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Show ISDN Status

VERSION 1 
Created on: Jan 27, 2010 6:33 AM by balloon pilot - Last Modified:  Jan 27, 2010 6:35 AM by balloon pilot

Understand the show isdn status Output

This show isdn status output is an example of a properly functioning BRI circuit. In this example, Layer 1 is Active, the Terminal Endpoint Identifiers (TEIs) are successfully negotiated, and ISDN Layer 3 (end-to-end) is ready to make or receive calls. The items you should pay attention to are linked to each corresponding field in the Show ISDN Status Field Descriptions table.

maui-nas-01#show isdn status

The current

ISDN Switchtype

= basic-ni1

ISDN BRI0 interface

Layer 1

Status:

ACTIVE

Layer 2

Status:

TEI = 109, State = MULTIPLE_FRAME_ESTABLISHED

TEI = 110, State = MULTIPLE_FRAME_ESTABLISHED

Spid Status

TEI 109, ces = 1, state = 8(established)

spid1 configured, spid1 sent, spid1 valid

Endpoint ID Info: epsf = 0, usid = 1, tid = 1

TEI 110, ces = 2, state = 8(established)

spid2 configured, spid2 sent, spid2 valid

Endpoint ID Info: epsf = 0, usid = 3, tid = 1

Layer 3 Status

:

0 Active Layer 3 Call(s)

Activated dsl 0 CCBs = 0

Total Allocated ISDN CCBs = 0

Table: Show ISDN Status Field Descriptions

Field

Description

Switchtype

The current ISDN Switchtype = basic-ni1

NI-1 is the only switch type configured on this router. If multiple switch types are configured, then the global switch type and the interface switch type is displayed. The switch type must be obtained from the service provider.

Refer to ISDN Switch Types, Codes, and Values for a list of supported switch-types.

Layer 1 Status

ACTIVE

Layer 1 Status: Verifies physical layer connectivity with the Telco ISDN switch. The most common states are ACTIVE or DEACTIVATED.

Some of the other Layer 1 states are:

  • GOINGDOWN
  • INIT
  • TESTING
  • RESET
  • DELEATED (sic)
  • SHUTDOWN
  • ACTIVATING
  • ACTIVE_ErrorInd

Most of these Layer 1 states are temporary. Use the clear interface bri number command to clear them. If those states persist for extended periods, contact the Telco for further troubleshooting.

Refer to Troubleshooting BRI Layer 1 if the Layer 1 status is not ACTIVE.

Layer 2 Status

TEI=

109,state = MULTIPLE_FRAME_ESTABLISHED

TEI = 110, state =

MULTIPLE_FRAME_ESTABLISHED

Status of ISDN Layer 2 with Terminal Endpoint Identifier (TEI) number and multiframe structure state. The valid TEI number range is 64 to 126. The most often seen Layer 2 states are MULTIPLE_FRAME_ESTABLISHED and TEI_ASSIGNED.

A state=MULTIPLE_FRAME_ESTABLISHED indicates there is data link connectivity to the Telco ISDN switch. This is the state that you should see under normal operations. Any other state usually indicates a problem on the circuit.

A state=TEI_ASSIGNED indicates that the router has lost connectivity to the switch. This is normal if the Telco (commonly in Europe) deactivates Layers 1 and 2 when there are no active calls. If this is not the case, proceed to Troubleshooting BRI Layer 2 for more information on Layer 2 issues.

Refer to Annex B in the ITU Q.921 specifications for more information on all the other possible Layer 2 states such as:

  • TEI_UNASSIGNED
  • ASSIGN_AWAITING_TEI
  • ESTABLISH_AWAITING_TEI
  • AWAITING_ESTABLISHMENT
  • AWAITING_RELEASE
  • TIMER_RECOVERY

These states are often temporary. Use the command clear interface bri number to re-establish Layer 2 connectivity. If those states persist for extended periods use the debug isdn q921 command for further troubleshooting.

A Layer 2 Status of down is indicated by Layer 2 NOT Activated. Refer to Troubleshooting BRI Layer 2 for more information on Layer 2 issues.

SPID Status

TEI 109, ces = 1, state = 8(established)

Terminal Endpoint Identifier (TEI) number and state. A valid dynamic TEI assignment range is 64-126.

The most common state values are:

state = 1(terminal down)

  • state = 3(await establishment)
  • state = 5(init)
  • state = 6(not initialized)
  • state = 8(established)

Only states 5(init) and 8(established) indicate a working BRI circuit. The other states mean the circuit is not properly established.

spid1 configured, spid1 sent, spid1 valid

This is the SPID configuration information for a working BRI. In this example, the SPID is valid. Other commonly observed states are:

  • spid1 configured, no LDN, spid1 sent, spid1 valid
  • spid1 NOT configured, spid1 NOT sent, spid1 NOT valid
  • spid1 configured, spid1 NOT sent, spid1 NOT valid
  • spid1 configured, spid1 sent, spid1 NOT valid

The last three states indicate that either the SPID was not configured or that it is incorrect.

Endpoint ID Info: epsf = 0, usid = 1, tid = 1

Endpoint ID Info: epsf = 0, usid = 3, tid = 1

Endpoint identifier information that can be used by the router to decide which channel will answer the call. The message ENDPOINT ID in the incoming debug isdn q931 can be associated to the User Service IDentifier (usid) and Terminal Identifier (tid). Refer to Configuring SPIDs for Multiple BRIs in a Hunt group for more information.

Layer 3 Status

0 Active Layer 3 Call(s)

Number of active calls.

Activated dsl 0 CCBs = 0

Number of the Digital Signal Link activated. Number of call control blocks in use.

CCB:callid=27, callref=0, sapi=0, ces=1, B-chan=1

Information about the active call. This line does not appear until a call is connected. For a connected call, it displays the caller id information, call reference, and the B-channel it is occupying.

Number of active calls =

Number of active calls. For a BRI this can be a maximum of 2. This line might not appear until a call is connected.

Number of available B-channels =

Number of B channels that are not being used. This line might not appear until a call is connected.

Total Allocated ISDN CCBs =

Number of ISDN call control blocks that are allocated.

Layer 1 Physical Layer Deactivated - Example

This example shows that BRI Layers 1 and 2 are down. The common reasons are that the BRI interface is shut or there is bad cabling. However, to properly troubleshoot this, refer to Troubleshooting ISDN BRI Layer 1.

superchicken#show isdn status

Global ISDN Switchtype = basic-ni

ISDN BRI0 interface dsl 0, interface ISDN Switchtype = basic-ni

Layer 1 Status:

DEACTIVATED

!--- Layer 1 is down.

Layer 2 Status:

Layer 2 NOT Activated

!--- Layer 2 is down

.

Spid Status:

TEI Not Assigned, ces = 1, state = 3(await establishment)

spid1 configured, spid1 NOT sent, spid1 NOT valid

TEI Not Assigned, ces = 2, state = 1(terminal down)

spid2 configured, spid2 NOT sent, spid2 NOT valid

Layer 3 Status:

0 Active Layer 3 Call(s)

Activated dsl 0 CCBs = 0

The Free Channel Mask: 0x80000003

Total Allocated ISDN CCBs = 0

superchicken#

Layer 2 Not Activated - Example

This example shows that BRI Layer 1 is up while Layer 2 is down. Refer to Troubleshooting BRI Layer 2 for more information on how to correct this issue.

superchicken#show isdn status

Global ISDN Switchtype = basic-ni

ISDN BRI0 interface

dsl 0, interface ISDN Switchtype = basic-ni

Layer 1 Status:

ACTIVE

!--- Layer 1 is up

Layer 2 Status:

Layer 2 NOT Activated

!--- Layer 2 is down

Spid Status:

TEI Not Assigned, ces = 1, state = 3(await establishment)

spid1 configured, spid1 NOT sent, spid1 NOT valid

TEI Not Assigned, ces = 2, state = 1(terminal down)

spid2 configured, spid2 NOT sent, spid2 NOT valid

Layer 3 Status:

TWAIT timer active

0 Active Layer 3 Call(s)

Activated dsl 0 CCBs = 0

The Free Channel Mask: 0x80000003

Total Allocated ISDN CCBs = 0

superchicken#

Invalid SPIDs - Example

These examples show that Layer 1 is up and Layer 2 is down due to invalid SPIDs. If you configure the SPIDs correctly, this error should be resolved. Refer to Troubleshooting ISDN BRI SPID for more information.

checker#show isdn status

Global ISDN Switchtype = basic-ni

ISDN BRI0 interface

dsl 0, interface ISDN Switchtype = basic-ni

!--- Interface switch type

Layer 1 Status:

ACTIVE

!--- Layer 1 is up.

Layer 2 Status:

Layer 2 NOT Activated

!--- Layer 2 is not up.

TEI Not Assigned, ces = 1, state = 3(await establishment)

spid1 configured, spid1 NOT sent, spid1 NOT valid

!--- SPID was configured but not sent.

TEI Not Assigned, ces = 2, state = 1(terminal down)

spid2 configured, spid2 NOT sent, spid2 NOT valid

Layer 3 Status:

TWAIT timer active

0 Active Layer 3 Call(s)

Activated dsl 0 CCBs = 0

The Free Channel Mask: 0x80000003

Total Allocated ISDN CCBs = 0

This output shows an example where only one of the SPIDs on the BRI interface was configured incorrectly. Even in such a case, the BRI circuit is not considered fully operational since neither TEI state is established.

maui-soho-02#show isdn status

Global ISDN Switchtype = basic-ni

ISDN BRI0 interface

dsl 0, interface ISDN Switchtype = basic-ni

!--- Interface switch type

Layer 1 Status:

ACTIVE

Layer 2 Status:

TEI = 73, Ces = 2, SAPI = 0, State = TEI_ASSIGNED

TEI = 104, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED

!--- Indicates the circuit is partially up. This is probably

!--- a configuration issue.

Spid Status:

TEI 104, ces = 1, state = 6(not initialized)

!--- TEI is down.

spid1 configured, spid1 sent, spid1 NOT valid

!--- SPID 1 is NOT configured correctly.

TEI 73, ces = 2, state = 1(terminal down)

!--- TEI is down.

spid2 configured, spid2 sent, spid2 valid

!--- SPID 2 is configured correctly.

Endpoint ID Info: epsf = 0, usid = 1, tid = 1

Layer 3 Status:

0 Active Layer 3 Call(s)

Activated dsl 0 CCBs = 0

The Free Channel Mask: 0x80000003

Total Allocated ISDN CCBs = 0

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