Subject: Different between M2PA and TALI?

From: Patrick Lam <[email-masked]>
Date: Tue, 04 Dec 2001 15:09:14 -0800

Hi:

Can someone give me a simple pros/cons between M2PA and TALI?  I am
assuming we can compare them because both of them are layer 4.  Is this
assumption correct?

Also, since M2PA runs on SCTP, and TALI runs on TCP, at first sight M2PA
seems to be a better choice when reliability is preferred.  But why some
sompanies are still using TALI?  Simply because they need support from
Tekelec?  Am I missing something about TALI here?

Thanks very much in advance,

Patrick.

---
You are currently subscribed to sigtran as: [email-masked]
To unsubscribe send a blank email to [email-masked]

---

From: Jacques Rajchgod <[email-masked]>
Date: Wed, 05 Dec 2001 09:41:19 -0600

M2PA is a L2 protocol, not a L4 one. See M2PA section 1.5 - the diagrams. L4
are the users: ISUP, SCCP, TUP, B-ISUP, etc...

Jacques Rajchgod
MCI Worldcom
Next Generation System Evaluation
Tel: [972] 729-7180
E-mail: [email-masked]

> -----Original Message-----
> From: Patrick Lam [mailto:[email-masked]]
> Sent: Tuesday, December 04, 2001 5:09 PM
> To: sigtran
> Subject: Different between M2PA and TALI?
>
>
> Hi:
>
> You are currently subscribed to sigtran as: [email-masked]
> To unsubscribe send a blank email to
> [email-masked]
>

---

---

From: Mark Davidson <[email-masked]>
Date: Fri, 7 Dec 2001 09:42:45 -0500

>Thanks very much in advance,

TALI is very similar to M3UA, not M2PA.  TALI and M3UA are
intended to provide an adaptation layer between SS7 and IP.
As such, both have support for MSU encapsulation, SNM messages,
routing key registration, etc.  Both require a transport
layer.  Although TALI uses TCP, there is no reason why it
could not use SCTP (SCTP Payload Protocol Id 9 = TALI).
SCTP did not exist at the time TALI was first implemented
and was therefore not originally an option.

Some features of TALI (* also in M3UA):
    1. *MSU encapsulation
    2. supports normalized ISUP
    3. *supports multiple ITU national networks over single connection
    4. *routing key registration
    5. reference implementation available
    6. RFC available (3094)

The principle advantage of TALI at this point is simply
that it is available, and has been in use, carrying
live traffic, for several years.  The pervasiveness of TCP
makes TALI easier to implement since you don't need to
implement or port SCTP in addition.

Whether SCTP is more reliable than TCP remains to be seen.
In theory the support for multi-homing could make SCTP
more reliable.  What we have seen in practice with TALI/TCP
is that incorrectly configured IP networks resulting in
large round-trip times and packet loss, coupled with
retransmission algorithms that are designed with
congestion avoidance in mind cause most of the field
problems.  Many of the problems we've seen would also
happen in SCTP due to its similar retransmission algorithms.

The tradeoff for providing multi-homing and multiple
stream support in SCTP is higher overhead both in terms
of bandwidth and in CPU utilization.  Our experience has
shown M3UA/SCTP implementations with no bundling are
approximately 30% slower than TALI/TCP implementations
with the Nagle algorithm disabled.

The TALI technical specification and reference implementation
have been available since December, 1999 at
http://www.tekelec.com/tali

Mark Davidson
[email-masked]

---