.Please refer to the current edition of 
> the Internet Official Protocol Standards (STD 1) for the 
> standardization state and status of this protocol.  Distribution of 
> this memo is unlimited.
>
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>
> Joyce K. Reynolds and Sandy Ginoza
> USC/Information Sciences Institute
>
> ...
>
>
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