Does Energy Savings Mode Exist With BRI/PtP ?

Home » Asterisk Users » Does Energy Savings Mode Exist With BRI/PtP ?
Asterisk Users 10 Comments

Hello,

I always thought that Energy Savings mode existed with ISDN Basic Rate Interface in Point -to-multi-Point but it didn’t with Point-to-point.

Is this correct ?
Have you ever met a public PSTN switch configured to “cut” B ISDN channels in Point-to-point.signalling ?

Regards.

10 thoughts on - Does Energy Savings Mode Exist With BRI/PtP ?

  • Yes, I can confirm that. P2P always requires a PBX and you can easily build up trunks of P2P
    connections. So all channels always need to work in a coordinated way, if you allow this sloppy formulation. Another reason for not allowing the energy saving mode is probably that in some countries part of the phone number resolution has to happen inside the pbx on the customer side. This could be a problem if it takes too much time to wake up a device, or if the state of the connection cannot be determined beforehand.

    P2MP does have an energy saving mode which depends on the PSTN and on the TE device. Sometimes phone companies allow special sequences (like *121#) that explicitly allow to disable the energy saving mode, if the P2MP connection is connected up to a PBX. Some customer devices have configuration options like “connect to a pbx” which send exactly this sequence to the next telephone switch.

    All the technicals docs are available online, but I have yet to find a person, myself included, who actually read them all. All of this applies to Western Europe, only.

  • 2013/12/11 jg

    So if my understanding is correct, Energy Saving mode exists in P2P BRI
    lines. How do you monitor these lines ?
    By monitoring, I mean “getting an SNMP trap when the line is going down”, for instance. Maybe I should just convince myself that I should not check anymore line status looking a flag updated in real time, but simply trying to send an outgoing call as I would with analog lines.

    Have you also heard about this special sequence with P2P lines or is it something especially for P2MP ?

    Yes that’s true.

  • No, not for P2P lines, only for P2MP lines.

    Most of the time I use a vendor specific utility, but “pri show spans” gets the status as well.

    The sequence I gave is for P2MP only, but I don’t know which telcos are using it (except for mine). P2P never sleeps as said before.

    I haven’t checked what happens when a P2P connection is not connected to anything at all. Theoretically it could go into the energy saving mode, but once it is connected, then it doesn’t.

    jg

  • 2013/12/11 jg

    At the moment, I’m having trouble with lines going up and down all day long. I asked them to be created as P2P. Mostly but not always calls are passing in and out correctly.

    So, if I’m not mistaken, either :
    – these lines are configured as P2MP (and not as P2P as required),
    – I’m facing something else I’ve never met before.

    As these lines are up most of the time, I’m having a hard time to get any useful help by Telco beside “level 1” basic checks.

    For the record, these lines are terminated on my side with a Patton smartnode (most of the time, I use Digium BRI boards). During off hours, I’ll try to check what happens when toggling to P2MP mode.

  • I doubt that the energy-saving is causing the trouble. How do you get the ISDN-signal? Is it an S0-bus? If yes, I may be able to be of further help. Even if the connection goes down, it should not matter for P2MP connections. But S0-bus problems can be nasty (though seen rarely these days). I would bet on the 2nd choice. I doubt that you do get anything useful if you pick the wrong mode.

    Are you sure that your are not dealing with termination issues? Try sending a T.30 fax with fine resolution and ecm enabled when your connection is up. If it takes too long or fails, this is something to look at.

    jg

  • 2013/12/11 jg

    I’m not 100% sure I’m correctly understanding these latter two questions.

    Anyway, refering to http://en.wikipedia.org/wiki/Integrated_Services_Digital_Network / Basic rate Interface paragraph, my setup includes :
    – a single network termination unit, installed and managed by telco, is connected to public network through 2 twisted pairs,
    – this unit includes two small electronic cards,
    – each card has two RJ45 sockets,
    – each card is connected through a single Cat5 straight, 1m long patch cord to a single BRI port from my Patton box,
    – both Patton’s BRI ports are managed as a “hunt group” (for outbound calls),
    – for inbound, I didn’t checked but usually, Telco sends one call on one interface, the next one and the next interface.

    So to summarize, (I think):
    – I’m getting ISDN signal from two distinct copper pairs,
    – it is not an S0-bus.

    You mean: layer1 is down but layer3 remains up ?
    I’m seeing layer3 going down for 4 or 5 seconds, then up again. This happens for both interfaces.

    From memory, with a misconfiguration between P2P and P2MP, you get no call at all which is not the case.

    Try sending a T.30 fax with fine resolution and ecm enabled when your

    Can you elaborate a bit ?
    I’m using an old Asterisk 1.6.1 version there so I can’t rely on T.38/T.30
    gateway feature at the moment.

  • I double-checked with other locations (also using Patton devices and I
    didn’t get any complain). I can find the same pattern everywhere:

    2013-12-11T20:17:39 : LOGINFO : Link down on interface bri 0 0 0
    2013-12-11T20:17:39 : LOGINFO : Link down on interface ISDN 0 0
    2013-12-11T20:18:11 : LOGINFO : Link up on interface bri 0 0 0
    2013-12-11T20:18:11 : LOGINFO : Link up on interface ISDN 0 0
    2013-12-11T20:18:14 : LOGINFO : Link down on interface bri 0 0 0
    2013-12-11T20:18:15 : LOGINFO : Link down on interface ISDN 0 0
    2013-12-11T20:18:18 : LOGINFO : Link up on interface bri 0 0 0
    2013-12-11T20:18:18 : LOGINFO : Link up on interface ISDN 0 0
    2013-12-11T20:21:14 : LOGINFO : Link down on interface bri 0 0 1
    2013-12-11T20:21:15 : LOGINFO : Link down on interface ISDN 0 1
    2013-12-11T20:21:46 : LOGINFO : Link up on interface bri 0 0 1
    2013-12-11T20:21:46 : LOGINFO : Link up on interface ISDN 0 1
    2013-12-11T20:21:49 : LOGINFO : Link down on interface bri 0 0 1
    2013-12-11T20:21:49 : LOGINFO : Link down on interface ISDN 0 1
    2013-12-11T20:21:53 : LOGINFO : Link up on interface bri 0 0 1
    2013-12-11T20:21:53 : LOGINFO : Link up on interface ISDN 0 1
    2013-12-11T20:37:39 : LOGINFO : Link down on interface bri 0 0 0
    2013-12-11T20:37:39 : LOGINFO : Link down on interface ISDN 0 0
    2013-12-11T20:38:11 : LOGINFO : Link up on interface bri 0 0 0
    2013-12-11T20:38:11 : LOGINFO : Link up on interface ISDN 0 0
    2013-12-11T20:38:13 : LOGINFO : Link down on interface bri 0 0 0
    2013-12-11T20:38:13 : LOGINFO : Link down on interface ISDN 0 0
    2013-12-11T20:38:13 : LOGINFO : Link up on interface bri 0 0 0
    2013-12-11T20:38:14 : LOGINFO : Link up on interface ISDN 0 0
    2013-12-11T20:41:14 : LOGINFO : Link down on interface bri 0 0 1
    2013-12-11T20:41:14 : LOGINFO : Link down on interface ISDN 0 1
    2013-12-11T20:41:46 : LOGINFO : Link up on interface bri 0 0 1
    2013-12-11T20:41:46 : LOGINFO : Link up on interface ISDN 0 1
    2013-12-11T20:41:49 : LOGINFO : Link down on interface bri 0 0 1
    2013-12-11T20:41:49 : LOGINFO : Link down on interface ISDN 0 1
    2013-12-11T20:41:53 : LOGINFO : Link up on interface bri 0 0 1
    2013-12-11T20:41:53 : LOGINFO : Link up on interface ISDN 0 1

    So it seems common from Telco to turn ISDN lines going down and up, once in while and this is not for energy savings.

    2013/12/11 jg

  • 2013/12/12 jg

    My telco is Orange in France.

    Yes of course, I was referring to T.38 and completly forgot about pure G711
    faxing with Asterisk sending T.30 fax to the Patton gateway,through SendFAX
    application. Please, apologize for forgetting this.

    I’ll try to to send a 10-pages long fax and report here my findings.

  • 2 pages are enough to see whether there are any problems.

    As far as P2MP signaling is concerned, you can hook up to 8 devices (64 < = TEI < 127) to such a PSTN connection. To simplify installations, there is usually a bus topology, but proper termination can be problem (in rare cases). I am not familiar with the details and terminology in France, but have a look at little box in http://de.wikipedia.org/wiki/Network_Termination_for_ISDN_Basic_rate_Access. If this looks familiar, you do have an S0 bus.

    If you do have an S0 bus and a P2MP connection, then it is somewhat easier to dissect the problem.

    jg