[asterisk-ss7] At what interval should FISUs be sent?

[Robert Kenton]

Well, according to Q.706 (SS7 Message Transfer Part Signalling Performance),
the emission time is 0,75 ms.
I think this is the interval of sending each FISU message because as in the
Q703 state that "Under normal conditions, when no message signal units are
to be transmitted or retransmitted, fill-in signal units are sent
continuously"

Robert.

On Sat, Jul 4, 2009 at 12:32 AM, Gustavo Marsico
<gustavomarsico at gmail.com>wrote:

> Yes, a few switches acts in that way, but it's very uncommon. As I
> tested a few years ago, EWSD in V11 (V13 and V15 works good) and 5ESS
> V14 can fail with that behavior.
>
> Regards,
>
> Gustavo
>
>
> On Jul 3, 2009, at 8:27 PM, Marcelo Pacheco wrote:
>
> > I've seen one certified switch for Brazilian ISUP/SS7 (MTP is
> > identical
> > to ITU-T) the switch is from Digitro that delivers FISUs only 25% of
> > link idle time, 75% of idle octets (considering FISUs idle octets) are
> > flags. That switch talked with sucess with Ericsson AXE, Nortel DMS,
> > Vectura (operating as an STP), Tropico RA and some others, without
> > link
> > instability.
> >
> > Anyhow, libss7 using dahdi mtp2 shouldn't suffer from this issue, as
> > well as chan_ss7, as both generate FISUs not stop correctly.
> >
> > Regards,
> >
> > Marcelo Pacheco
> >
> > Kristian Nielsen wrote:
> >> "Gustavo Marsico [Gmail]" <gustavomarsico at gmail.com> writes:
> >>
> >>
> >>> It's talking about Japan:
> >>>
> >>> Note: In the ITU-T Japan variant, signaling link quality is
> >>> checked by the
> >>> continuous transmission of flag octets (8-bit bytes) rather than
> >>> FISUs;
> >>> FISUs are sent only at predefined timer intervals (e.g., once
> >>> every 150
> >>> milliseconds).
> >>>
> >>> If you live in Japan can make sense that, but in ITU world it's
> >>> just like as
> >>> Kristian's said.
> >>>
> >>
> >> Yes, I meant ITU SS7. Forgot about the multiple variants ...
> >>
> >> Here is the relevant quote from ITU Q.703:
> >>
> >> 11.2.2 For the basic error control method, the priorities are:
> >> Highest    1. Link status signal units.
> >>           2. Message signal units which have not yet been
> >> acknowledged and for which a
> >>               negative acknowledgement has been received.
> >>           3. New message signal units.
> >>           4. Fill-in signal units.
> >> Lowest     5. Flags.
> >>
> >> So fill-in signal units are sent unless some serious error prevents
> >> sending
> >> anything but flags.
> >>
> >> Don't know about any other variants of SS7.
> >>
> >> - Kristian.
> >>
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