cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
Highlighted
New Contributor III

TA908e Random B-channel Restarts

Jump to solution

I am testing the TA908E connected to a Cisco UC540 PBX for SIP-PRI and I have noticed that occasionally when there are not active calls - the IAD is sending B-channel restarts for every channel in the PRI. I am trying to time it and see if it happens every hour as a "refresh" or "keepalive" or if there is actually an interoperability issue between the two devices. I'm not seeing slips, code violations etc.

Show commands below and snippet of PRI config.

#SHOW COMMANDS

TA908e#sh int pri 3

pri 3 is UP

  Switch protocol:  National ISDN 2

  Signaling role:  network (NT) b-channel-restarts enabled

  b-channel-restarts:  enabled

  Calling-party override:  disabled

  Calling-party presentation:  allowed

  Calling-party screening:  auto

  Calling-party number:  (no number configured)

  Digits transferred all

  Name-delivery:  via Setup msg / Facility IE

  Progress indicator #8 in alerting message:  enabled

  Progress indicator #2 in connect message:  disabled

  Progress indicator #1 in setup message:  disabled

  Progress indicator #3 in setup message:  disabled

  Progress indicator location:  public

  resource-selection: linear descending

  TBCT:  enabled

  area code: 

  Transmission of redirecting numbers is enabled

  Redirecting numbers: sent as received

  Connected interface: t1 0/3 tdm-group 1

  Channel status 123456789012345678901234

                 .......................D

    Legend: - = Unallocated        . = Inactive

            A = Active B channel   B = Backup D channel

            D = Active D channel   M = Maintenance

            R = Restart

  Last clearing of "show interface" counters: never

    36235 packets input, 173906 bytes, 0 no buffer

    0 runts, 0 giants, 0 throttles

    1 input errors, 0 CRC, 0 frame

    1 abort, 0 discards, 0 overruns

    36215 packets output, 173885 bytes, 0 underruns

TA908e#

TA908e#

TA908e#sh int t1 0/3

t1 0/3 is UP

  Receiver has no alarms

  T1 coding is B8ZS, framing is ESF

  Clock source is system, FDL type is disabled

  Line build-out is 0dB

  No remote loopbacks, No network loopbacks

  Acceptance of remote loopback requests enabled

  Tx Alarm Enable: rai

  Last clearing of counters 3d 19:18:18

    loss of frame  : 1, last occurred 01:56:15

    loss of signal : 1, last occurred 01:56:15

    AIS alarm      : 0

    Remote alarm   : 0

  DS0 Status: 123456789012345678901234

              XXXXXXXXXXXXXXXXXXXXXXXX

  Status Legend: '-' = DS0 is not allocated

                 'X' = DS0 is allocated (nailed)

  Signaling Bit Status: 123456789012345678901234

                   RxA: 000000000000000000000000

                   RxB: 000000000000000000000000

                   TxA: 000000000000000000000000

                   TxB: 000000000000000000000000

                        123456789012345678901234

  Line Status: -- No Alarms --

  5 minute input rate 0 bits/sec, 0 packets/sec

  5 minute output rate 0 bits/sec, 0 packets/sec

  Current Performance Statistics:

    0 Errored Seconds, 0 Bursty Errored Seconds

    0 Severely Errored Seconds, 0 Severely Errored Frame Seconds

    0 Unavailable Seconds, 0 Path Code Violations

    0 Line Code Violations, 0 Controlled Slip Seconds

    0 Line Errored Seconds, 0 Degraded Minutes

  TDM group 1, line protocol is not set

    Encapsulation is not set

#PRI CONFIG

! ADTRAN, Inc. OS version R11.10.1.E

! Boot ROM version R10.9.3.B2

! Platform: Total Access 908e (3rd Gen), part number 4243908F2

! Serial number CFG1444961

!

interface t1 0/3

  fdl none

  tdm-group 1 timeslots 1-24 speed 64

  no shutdown

!

interface t1 0/4

  shutdown

!

!

interface pri 3

  role network b-channel-restarts enable

  isdn name-delivery setup

  connect t1 0/3 tdm-group 1

  isdn supplementary-service tbct

  no shutdown

!

!

isdn-group 1

  min-channels 1

  max-channels 12

  connect pri 3

!

voice codec-list USERS

  default

  codec g711ulaw

!

!

voice trunk T02 type isdn

  description "PRI to PBX"

  resource-selection linear descending

  connect isdn-group 1

  no early-cut-through

  modem-passthrough

  rtp delay-mode adaptive

  codec-list USERS

!

!

voice grouped-trunk "PRI TRUNK GROUP"

  trunk T02

  accept $ cost 0

!

Labels (2)
Tags (2)
0 Kudos
1 Solution

Accepted Solutions
Highlighted
New Contributor III

Re: TA908e Random B-channel Restarts

Jump to solution

I understand that the command is in place actually making it restart b-channels I was looking more for why b-channel-restarts would be needed at all every 60 minutes. I received the answer from support.

B channel restarts is an ISDN spec. If it is enabled, we will send a restart message every hour for inactive B channels. It requires that the device receiving the restart , send an ACK to the restart. If it does not the ISDN spec calls for that B channel to be locked out.

The advantage of restart messages is that it helps prevent B channel lock out conditions. Either side of the PRI can send them.

The disadvantages of restarts are, that in a high call volume environment , you have a short period where calls can't be made or received. Also it is possible that a PBX does not support

restart messaging because, either 1 it is not configured or 2 the firmware is out of date on the PBX.

View solution in original post

0 Kudos
2 Replies
Valued Contributor
Valued Contributor

Re: TA908e Random B-channel Restarts

Jump to solution

George, it appears you have b-channel restarts enabled:

interface pri 3

  role network b-channel-restarts enable

If you want them disabled, just change that command to "role network".

Thanks

Jay

Highlighted
New Contributor III

Re: TA908e Random B-channel Restarts

Jump to solution

I understand that the command is in place actually making it restart b-channels I was looking more for why b-channel-restarts would be needed at all every 60 minutes. I received the answer from support.

B channel restarts is an ISDN spec. If it is enabled, we will send a restart message every hour for inactive B channels. It requires that the device receiving the restart , send an ACK to the restart. If it does not the ISDN spec calls for that B channel to be locked out.

The advantage of restart messages is that it helps prevent B channel lock out conditions. Either side of the PRI can send them.

The disadvantages of restarts are, that in a high call volume environment , you have a short period where calls can't be made or received. Also it is possible that a PBX does not support

restart messaging because, either 1 it is not configured or 2 the firmware is out of date on the PBX.

View solution in original post

0 Kudos