Cisco IOS Release 12.0 Dial Solutions Configuration Guide - Configuring Channelized E1 & T1 [Cisco IOS Software Releases 12.0 Mainline]

Table Of Contents

Configuring Channelized E1 and Channelized T1

Background Information

About In-Band and Out-of-Band Signaling

About Channelized E1 and T1 on the Cisco AS5200

Configure ISDN PRI

Request PRI Line and Switch Configuration from a Telco Service Provider

Configure Channelized E1 ISDN PRI

Configure Channelized T1 ISDN PRI

Configure the Serial Interface

Specify an IP Address for the Interface

Configure Encapsulation

Configure Network Addressing

Configure ISDN Calling Number Identification

Configure ISDN Voice Calls

Configure Inclusion of the Sending Complete Information Element

Configure NSF Call-by-Call Support

Configure Multiple ISDN Switch Types

Configure B Channel Outgoing Call Order

Perform Configuration Self-Tests

Monitor and Maintain ISDN PRI Interfaces

Configure Robbed-Bit Signaling for Analog Calls over T1 Lines

Configure Channel-Associated Signaling for Analog Calls over E1 Lines

Configure Channel-Associated Signaling

Troubleshoot Channelized E1 and Channelized T1

Troubleshoot Channelized E1 and T1 Controllers

Run Controller Loopback Diagnostic Tests

Local Loopback

Remote Loopback

Channelized E1 Controller Loopback

Troubleshoot Channelized E1 and T1 Channel Groups

Interface Local Loopback

Interface Remote Loopback

Configure Switched 56k Digital Dial-In over Channelized T1 and Robbed-Bit Signaling

Functional Description

Switched 56k and Analog Modem Calls into T1 CAS

Basic Call Processing Components

ISDN BRI Calls into T1 CAS

Configure Switched 56k Services

Configure E1 R2 Signaling

Functional Description

Configure E1 R2 Signaling

Monitor E1 R2 Signaling

Troubleshoot E1 R2 Signaling

Configure R1 Modified Signaling

Configure R1 Modified Signaling

Configure R1 Modified Signaling on a T1 Interface

Configure R1 Modified Signaling on an E1 Interface

Channelized E1 and Channelized T1 Configuration Examples

ISDN PRI Examples

NSF Call-by-Call Support Example

PRI on a Cisco AS5200 Examples

Multiple ISDN Switch Types Examples

Outgoing B Channel Ascending Call Order Example

PRI Groups and Channel Groups on the Same Channelized T1 Controller Example

Robbed-Bit Signaling Examples

Allocating All Channels for Robbed-Bit Signaling Example

Mixing and Matching Channels Example

Switched 56k Configuration Examples

Switched 56k T1 Controller Example

Mixture of Switched 56k and Modem Calls over CT1 CAS

Switched 56k and Analog Modem Calls over Separate T1 CAS Lines

Comprehensive Switched 56k Startup Configuration Example

ISDN Channel-Associated Signaling Examples

Allocate All Channels for Channel-Associated Signaling

Mix and Match Channels

E1 R2 Signaling Examples

R1 Modified Signaling Configuration Example

Configuring Channelized E1 and Channelized T1

Channelized T1 and channelized E1 can be configured for ISDN PRI, synchronous serial, and asynchronous serial communications.

Channelized T1 and channelized E1 are supported by corresponding controllers. Each T1 or E1 controller has one physical network termination, but it can have many virtual interfaces, depending on the configuration.

This chapter describes how to configure channelized E1 and channelized T1 for ISDN PRI and for two types of signaling to support analog calls over digital lines. The following main configuration sections are provided:

•Configure ISDN PRI

•Configure Robbed-Bit Signaling for Analog Calls over T1 Lines (Cisco AS5200)

•Configure Channel-Associated Signaling for Analog Calls over E1 Lines (Cisco AS5200)

•Troubleshoot Channelized E1 and Channelized T1

•Configure Switched 56k Digital Dial-In over Channelized T1 and Robbed-Bit Signaling (Cisco AS5200 and cisco AS5300)

•Configure E1 R2 Signaling (Cisco AS5200 and Cisco AS5300)

•Configure R1 Modified Signaling

In addition, this chapter describes how to run interface loopback diagnostics on channelized E1 and channelized T1. For more information, see the "Troubleshoot Channelized E1 and Channelized T1" section.

For hardware technical descriptions, and for information about installing the controllers and interfaces, refer to the hardware installation and maintenance publication for your particular product.

For a complete description of the channelized E1/T1 commands in this chapter, refer to the Dial Solutions Command Reference. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.

Background Information

This section presents background information about signaling and about the use of channelized E1/T1 on the Cisco AS5200.

About In-Band and Out-of-Band Signaling

The terms in-band and out-of-band indicate whether various signals—used to set up, control, and terminate calls—travel in the same channel (or band) with users' voice calls or data, or whether those signals travel a separate channel (or band).

ISDN, which uses the D channel for signaling and the B channels for user data, fits into the out-of-band signaling category.

Robbed-bit signaling, which uses bits from specified frames in the user data channel for signaling, fits into the in-band signaling category.

Channel-associated signaling, which uses E1 timeslot 16 (the D channel) for signaling, fits into the out-of-band signaling category.

About Channelized E1 and T1 on the Cisco AS5200

On a Cisco AS5200, you can allocate the available channels for channelized E1 or T1 in the following ways:

•All channels can be configured to support ISDN PRI.

•If you are not running ISDN PRI, all channels can be configured to support robbed-bit signaling (also known as channel-associated signaling), which enables a Cisco AS5200 modem to receive and transmit analog calls.

•All channels can be configured in a single channel group. For configuration information about this leased line or non-dial use, see the "Configuring Serial Interfaces" chapter in the Configuration Fundamentals Configuration Guide.

•Mix and match channels supporting ISDN PRI and channel grouping.

•Mix and match channels supporting ISDN PRI, robbed-bit signaling, and channel grouping across the same T1 line. For example, on the same channelized T1 you can configure the pri-group timeslots 1-10 command, channel-group 11 timeslots 11-16 command, and cas-group 17 timeslots 17-23 type e&m-fgb command. This is a rare configuration because it requires you to align the correct range of timeslots on both ends of the connection.

See the "PRI Groups and Channel Groups on the Same Channelized T1 Controller Example," "Robbed-Bit Signaling Examples," and the "ISDN Channel-Associated Signaling Examples" sections at the end of this chapter.

Configure ISDN PRI

This section describes tasks that are required to get ISDN PRI up and running. This section does not address routing issues, dialer configuration, and dial backup. For information about those topics, see the "Dial-on-Demand Routing" part of this manual.

ISDN PRI is supported on the Cisco 7200 series and 7500 series routers using T1 or E1 versions of the Multichannel Interface Processor (MIP) card, on the Cisco 4000 series channelized E1/T1/PRI network processor module (NPM), and on the Cisco AS5200. Channelized T1 ISDN PRI offers 23 B channels and 1 D channel. Channelized E1 ISDN PRI offers 30 B channels and 1 D channel. Channel 24 is the D channel for T1, and channel 16 is the D channel for E1.

For a complete description of the commands mentioned in this chapter, refer to the Dial Solutions Command Reference.

Perform the tasks in the following sections to configure ISDN PRI:

•Request PRI Line and Switch Configuration from a Telco Service Provider

•Configure Channelized E1 ISDN PRI

•Configure Channelized T1 ISDN PRI

•Configure the Serial Interface

•Configure NSF Call-by-Call Support

•Configure Multiple ISDN Switch Types (optional)

•Configure B Channel Outgoing Call Order (optional)

•Perform Configuration Self-Tests (optional)

•Monitor and Maintain ISDN PRI Interfaces (optional)

See the end of this chapter for the "ISDN PRI Examples" section.

Note   After the ISDN PRI interface and lines are operational, configure the D channel interface for DDR. The DDR configuration specifies the packets that can trigger outgoing calls, specifies whether to place or receive calls, and provides the protocol, address, and phone number to use.

For DDR configuration information, see the "Dial-on-Demand Routing" part of this manual. For command information, refer to the Dial Solutions Command Reference.

Request PRI Line and Switch Configuration from a Telco Service Provider

Before configuring ISDN PRI on your Cisco router, you need to order a correctly provisioned ISDN PRI line from your telecommunications service provider.

This process varies dramatically from provider to provider on a national and international basis. However, some general guidelines follow:

•Verify if the outgoing B channel calls are made in ascending or descending order. Cisco IOS default is descending order however, if the service providers switch is configured for outgoing calls made in ascending order, the router can be configured to match the service providers switch configuration.

•Ask for delivery of calling line identification. Providers sometimes call this CLI or Automatic Number Identification (ANI).

•If the router will be attached to an ISDN bus (to which other ISDN devices might be attached), ask for point-to-multipoint service (subaddressing is required) and a voice-and-data line.

When you order ISDN service, request the PRI switch configuration attributes displayed in .

Table 24 PRI Switch Configuration Attributes to Request from Service Vendor

Attribute

Value

Line format

Extended Superframe Format (ESF)

Line coding

Binary 8-zero substitution (B8ZS)

Call type

23 incoming channels and 23 outgoing channels

Speed

64 kbps

Call-by-call capability

Enabled

Channels

23 B+D

Trunk selection sequence

Either ascending order (from 1 to 23) or descending order (from 23 to 1)

B + D glare

Yield

Directory numbers

Only 1 directory number assigned by service provider

ISDN call speed outside local exchange

Speed set to 56 kbps outside local exchange

SPIDs required?

None

Configure Channelized E1 ISDN PRI

To configure ISDN PRI on a channelized E1 controller, use the following commands, beginning in global configuration mode:

Step

Command

Purpose

1

isdn switch-type switch-type

Select a service provider switch type that accommodates PRI. (See for a list of supported switch type keywords.)

2

controller e1 slot/port

controller e1 number

Define the controller location in the Cisco7200 or Cisco 7500 series by slot and port number.
or
Define the controller location in the Cisco 4000 series or the Cisco AS5200 universal access server by unit number.¹

3

framing crc4

Define the framing characteristics as cyclic redundancy check 4 (CRC4).

4

linecode hdb3

Define the line code as high-density bipolar 3 (HDB3).

5

pri-group [timeslots range]

Configure ISDN PRI.

¹Controller numbers range 0 through 2 on the Cisco 4000 series and 1 to 2 on the Cisco AS5200.

If you do not specify the time slots, the specified controller is configured for 30 B channels and one D channel. The B channel numbers range 1 to 31; channel 16 is the D channel for E1. Corresponding serial interfaces numbers range 0 to 30. In commands, the D channel is interface serial controller-number:15. For example, interface serial 0:15.



Table 25 ISDN Service Provider PRI Switch Types

Keywords by Area

Switch Type

  none

No switch defined

Australia and Europe

  primary-net5

ISDN PRI switch type for Europe, New Zealand, Australia, and Asia (covers the Euro-ISDN E-DSS1 signaling system and is compliant with European Telecommunication Standards Institute or ETSI).

Japan

  primary-ntt

Japanese ISDN PRI switches

North America

  primary-4ess

AT&T 4ESS switch type for the U.S.

  primary-5ess

AT&T 5ESS switch type for the U.S.

  primary-dms100

NT DMS-100 switch type for the U.S.

  primary-ni

AT&T National ISDN switch type

Note   Cisco IOS Release 11.3T introduced ISDN switch type changes. The command parser will still accept the following switch types: basic-nwnet3, vn2, and basic-net3; however, when viewing the NVRAM configuration, the basic-net3 or vn3 switch types are displayed respectively. For specific details about ISDN switch type changes, refer to the "National ISDN Switch Types for Basic Rate and Primary Rate Interfaces" document in Cisco IOS Release 11.3(3)T.

Configure Channelized T1 ISDN PRI

To configure ISDN PRI on a channelized T1 controller, use the following commands beginning in global configuration mode:

Step

Command

Purpose

Step 1

isdn switch-type switch-type

Select a service provider switch type that accommodates PRI. (See for a list of supported PRI switch type keywords.)

Step 2

controller t1 slot/port
or
controller t1 number

Specify a T1 controller on a Cisco 7500
or
Specify a T1 controller on a Cisco 4000.¹

Step 3

framing esf

Define the framing characteristics as Extended Superframe Format (ESF).

Step 4

linecode b8zs

Define the line code as binary 8 zero substitution (B8ZS).

Step 5

pri-group [timeslots range]²

Configure ISDN PRI.

If you do not specify the time slots, this controller is configured for 23 B channels and 1 D channel.

¹Controller numbers range 0 through 2 on the Cisco 4000 series and 1 to 2 on the Cisco AS5200.

²On channelized T1, timeslots range 1 to 24. You can specify a range or timeslots (or example, pri-group timeslots 12-24) if other timeslots are used for non-PRI channel groups.

If you do not specify the time slots, the specified controller is configured for 24 B channels and one D channel. The B channel numbers range 1 to 24; channel 24 is the D channel for T1. Corresponding serial interfaces numbers range 0 to 23. In commands, the D channel is interface serial controller-number:23. For example, interface serial 0:23.

Configure the Serial Interface

When you configure ISDN PRI on the channelized E1 or channelized T1 controller, in effect you create a serial interface that corresponds to the PRI group timeslots This interface is a logical entity is associated with the specific controller. After you create the serial interface by configuring the controller, you must configure the D channel serial interface. The configuration applies to all the PRI B channels (timeslots).

To configure the D channel serial interface, complete the tasks in the following sections:

•Specify an IP Address for the Interface

•Configure Encapsulation

•Configure Network Addressing

•Configure ISDN Calling Number Identification

•Configure ISDN Voice Calls (optional)

•Configure ISDN Voice Calls

Specify an IP Address for the Interface

To configure the D channel serial interface created for ISDN PRI, use the following commands beginning in global configuration mode:

Step

Command

Purpose

1

interface serial slot/port:23
interface serial number:23

interface serial slot/port:15
interface serial number:15

Specify D channel on the serial interface for channelized T1.

Specify D channel on the serial interface for channelized E1.

2

ip address ip-address

Specify an IP address for the interface.

When you configure the D channel, its configuration is applied to all the individual B channels.

Configure Encapsulation

PPP encapsulation is configured for most ISDN communication. However, the router might require a different encapsulation for traffic sent over a Frame Relay or X.25 network, or the router might need to communicate with devices that require a different encapsulation protocol.

Configure encapsulation as described in one of the following sections:

•Configure PPP Encapsulation

•Configure Encapsulation for Frame Relay or X.25 Networks

•Configure Encapsulation for Combinet Compatibility

In addition, the router can be configured for automatic detection of encapsulation type on incoming calls. To configure this feature, complete the tasks in the following section:

•Configure Automatic Detection of Encapsulation Type of Incoming Calls

Configure PPP Encapsulation

Each ISDN B channel is treated as a serial line and supports HDLC and PPP encapsulation. The default serial encapsulation is HDLC. To configure PPP encapsulation, use the following command in interface configuration mode:

Command

Purpose

encapsulation ppp

Configure PPP encapsulation.

Configure Encapsulation for Frame Relay or X.25 Networks

If traffic from this ISDN interface crosses a Frame Relay or X.25 network, the appropriate addressing and encapsulation tasks must be completed as required for Frame Relay or X.25 networks.

See the "Configuring Frame Relay" chapter or "Configuring X.25 and LAPB" chapter for more information about addressing, encapsulation, and other tasks necessary to configure Frame Relay or X.25 networks.

Configure Encapsulation for Combinet Compatibility

Historically, Combinet devices supported only the Combinet Proprietary Protocol (CPP) for negotiating connections over ISDN B channels. To enable Cisco routers to communicate with those Combinet bridges, the Cisco IOS software supports a new CPP encapsulation type.

To enable routers to communicate over ISDN interfaces with Combinet bridges that support only CPP, use the following commands in interface configuration mode:

Step

Command

Purpose

Step 1

encapsulation cpp

Specify CPP encapsulation.

Step 2

cpp callback accept

Enable CPP callback acceptance.

Step 3

cpp authentication

Enable CPP authentication.

Now most Combinet devices support PPP. Cisco routers can communicate over ISDN with these devices by using PPP encapsulation, which supports both routing and fast switching.

Combinet devices support only IP, IPX, and bridging. For AppleTalk, Cisco routers automatically perform half-bridging with Combinet devices. For more information about half-bridging, see the "Configure PPP Half-Bridging" section in the "Configuring Media-Independent PPP" chapter of this publication.

Cisco routers can also half-bridge IP and IPX with Combinet devices that support only CPP. To configure this feature, you only need to set up the addressing with the ISDN interface as part of the remote subnet; no additional commands are required.

Configure Automatic Detection of Encapsulation Type of Incoming Calls

You can enable a serial or ISDN interface to accept calls and dynamically change the encapsulation in effect on the interface when the remote device does not signal the call type. For example, if an ISDN call does not identify the call type in the Lower Layer Compatibility fields and is using an encapsulation that is different from the one configured on the interface, the interface can change its encapsulation type at that time.

This feature enables interoperation with ISDN terminal adapters that use V.120 encapsulation but do not signal V.120 in the call setup message. An ISDN interface that by default answers a call as synchronous serial with PPP encapsulation can change its encapsulation and answer such calls.

Automatic detection is attempted for the first 10 seconds after the link is established or the first five packets exchanged over the link, whichever is first.

To enable automatic detection of encapsulation type, use the following commands in interface configuration mode:

Command

Purpose

autodetect encapsulation encapsulation-type

Enable automatic detection of encapsulation type on the specified interface.

You can specify one or more encapsulations to detect. Cisco IOS software currently supports automatic detection of PPP and V.120 encapsulations.

Configure Network Addressing

When you configure networking, you specify how to reach the remote recipient. To configure network addressing, use the following commands beginning in interface configuration mode:

Step

Command

Purpose

1

dialer map protocol next-hop-address name hostname speed 56|64 dial-string[:isdn-subaddress]

dialer map protocol next-hop-address name hostname spc [speed 56 | 64] [broadcast] dial-string[:isdn-subaddress]

Define the remote recipient's protocol address, host name, and dialing string; optionally, provide the ISDN subaddress; set the dialer speed to 56 or 64 kbps, as needed.
or
(Australia) Use the spc keyword that enables ISDN semipermanent connections.

2

dialer-group group-number

Assign the interface to a dialer group to control access to the interface.

3

dialer-list dialer-group list access-list-number

Associate the dialer group number with an access list number.

4

access-list access-list-number {deny | permit} protocol source address source-mask destination destination-mask

Define an access list permitting or denying access to specified protocols, sources, or destinations.

Australian networks allow semipermanent connections between customer routers with PRIs and the TS-014 ISDN PRI switches in the exchange. Semipermanent connections are offered at better pricing than leased lines.

Packets that are permitted by the access list specified in are considered interesting and cause the router to place a call to the destination protocol address that is identified in both and .

Note   The access list reference in Step 4 of this task list is an example of the access list commands allowed by different protocols. Some protocols might require a different command form or might require multiple commands. Refer to the relevant protocol chapter in the Network Protocols Configuration Guide, Part 1, Part 2, or Part 3 for more information about setting up access lists for a protocol.

For more information about defining outgoing call numbers, see the "Configuring Legacy DDR" or "Configuring Dialer Profiles" chapter.

Configure ISDN Calling Number Identification

A router might need to supply the ISDN network with a billing number for outgoing calls. Some networks offer better pricing on calls in which the number is presented. When configured, the calling number information is included in the outgoing Setup message.

To configure the interface to identify the billing number, use the following commands in interface configuration mode:

Command

Purpose

isdn calling-number calling-number

Specify the calling party number.

This command can be used with all ISDN PRI switch types.

Configure ISDN Voice Calls

All incoming ISDN analog modem calls that come in on an ISDN PRI receive signaling information from the ISDN D channel. The D channel is used for circuit switched data calls and analog modem calls. To enable all incoming ISDN voice calls to access the Cisco AS5200 and AS5300 call switch module and integrated modems, use the following command beginning in interface configuration mode:

Command

Purpose

isdn incoming-voice modem

Route incoming ISDN modem calls to the modem module.

Configure Inclusion of the Sending Complete Information Element

In some geographic locations, such as Hong Kong and Taiwan, ISDN switches require that the Sending Complete information element be included in the outgoing Setup message to indicate that the entire number is included. This information element is not required in other locations.

To configure the interface to include the Sending Complete information element in the outgoing call Setup message, use the following command in interface configuration mode:

Command

Purpose

isdn sending-complete

Include the Sending Complete information element in the outgoing call Setup message.

Configure NSF Call-by-Call Support

Network-Specific Facilities (NSF) are used to request a particular service from the network or to provide an indication of the service being provided. Call-by-call support means that a B channel can be used for any service; its use is not restricted to a certain preconfigured service, such as incoming 800 calls or an outgoing 800 calls. This specific NSF call-by-call service supports outgoing calls configured as voice calls.

This NSF call-by-call support feature is vendor-specific; only routers connected to AT&T Primary-4ESS switches need to configure this feature. This feature is supported on channelized T1.

To enable the router to for NSF call-by-call support and, optionally, to place outgoing voice calls, complete use the following steps:

Step 1 Configure the controller for ISDN PRI.

Step 2 Configure the D channel interface to place outgoing calls, using the dialer map command with a dialing-plan keyword. You can enter a dialer map command for each dialing plan to be supported.

Step 3 Define the dialer map class for that dialing plan.

To define the dialer map class for the dialing plan, use the following command beginning in global configuration mode:

Step

Command

Purpose

1

map-class dialer classname

Specify the dialer map class, using the dialing-plan keyword as the classname.

2

dialer voice-call

(Optional) Enable voice calls.

3

dialer outgoing classname

Configure the specific dialer map class to make outgoing calls.

Note   To set the called party type to international, the dialed number must be prefaced by 011.

Table 26 lists the NSF dialing plans and supported services offered on AT&T Primary-4ESS switches.

Table 26 NSF Supported Services on AT&T Primary-4ESS Switches

NSF Dialing Plan

Data

Voice

International

Software Defined Network (SDN)¹

Yes

Yes

GSDN (Global SDN)

MEGACOMM

No

Yes

Yes

ACCUNET

Yes

Yes

Yes

¹The dialing plan terminology in this table is defined and used by AT&T.

Configure Multiple ISDN Switch Types

The Multiple ISDN Switch Types feature allows you to configure more than one ISDN switch type per router. You can apply an ISDN switch type on a per interface basis, thus extending the existing global isdn switch-type command to the interface level. This allows Primary Rate Interfaces (PRI) and Basic Rate Interfaces (BRI) and to run simultaneously on platforms that support both interface types.

A global ISDN switch type is required and must be configured on the router before you can configure a switch type on an interface. To configure multiple ISDN switch types for a PRI interface using a channelized E1 or channelized T1 controller, use the following command in global configuration mode:

Command

Purpose

isdn switch-type switch-type

Apply a global ISDN switch type.

You must ensure the ISDN switch type is valid for the ISDN interfaces on the router. lists valid ISDN switch types for BRI and PRI interfaces.

Note   When you configure an ISDN switch type on the channelized E1 or T1 controller, this switch type is applied to all timeslots on that controller. For example, if you configure channelized T1 controller 1:23, which corresponds to serial interface 1, with the ISDN switch type of primary-net5, then all timeslots on serial interface 1 (and T1 controller 1) will use the primary-net5 switch type.

The following restrictions apply to Multiple ISDN Switch Types:

•You must configure a global ISDN switch type using the existing isdn switch-type global configuration command before you can configure the ISDN switch type on an interface. Since global commands are processed before interface level commands, the command parser will not accept the isdn switch-type command on an interface unless a switch type is first added globally. Using the isdn switch-type global command allows for backward compatibility.

•If an ISDN switch type is configured globally, but not at the interface level, then the global switch type value is applied to all ISDN interfaces.

•If an ISDN switch type is configured globally and on an interface, then the interface level switch type supersedes the global switch type at initial configuration. For example, if the global BRI switch type defined is basic-net3, and the interface level BRI switch type is basic-ni, then the basic-ni switch type is the value applied to that BRI interface.

•The ISDN global switch type value is only propagated to the interface level on initial configuration or router reload. If you reconfigure the global ISDN switch type, the new value is not applied to subsequent interfaces. Therefore, if you require a new switch type for a specific interface, you must configure that interface with the desired ISDN switch type.

•If an ISDN global switch type is not compatible with the interface type you are using, or you change the global switch type and it is not propagated to the interface level, as a safety mechanism, the router will apply a default value to the interface level as follows:

Global Switch Type

BRI Interface

PRI Interface

basic-net3

basic-net3

primary-net5

primary-ts014

basic-ts013

primary-ts014

primary-ni

basic-ni

primary-ni

If, for example, you reconfigure the router to use global switch type basic-net3, the router will apply a primary-net5 switch type to PRI interfaces and basic-net3 to any BRI interfaces. You can override the default switch assignment by configuring a different ISDN switch type on the associated interface.

Configure B Channel Outgoing Call Order

You can configure the router to select the first available B channel in ascending order (channel B1) or descending order (channel B23 for a T1 and channel B30 for an E1). To configure the optional task of selecting B channel order for outgoing calls for PRI interface types, use the following command in interface configuration mode:

Command

Purpose

isdn bchan-number-order {ascending | descending}

Enable B channel selection for outgoing calls on a PRI interface (optional).

Before configuring the ISDN PRI on your router, check with your service vendor to determine if the ISDN trunk call selection is configured for ascending or descending order. If there is a mismatch between the router and switch with regard to channel availability, the switch will send back an error message stating the channel is not available. By default, the router will select outgoing calls in descending order.

Perform Configuration Self-Tests

To test the router's ISDN configuration, we suggest that you use the following commands:

Command

Purpose

show controllers t1 slot/port

Check Layer 1 (physical layer) of the PRI over T1.

show controllers e1 slot/port

Check Layer 1 (physical layer) of the PRI over E1.

debug q921

Check Layer 2 (data link layer).

debug isdn events

debug q931

debug dialer

show dialer

Check Layer 3 (network layer).

See the Debug Command Reference for information about the debug commands.

Monitor and Maintain ISDN PRI Interfaces

Use the following commands to monitor and maintain ISDN interfaces:

Command

Purpose

show interfaces serial slot/port bchannel channel-number (Cisco 7500 series)

show interfaces serial number bchannel channel-number (Cisco 4000 series)

Display information about the physical attributes of the ISDN PRI over T1 B and D channels.

show interfaces serial slot/port bchannel channel-number (Cisco 7500 series)

show interfaces serial number bchannel channel-number (Cisco 4000 series)

Display information about the physical attributes of the ISDN PRI over E1 B and D channels.

show controllers t1 [slot/port] (Cisco 7500 series)

show controllers t1 number (Cisco 4000 series)

Display information about the T1 links supported on the ISDN PRI B and D channels.

show controllers e1 [slot/port] (Cisco 7500 series)

show controllers e1 number (Cisco 4000 series)

Display information about the E1 links supported on the ISDN PRI B and D channels.

show isdn {active | history | memory | services | status [dsl | serial number] | timers}

Display information about current calls, history, memory, services, status of PRI channels, or Layer 2 or Layer 3 timers. (The service keyword is available for PRI only.)

show dialer [interface type number]

Obtain general diagnostic information about the specified interface.

Configure Robbed-Bit Signaling for Analog Calls over T1 Lines

The Cisco AS5200 supports robbed-bit signaling for receiving and transmitting analog calls on T1 lines. Robbed-Bit signaling emulates older analog trunk and line in-band signaling methods that are transmitted in many networks.

In countries that support T1 framing (such as the United States and Canada), many networks send supervisory and signaling information to each other by removing the 8th bit of each timeslot of the 6th and 12th frame for superframe (SF) framing. For networks supporting extended superframe (ESF) framing, the 6th, 12th, 18th, and 24th frames are affected. This is done to support channel banks in the network that convert various battery and ground operations on analog lines into signaling bits the Robbed-bits are forwarded over digital lines.

Robbed-bit signaling configured on the Cisco AS5200 enables the integrated modems in the access server to answer and transmit analog calls. To support analog signaling over T1 lines on the Cisco AS5200, robbed-bit signaling must be enabled.

Note   The signal type configured on the access server must match the signal type offered by your telco provider. Ask your telco provider which signal type to configure on each T1 controller.

The Cisco AS5200 has two controllers: controller T1 1 and controller T1 0, which must be configured individually.

To configure robbed-bit signaling support for calls made and received, use the following commands beginning in global configuration mode:

Step

Command

Purpose

1

controller t1 0

Enable the T1 0 controller, and enter controller configuration mode.

2

cablelength long dbgain-value dbloss-value

If the channelized T1 line connects to a smart jack instead of a CSU, set pulse equalization (use parameter values specified by your telco service provider).

3

framing esf

Set the framing to match your telco service provider's offering, which in most cases is esf.

4

linecode b8zs

Set the line code type to match your telco service provider's offering, which in most cases is b8zs.

5

clock source line primary

Configure one T1 line to serve as the primary or most stable clock source line.

6

cas-group channel-number timeslots range type signal

Configure channels to accept voice calls.

This step creates interfaces that you can configure.

7

fdl {att | ansi}

Set the facilities data link exchange standard for the CSU, as specified by your telco service provider.

If you want to configure robbed-bit signaling on the other T1 controller, repeat Steps 1 through 7, making sure in Step 5 to select T1 controller 1's line as the secondary clock source.

If you want to configure ISDN on the other controller, see the "Configure ISDN PRI" section of this chapter. If you want to configure channel groupings on the other controller, see the "Configuring Synchronous Serial Ports" chapter in this manual; specify the channel groupings when you specify the interface.

Configure Channel-Associated Signaling for Analog Calls over E1 Lines

The Cisco AS5200 and AS5300 Universal Access Servers supports channel-associated signaling for channelized E1 lines, which are commonly deployed in networks in Latin America, Asia, and Europe. Channel-associated signaling is configured to support channel banks in the network that convert various battery and ground operations on analog lines into signaling bits, which are forwarded over digital lines.

Channel-associated signaling is call signaling that is configured on an E1 controller and enables the access server to send or receive analog calls. The signaling uses the16th channel (timeslot); thus, channel-associated signaling fits in the out-of-band signaling category.

Once channel-associated signaling is configured on a single E1 controller, up to 30 remote users can simultaneously dial in to the Cisco AS5200 and Cisco AS5300 through networks running the R2 protocol. The R2 protocol is an international signaling standard for analog connections. Because R2 signaling is not supported in the Cisco AS5200 and Cisco AS5300, an E1-to-E1 converter is required. See .

Because the Cisco AS5200 and Cisco AS5300 have more than one physical E1 port on the dual E1 PRI board, up to 60 simultaneous connections can be made through one dual E1 PRI board.

Figure 228 Remote PC Accessing Network Resources through the Cisco AS5200

Note   For information on how to configure an Anadigicom E1-to-E1 converter, refer to the documentation that came with the converter.

Note   The dual E1 PRI card must be installed in the Cisco AS5200 before you can configure channel-associated signaling.

Configure Channel-Associated Signaling

To configure the Cisco AS5200's E1 controllers, use the following commands, beginning in global configuration mode:

Step

Command

Purpose

1

controller e1 number

Define the controller location in the Cisco AS5200/AS5300 by unit number, ranging from 1 to 2.

2

cas-group channel-number timeslots range type signal

Configure channel-associated signaling and the R2 signaling protocol on a specified number of timeslots.

3

framing crc4

Define the framing characteristics as cyclic redundancy check 4 (CRC4).

4

linecode hdb3

Define the line code as high-density bipolar 3 (HDB3).

5

clock source line primary¹

Specify one E1 line to serve as the primary or most stable clock source line.

¹Specify the other E1 line as the secondary clock source with the clock source line secondary command.

If you do not specify the time slots, channel-associated signaling is configured on all 30 B channels and one D channel on the specified controller.

Troubleshoot Channelized E1 and Channelized T1

When troubleshooting channelized T1 or E1, you must first determine if the problem is with a particular channel group or with the T1 or E1 line.

If the problem is with a single channel group, you have a potential interface problem.

If the problem is with the T1 or E1 line, or with all channel groups, you have a potential controller problem.

The following sections describe how to determine whether the problem affects an interface or a controller:

•Troubleshoot Channelized E1 and T1 Controllers

•Troubleshoot Channelized E1 and T1 Channel Groups

Troubleshoot Channelized E1 and T1 Controllers

When you troubleshoot E1 or T1 controllers, first check that the configuration is correct. The framing type and line code should match to what the service provider has specified. Then check channel group and PRI-group configurations, especially to verify that the timeslots and speeds are what the service provider has specified.

At this point, the show controller t1 or show controller e1 commands should be used to check for T1 or E1 errors. Use the command several times to determine if error counters are increasing, or if the line status is continually changing. If this is occurring, you need to work with the service provider.

Note   Cisco routers do not have CSU capability and do not react to any remote loopback codes at the T1 or E1 level.

Run Controller Loopback Diagnostic Tests

Controller loopback tests are a means to isolate problems and are available for both channelized T1 controllers and channelized E1 controllers. The following loopback tests are documented for isolating T1 and E1 controller issues:

•Local Loopback (channelized T1 controller)

•Remote Loopback (channelized T1 controller)

•Channelized E1 Controller Loopback

Local Loopback

The local loopback loops the controller both toward the router and toward the line. Since the loopback is done internally to the router, the controller should transition to the UP state within approximately 10 seconds, and no further T1 errors should be detected.

All channel groups will be looped back; if the encapsulation on that channel group supports loopbacks (for example, HDLC and PPP), you can test that channel group by pinging the interface address. For example, if you have assigned an IP address to the serial interface defined for a channel group, you can ping that IP address.

To place the controller into local loopback, use the following command in controller configuration mode.

Command

Purpose

loopback local (controller)

Loop the T1 controller toward the router and toward the line.

To test a channel group, use the following command in EXEC mode:

Command

Purpose

ping protocol protocol-address

Ping the interface address.

Check errors by using the following command in EXEC mode:

Command

Purpose

show controllers t1

Check errors.

If any errors occur, or the controller fails to change to the UP state, please contact the Cisco Technical Assistance Center (TAC).

Since the controller local loopback is bidirectional, the service provider can test the line integrity using a T1 BERT test set.

Remote Loopback

The second T1 controller loopback is a remote loopback. This loopback can be used only if the entire T1 goes to a remote CSU. This is not the case with 99.9% of channelized T1. When the loopback remote controller command is executed, an inband CSU loop-up code will be sent over the entire T1, which will attempt to loop up the remote CSU. To place the controller in remote loopback, use the following command in controller configuration mode:

Command

Purpose

loopback remote (controller)

Place the T1 controller in remote loopback.

Note   If controller loopbacks are used, they will disrupt service for all channel groups on that interface.

Channelized E1 Controller Loopback

For the E1 controller, only the local loopback is available. Local loopback operates the same as the local loopback on the T1 controller, forming a bidirectional loopback, both toward the router and toward the line. To place the E1 controller in local loopback, use the following command in controller configuration mode:

Command

Purpose

loopback (controller)

Place the E1 controller in local loopback toward the router and toward the line.

All channel groups will be looped back; if the encapsulation on that channel group supports loopbacks (for example, HDLC and PPP), you can test that channel group by pinging the interface address. For example, if you have assigned an IP address to the serial interface defined for a channel group, you can ping that IP address.

To place the controller into local loopback, use the following command in controller configuration mode.

Command

Purpose

loopback local (controller)

Loop the T1 controller toward the router and toward the line.

To test a channel group, use the following command in EXEC mode:

Command

Purpose

ping protocol protocol-address

Ping the interface address.

Check errors if any. by using the following command in EXEC mode:

Command

Purpose

show controllers t1

Check errors.

If any errors occur, it is most likely a hardware problem; please contact the Cisco TAC. In addition, you can ask the service provider to test the line by using a T1 BERT test set.

Troubleshoot Channelized E1 and T1 Channel Groups

Each channelized T1 or channelized E1 channel group is treated as a separate serial interface. To troubleshoot channel groups, first verify configurations and check everything that is normally checked for serial interfaces. You can verify that the timeslots and speed are correct for the channel group by checking for CRC errors and aborts on the incoming line.

Note   None of the Cisco channelized interfaces will react to any loop codes. To loop a channelized interface requires that the configuration command be entered manually.

Two loopbacks are available for channel groups:

•Interface Local Loopback

•Interface Remote Loopback

Interface Local Loopback

Interface local loopback is a bidirectional loopback, which will loopback toward the router and toward the line. The entire set of timeslots for the channel group are looped back. The service provider can use a BERT test set to test the link from the central office to your local router, or the remote router can test using pings to their local interface (which will go from the remote site, looped back at your local site, and return to the interface on the remote site).

To place the serial interface (channel group) into local loopback, use the following command in interface configuration mode:

Command

Purpose

loopback local

Place the serial interface (channel group) in local loopback.

Interface Remote Loopback

Remote loopback is the ability to put the remote DDS CSU/DSU in loopback. It will work only with channel groups that have a single DS0 (1 timeslot), and with equipment that works with a latched CSU loopback as specified in AT&T specification TR-TSY-000476, "OTGR Network Maintenance Access and Testing." To place the serial interface (channel group) in remote loopback, use the following command in interface configuration mode:

Command

Purpose

loopback remote (interface)

Place the serial interface (channel group) in remote loopback.

Using the loopback remote interface command sends a latched CSU loopback command to the remote CSU/DSU. The router must detect the response code, at which time the remote loopback is verified.

Configure Switched 56k Digital Dial-In over Channelized T1 and Robbed-Bit Signaling

Internet Service Providers can provide switched 56 kbps access to their customers using a Cisco AS5300 or Cisco AS5200. Switched 56k digital dial-in enables many services for ISPs. When using traditional ISDN PRI, the access server uses the bearer capability to determine the type of service. However when providing switched 56k over a CT1 RBS connection, the DS0s in the access server can be configured to provide either modem or 56 kbps data service. The dial-in user can access a 56 kbps data connection using either an ISDN BRI connection or a 2- or 4-wire switched 56 kbps connection. The telco to which the access server connects must configure its switches to route 56 kbps data calls and voice (modem) calls to the appropriate DS0.

Likewise, an enterprise can provide switched 56 kbps digital dial-in services to its full time telecommuters or small remote offices using ISDN PRI or a CT1 RBS connection.

Switched 56k digital dial-in offers the following benefits:

•Enables ISDN BRI clients to connect to a Cisco AS5300 or Cisco AS5200 over switched 56k and T1 CAS.

•Provides switched 56k dial-in services over T1 CAS to remote clients that do not have access to ISDN BRI. For example, a remote PC making digital calls over a 2- or 4-wire switched 56 kbps connection and a CSU.

The following prerequisites apply to the Switched 56k Digital Dial-In feature:

•The remote device could be an ISDN BRI end point such as a terminal adapter or BRI router. In this scenario, the CSU/DSU is irrelevant. For 2- or 4-wire switched 56k remote clients, the remote end point must be compatible with the carrier's service. Different carriers may implement different versions switched 56k end points.

•A CSU/DSU must be present at the remote client side of the connection. Otherwise, switched 56k connections are not possible. The Cisco AS5300 and Cisco AS5200 access servers have built-in CSU/DSUs.

•The telco must configure its side of the T1 connection to deliver 56 kbps data calls to the correct range of DS0s. If you do not want to dedicate all the DS0s or timeslots on a single T1 to switched 56k services, be sure to negotiate with the telco about which DS0s will support switched 56k and which DS0s will not.

•Cisco IOS Release 11.3(2)T or later must be running on the access server.

The following apply to Switched 56k digital dial-in:

•A Cisco AS5300 or Cisco AS5200 only supports incoming switched 56k calls. Dialing out with switched 56k is not supported at this time.

•Switched 56k over E1 is not supported. Only switched 56k over T1 is supported.

•Analog modem calls are not supported over DS0s that are provisioned for switched 56k. For a configuration example, see the"Switched 56k and Analog Modem Calls over Separate T1 CAS Lines" in this chapter.

•Certain types of T1 lines, such as Loop Start and Ground Start, might not support this service. Contact you