Thursday 9 August 2012

PRI/E1 Configuration on Cisco Voice Gateway


 Step by step configuration of PRI/E1 on Cisco Voice Gateway
The Primary Rate Interface (PRI) is a standardized telecommunications service level within the Integrated Services Digital Network (ISDN) specification for carrying multiple DS0 voice and data Transmission. E1 is a European Standard and has 32 x 64Kbps channels where 30 is used for voice and two are used for synchronization and signaling

ISDN PRI Switch types:
Below is the list of ISDN PRI switch type support on Cisco voice gateways

 primary-4ess    Lucent 4ESS switch type for the U.S.
 primary-5ess    Lucent 5ESS switch type for the U.S.
 primary-dms100  Northern Telecom DMS-100 switch type for the U.S.
 primary-dpnss   DPNSS switch type for Europe
 primary-net5    NET5 switch type for UK, Europe, Asia and Australia
 primary-ni      National ISDN Switch type for the U.S.
 primary-ni2c    The Cisco NAS-SC switchtype based on NI2C
 primary-qsig    QSIG switch type
 primary-ts014   TS014 switch type for Australia (obsolete)

1. Configuration

Note: once you logged-in in the router you will see card type command required in show running output


Card type e1 0 0
!
network-clock-participate wic 0
network-clock-select 1 E1 0/0/0
!
isdn switch-type primary-net5
 
!
controller E1 0/0/0
 framing no-crc4
 linecode hdb3
 pri-group timeslots 1-31
!
voice-port 0/0:15
 
!
dial-peer voice 1 pots
Incoming called-number.
 direct-inward-dial
port 0/0/0:15
!
2. Verification

Now we have to check the status of PRI using show isdn status command. If you see the layer 2 state as MULTIPLE_FRAME_ESTABLISHED this means that PRI is successfully configured and ready to make/receiveCalls. If it doesn’t show the MULTIPLE_FRAME_ESTABLISHED then follow the troubleshooting section.

VOICE_GW#show isdn status
Global ISDN Switchtype = primary-net5
ISDN Serial0/0/0:15 interface
        dsl 0, interface ISDN Switchtype = primary-net5
    Layer 1 Status:
        ACTIVE
    Layer 2 Status:
        TEI = 0, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED
    Layer 3 Status:
        5 Active Layer 3 Call(s)
    Activated dsl 0 CCBs = 1
        CCB:callid=7D5, sapi=0, ces=0, B-chan=9, calltype=DATA
        
    The Free Channel Mask:  0xFFFF78FC
ISDN Serial0/0/0:15 interface
        dsl 1, interface ISDN Switchtype = primary-net5
    Layer 1 Status:
        ACTIVE
    Layer 2 Status

3.      Troubleshooting

The show isdn status command displays a summary of all ISDN interfaces. It also displays the status of Layers 1, 2, and 3. Complete the following steps to check the status of the layers:

1.       Verify that Layer 1 is in the ACTIVE state. The status of Layer 1 should always be ACTIVE unless the E1 is down.
If the show isdn status command output indicates that Layer 1 is DEACTIVATED, then there is a problem with the physical connectivity of the E1 line. If the line is administratively down, use the no shutdown command to restart the interface.
2.       Ensure that Layer 2 is in the MULTIPLE_FRAME_ESTABLISHED state. This is the desired state for Layer 2, indicating that Layer 2 frames are being exchanged and Layer 2 initialization has finished.
If Layer 2 is not in the MULTIPLE_FRAME_ESTABLISHED state, use the show controller e1 EXEC command to diagnose the problem.
Since the show isdn status command displays a summary of the current status, it is possible that Layer 2 is bouncing up and down despite indicating a MULTIPLE_FRAME_ESTABLISHED state. Use the debug isdn q921 command to verify that Layer 2 is stable.

Following is an example of show isdn status output:
VOICE_GW#show isdn status
Global ISDN Switchtype = primary-net5
ISDN Serial0/0/0:15 interface
        dsl 0, interface ISDN Switchtype = primary-net5
    Layer 1 Status:
        ACTIVE
    Layer 2 Status:
        TEI = 0, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED
    Layer 3 Status:
        5 Active Layer 3 Call(s)
    Activated dsl 0 CCBs = 5
        CCB:callid=7D5, sapi=0, ces=0, B-chan=9, calltype=DATA
        CCB:callid=7D6, sapi=0, ces=0, B-chan=10, calltype=DATA
        CCB:callid=7DA, sapi=0, ces=0, B-chan=11, calltype=DATA
        CCB:callid=7DE, sapi=0, ces=0, B-chan=1, calltype=DATA
        CCB:callid=7DF, sapi=0, ces=0, B-chan=2, calltype=DATA
    The Free Channel Mask:  0xFFFF78FC
 
VOICE_GW#show isdn status
 
ISDN Serial0/0/0:15 interface
        dsl 1, interface ISDN Switchtype = primary-net5
    Layer 1 Status:
        ACTIVE
    Layer 2 Status:
        TEI = 0, Ces = 1, SAPI = 0, State = TEI_ASSIGNED
    Layer 3 Status:
        0 Active Layer 3 Call(s)
    Activated dsl 1 CCBs = 0
    The Free Channel Mask:  0xFFFF7FFF
    Total Allocated ISDN CCBs = 5

Notice that E1 0 (whose D-channel is Serial 0:15) has Layer 1 as ACTIVE and Layer 2 as MULTIPLE_FRAME_ESTABLISHED indicating that the signaling channel is functioning correctly and is exchanging Layer 2 frames with the Telco switch. The D-channel (Serial0/0/0:15) for E1 1 has Layer 1 ACTIVE, but Layer 2 is TEI_ASSIGNED. This indicates that the PRI is not exchanging Layer 2 frames with the switch. Use the show controller e1 x command to troubleshoot.

Using the debug q921 Command
The debug isdn q921 command displays data link layer (Layer 2) access procedures that are occurring at the router on the D-channel.
Note: If debug isdn q921 is turned on and you do not receive any debug outputs, place a call or reset the controller to get debug outputs.
Complete the following steps to ensure that the data link layer access procedures are occurring at the router on the D-channel:
1.       Verify that Layer 2 is stable by looking for messages in the debug output. If the line is bouncing up and down, output similar to the following will appear:

Jul 30 10:06:07.882: %ISDN-6-LAYER2DOWN: Layer 2 for Interface Se0/0/0:15, TEI 0 changed to down
Jul 30 10:06:09.882: %LINK-3-UPDOWN: Interface Serial0/0/0:15, changed state to down
Jul 30 10:06:21.274: %DSX1-6-CLOCK_CHANGE: Controller 0 clock is now selected as clock source
Jul 30 10:06:21.702: %ISDN-6-LAYER2UP: Layer 2 for Interface Se0/0/0:15, TEI 0 changed to up
Jul 30 10:06:22.494: %CONTROLLER-5-UPDOWN: Controller E1 0, changed state to up
Jul 30 10:06:24.494: %LINK-3-UPDOWN: Interface Serial0/0/0:15, changed state to up
 
2.       Verify that only service access point identifier (SAPI) messages appear on both the transmit (TX) and receive (RX) sides. For example:

Jul 30 10:06:52.505: ISDN Se0/0/0:15: TX -> RRf sapi = 0 tei = 0 nr = 0
   Jul 30 10:06:52.505: ISDN Se0/0/0:15: RX <- RRf sapi = 0 tei = 0 NR = 0
Jul 30 10:07:22.505: ISDN Se0/0/0:15: TX -> RRp sapi = 0 tei = 0 NR = 0
Jul 30 10:07:22.509: ISDN Se0/0/0:15: RX <- RRp sapi = 0 tei = 0 NR = 0
Jul 30 10:07:22.509: ISDN Se0/0/0:15: TX -> RRf sapi = 0 tei = 0 NR = 0
Jul 30 10:07:22.509: ISDN Se0/0/0:15: RX <- RRf sapi = 0 tei = 0 NR = 0

3.       Verify that asynchronous balanced mode extended (SABME) messages do not appear. These messages indicate that Layer 2 is trying to reinitialize. The messages usually appear when poll requests (RRp) are transmitted and there is no response from the switch (RRf), or vice versa. Following are examples of SABME messages:
Jul 30 10:06:21.702: ISDN Se0/0/0:15: RX <- SABMEp sapi = 0 tei = 0
Jul 30 10:06:22.494: ISDN Se0/0/0:15: TX -> SABMEp sapi = 0 tei = 0
If SABME messages appear, complete the following steps:

a.        Use the show running-config command to ensure that isdn switch-type and pri-group timeslots are configured correctly. Contact your Service Provider for the correct values and change the isdn switch-type and timeslots respectively
b.       To change the isdn switch-type and pri-group settings, enter the following commands:
c.  VOICE_GW#configure terminal
d.  VOICE_GW(config)#isdn switch-type XXXXXX
e.  VOICE_GW(config)#controller e1 0
f.  VOICE_GW(config-controlle)#pri-group timeslots X-XX
 
4.       Ensure the D-channel is up using the show interfaces serial number:15 command, where the number is the interface number.
If the D-channel is not up, use the no shutdown command to bring it up. For example:
VOICE_GW(config)#interface serial 0/0/0:15
VOICE_GW(config-if)#no shutdown


Note: Dial plan will be cover in next H.323 gateway configuration blog J
 
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3 comments:

  1. Unknown28 January 2013 at 01:12

    very very professional

    i want to ask how to monitor the PRI status automatically using SNMP or another method that will interact by mail when PRI is Down

    ReplyDelete
  2. Anonymous28 January 2013 at 23:58

    Pleae see below link for explanation of snmp-server enable traps isdn layer2 and Controls SNMP ISDN layer2 transition notifications

    http://www.cisco.com/en/US/customer/docs/ios/netmgmt/command/reference/nm_18.html#wp1014066

    Minor May 19, 2010 2:21:00 PM EDT A demandNbrLayer2Change notification has been received indicating that a D-channel on Rtr_Cisco device, named has layer 1 active but layer 2 not established. Interface Index = 83 Link Status = ISDNLinkInTransition System May 19, 2010 2:21:01 PM EDT System
    Major May 19, 2010 2:20:59 PM EDT A demandNbrLayer2Change notification has been received indicating that a D-channel on Rtr_Cisco device, named has both layers 1 and 2 inactive. Interface Index = 83 Link Status = ISDNLinkDown System May 19, 2010 2:21:00 PM EDT System


    It doesn't tell you specifically which interface is down but at least it narrows it down to the gateway/router. Most of our gateways have only one PRI anyway.


    We use Spectrum One Click for network monitoring.

    Here is L2 back on line:

    May 19, 2010 2:21:01 PM EDT A demandNbrLayer2Change notification has been received indicating that a D-channel on Rtr_Cisco device, named has layer 1 active and layer 2 established. Interface Index = 83 Link Status = ISDNLinkUp System

    ReplyDelete
  3. dasscom5 April 2023 at 00:33

    A pri gateway is required to convert an analogue signal into an IP signal so that organisations may implement cost-effective, efficient solutions. PRI Gateway You can get in touch with us at Dasscom, which is the top producer of the highest calibre pri gateway product.

    ReplyDelete

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