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

[Gustavo Marsico]

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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