Configuring T1/E1 and ISDN PRI Options Chapter 14 Configuring T1/E1 and ISDN PRI Options

Objectives Upon completion of this chapter, you will be able to perform the following tasks: Identify channelized T1 and E1 configuration commands Identify ISDN PRI configuration commands

Configuring T1 and E1

Channelized T1/E1 Overview 30 Subchannels 24 Subchannels E1 T1 MUX MUX Wide-area connectivity has become an integral part of large corporate and organization networking Dedicated serial lines can connect to digital carrier facilities to transmit data through the telephone hierarchy. Several technologies are key features of this WAN connectivity. They include: T1-A digital WAN service that transfers data at 1.544 Mbps through the telephone-switching network. T1 service is provided in the United States and Japan. E1-Wide-area digital transmission scheme used predominantly in Europe and Australia that carries data at a rate of 2.048 Mbps. Channelized T 1-Access link operating at 1.544 Mbps that is subdivided into 24 channels of 64 kbps each. The individual channels or groups of channels connect to different destinations. Channelized Tl supports PPP, HDLC, Frame Relay, and X.25. Also referred to as fractional T1 Channelized E 1-Access link operating at 2.048 Mbps that is subdivided into 30 B channels at D channel. Channelized El supports PPP, ILC, Frame Relay, and X.25. DS-0 (digital signal level 0}-Framing specification used in transmitting digital signals over a single channel at Ei4 kbps on a T1/El facility. DS-0 is the data rate of each T1/E1 channel DS-1 (digital signal level l) Framing specification used in transmitting digital signals at 1.544 Mbps. Multiplexer (MUX) - A method of combining multiple input ports to run over a trunk T1 multiplexers use time-dimension multiplexing (TDM) to combine multiple channels into a single byte stream. DS-0 framing for a single 64-kbps channel DS-1 framing for a single 1. 544-Mbps T1 or 2.108-Mbps E1

Channelized T1/E1 Overview 64 kbps FSIP 4-port Fast Serial Interface Processor CSU/DSU 64 kbps Public Data Network CSU/DSU 64 kbps CSU/DSU 64 kbps CSU/DSU Cisco 7000 64 kbps Subshannels 0-23 Becomes T1/E1 Port 0 Private Data Network MIP MultiChannel interface Processor (Channelized T1/E1) MUX Many organizations have based their WAN structures on dedicated lines using individual CSU/DSUs. Each of these lines was located on a multiple-port synchronous serial interface card. The port density of the interface card and the backplane capacity were limiting factors in how many WAN connections a router could support. T1 and E1 support increases the port density and overall throughput for WAN implementations. The Cisco 7000 models support the MultiChannel Interface Processor (MIP) that contains two full T1/El ports. The Cisco 4000 models support a single-port interface for channelized T1/E1. Each port can be channelized to generate 24 DS-0 (64 kbps) lines for Tl or 30 DS-0 lines for E1. Multiple MIP cards can be configured into the Cisco 7000 chassis. Each line (subchannel) is individually configurable as though it were a dedicated interface. The output of a port on the MIP card can be carried by a private data network. Alternatively, the MIP card can be connected directly to the service provider's facility, and the channel output can be carried by a public data network. T1 and E1 support the following WAN protocols: X.25  LAPB Frame Relay  HDLC PPP  SMDS ATM-DXI 64 kbps Subshannels 0-23 Public Data Network Port 1 Cisco 7000 LAPB HDLC SMDS

Channelized T1/E1 Configuration Router (config) # Controller [t1 | e1] [slot/port | number] Configures T1 or E1 controller and enters controller configuration mode Router (config-controller) # Use the controller [t1 I e1] command to configure a Tl or E1 controller and to enter the controller configuration mode. controller Command Description slot/port Specifies MIP slot and port number. number Specifies the network interface module (MM) number. For example, to configure the MIP in slot 4, port 0 of a Cisco 7000 as a T1 controller, use the controller t1 4/0 command. To configure MM 0 of a Cisco 4000 as a T1 controller, use the controller tl 0 command. Use the channel-group command to define the time slots that belong to each TlB1 circuit. channel-group Command Description number Channel-group number from 0 to 23 for Tl and 0 to 31 for 1 timeslots range Time slot or range of time slots belonging to the channel group. For a T1 controller, the time slot range is from 1 to 24. For an E1 controller, the time slot range is from 1 to 31. 48|56|64 Speed in kbps.The default line speed for a T1 controller is 56 kbps. For an El controller, the default is 64 kbps. The channel-group number may be arbitrarily assigned and must be unique for the controller. The time slot range must match the time slots assigned to the channel group. The service provider defines the time slots that comprise a channel group. Channel-group number timeslots range speed { 48 | 56 | 64 } Specifies the channel group (subchannel) associated with each time slot

Channelized T1 Configuration Router (config-controler) # framing { sf | esf } Defines the framing type required for a fractional T1 data line Router (config-controller) # linecode { ami | b8zs } Specifies the line code type required for communication with the service provider Use the framing command to select the frame type for the T1 line. framing Command Description sf Specifies Super Frame as the Tl frame type. Super Frame is the default. esf Specifies Extended Super Frame as the T1 frame type. Use the linecode command to select the line-code type for the T1 line. linecode Command Description ami Specifies alternate mark inversion (AMI) as the line-code type. ami is the default. b8zs Specifies B8ZS as the line-code type. The service provider determines the framing type and the line code. Normally, the clock source sources from the Tl line rather than the router interface. Use the clock source command to set the Tl line clock source for the controller. This command is only required when connecting two devices back-to-back for testing purpose's. The clock source internal command specifies that the interface will clock its transmitted data from its internal clock. The clock source line command specifies the T1 line as the clock source. This is the default condition. Router (config-controller) # clock source { line | internal } Sets the clock source

Channelized T1 Configuration Example MultiChannel Interface Processor T1 Line (Port 1) (Slot 4) Cisco 7000 controller t1 4/1 framing esf line code b8zs clock source line channel-group 0 timeslots 1 channel-group 8 timeslots 6-11 ! Interface serial 4/1:0 ip address 172.16.13.1 255.255.255.0 encapsulation ppp Interface serial 4/1:8 ip address 172.16.1.1 255.255.255.0 The MIP card allows up to 24 (Tl) subchannels to be configured independently on one physical port. Subchannels have all the same configuration options and characteristics as ordinary serial ports. Channel groups are assigned from one or several DS-0s, which are assigned by the carrier and are usually numbered contiguously. In the example: Command Description controller t1 4/1 Specifies the MIP card in slot 4, port i of a Cisco 7000. framing esf Specifies Extended Super Frame as the Tl frame type. line code b8zs Specifies B8ZS as the line-code type. channel-group 0 timeslots 1 Specifies that circuit 0 is a single time slot. channel-group 8 timeslots 6-11 Specifies that channel-group 8 will have six time slots (6 to 11) The line speed is the T1 default speed, 56 kbps. The controller card in slot 4 has port 1 configured for the appropriate frame and line-code types. Channel group 0 has a single time slot running at the default (56 kbps) speed. Channel group 8 has been assigned six time slots, all operating at the default 56 kbps. Subchannel 0 has been assigned an encapsulation type of PPP Channel group 8 assumes the default encapsulation. Both subchannels are assigned to different subnets. The line encoding and framing must be set to match the carrier equipment. After you define T1 channel groups, you can configure each channel group as a serial interface. In this example, the interface serial 4/1:0 command configures channel group 0 for PPP

Channelized E1 Configuration Router (config-controller) # framing { crc4 | no-crc4 } [ australia ] Defines the framing type required for a fractional E1 data line Router (config-controller) # Use the framing command to select the frame type for the El line. framing Command Description crc4 Specifies crc4 as the El frame type, the default. no-crc4 Specifies that CRC checking is disabled in the E1 frame type. australia (Optional) Specifies the frame type for E1 lines in Australia. Use the linecode command to select the line-code type for the E1 line. linecode Command Description ami Specifies AMI as the line-code type, the default. hdb3 Specifies high-density bipolar 3 (HDB3) as the line-code type. Use hdb3 for El controllers only. linecode { ami | hdb3 } Specifies the line-code type required for communication with the service provider

Channelized E1 Configuration Example MultiChannel Interface Processor E1 Line (Port 1) (Slot 4) Cisco 7000 controller e1 4/1 framing crc4 line code hdb3 clock source line channel-group 0 timeslots 1 channel-group 8 timeslots 5,7,12-15,28 ! Interface serial 4/1:0 ip address 172.16.13.1 255.255.255.0 encapsulation ppp Interface serial 4/1:8 ip address 172.16.1.1 255.255.255.0 The MIP card allows up to 30 (El) subchannels to be configured independently on one physical port. Subchannels have all the same configuration options and characteristics as ordinary serial ports. Channel groups are assigned from one or several 64-kbps DS-0s, which are assigned by the carrier and are usually numbered contiguously. In the example: Command Description controller e1 M1 Specifies the MIP card in slot 4, port 1 of a Cisco 7000 framing crc4 Specifies Extended Super Frame as the E1 frame type. line code hdb3 Specifies HDB3 as the line-code type. channel-group 0 timeslots 1 Specifies that circuit 0 is a single time slot. channel-group 8 timeslots Specifies that channel-group 8 will have seven time slots (5, 5,7,12-15, 28 7, 12-15, and 28). The line speed is the E1 default speed, 64 kbps. The controller card in slot 4 has port 1 configured for the appropriate frame and line-code types. Channel group 0 has a single time slot running at the default (64 kbps) speed. Channel group 8 has been assigned various time slot ranges, totaling seven, all operating at the default rate of 64 kbps. Subchannel 0 has been assigned an encapsulation type of PPP Subchannel 8 assumes the default encapsulation. Both subchannels are assigned to different subnets. The line encoding and framing must be set to match the carrier equipment. The channel group speed you choose must match the speed specified by your service provider. The interface serial 4/1:8 command configures channel group 8 as a serial interface.

Configuring Primary Rate Interface

ISDN PRI Is 23B+D (or 30B+D) Cisco 7000 T1/E1 link ISDN 64-kbps D channel for B channel-call setup D All PRI channels are 64 kbps (DS-0) 23/30 B The Primary Rate Interface (PRI) is an ISDN interface that multiplexes multiple channels across a single transmission medium. PRI is sometimes described as 23B+D, or as 30B+D and has the following configurations: ISDN PRI in North America and Japan offers 23 B channels and 1 D channel, yielding a combined rate of 1.544 Mbps. ISDN PRI in Europe provides 30 B channels and 1 D channel with a combined rate of 2.048 Mbps. Unlike ISDN BRI, PRI does not connect to an NTl. device. The physical interface is the same as for a T1 or an E1-that is, a CSU/DSU function bundled into the router. D-channel packet data is not available for PRI. Interface B Channels Where used T1 PRI 23 North America and Japan E1 PRI 30 Europe and rest of the World

Configuring for PRI Select PRI switch type CSU/DSU ISDN Select PRI switch type Specify T1/E1 controller, framing and line coding for the facility Set PRI group time slot for T1/E1 and indicate speed used Specify the interface on the router that you will configure for DDR Use PRI configuration tasks in addition to the DDR-derived commands you saw earlier in BRI configurations. PRI tasks are: Step 1 Specify the correct PRI switch type that the router interfaces at the provider's central office. Step 2 Specify the T1/E1 controller, framing type, and line coding for the provider's facility. Step 3 Set a PRI group time slot for the T1/E1 facility and indicate the speed used. Step 4 Identify the interface that you will configure to act with DDR (PRI D channel).

ISDN PRI Configuration Router (config) # isdn switch-type primary rate switch type Specifies ISDN PRI service switch type Router (config) # controller { t1 | e1 } slot/port | number Configures T1/E1 controller Use the isdn switch-type command to specify the central office PRI switch to which the router connects. isdn switch-type Command Description pri-4ess AT&T 4ESS-Primary switches (United States). pri-Sess AT&T SESS-Primary switches (United States). pri-dmsl00 NT DSM-100 PRI switches (North America). pri-ntt NTT ISDN PRI switches (Japan). pri-net5 European ISDN PRI switches. none No switch defined. The controller {tl | el} slot/port number global command identifies a controller. controller {t1 | e1} slot/port Description Command t1 Select a controller interface for North American and Japanese facility interfaces. e1 Controller interface for European facilities and facilities used in much of the rest of the world.

T1/E1 Controller Options for PRI Router (config-controller) # framing { esf | crc4 } Selects the framing type on the router processor or module to interface ISDN PRI service Router (config-controller) # Use the framing controller configuration to specify the time slot frame type to use with the Tl or facility. framing Command Description esf Extended Super Frame. Use for T1 PRI configurations. crc4 Cyclic redundancy check 4. Use for El PRI configurations. Use the linecode controller configuration to specify the physical-layer line coding to use with the provider's T1 or El facility. linecode Command Description b8zs Binary 8-zero substitution. Use for T1 PRI configurations. hdb3 High-density bipolar 3. Use for E1 PRI configurations. linecode { b8zs | hdb3 } Selects the line code type on the router processor or module to interface ISDN PRI service

ISDN PRI Configuration Router (config-controller) # pri-goup [ timeslot range ] Specifies ISDN PRI on the router’s channelized T1/E1 card and sets appropriate speed Router (config) # interface serial slot/port | number: { 23 | 15 } The pri-group command configures the specified interface for PRI operation. pri-group Command Description timeslots range The number of time slots allocated. For T1, use a value in the range of 1 to 23, and for E1 use a value from 1 to 31. PRI is not available in every country. The interface serial slot/port I unit:{23 | 15} command specifies an interface for PRI operation (D channel). interface serial Command Description slot/port A slot/port designated on the Cisco router. 23 A T1 interface that designates channelized DS-0s 0 to 22 are B channels and DS-0 23 is the D channel. 15 An E1 interface that designates 30 DS-0s are B channels and DS-0 15 is the D channel. Additional commands pertain to Tl and El operation. For T1, enter the commands framing esf and linecode b8zs. For E1, enter the commands framing crc4 and linecode hdb3.

PRI Configuration Example Cisco 7500 CSU/DSU 4ESS ISDN T1 isdn switch-type primary-4ess ! controller t1 2/0 pri-group timeslots 1-23 framing esf linecode b8zs interface serial 2/0:23 !(set ip address, dialer, provider config statements) ip address 172.16.11.2 255.255.255.0 In the example: Command Description isdn switch-type primary-4ess Selects a switch type of 4ESS to use on the Cisco 7000. controller tl 2/0 Selects the T1 controller for slot 2. pri-group timeslots 1-23 Establishes the interface port to function as PRI with 23 time slots designated to operate at a speed of 64 kbps. framing esf Selects Extended Super Frame, a T1 choice. linecode b8zs Selects line-code binary 8-zero substitution for T1. interface serial 2/0:23 Use serial interface slot 2, port 0. Channel 23 has the D channel (T1)

Summary This chapter presented the following serial line features: Channelized T1 Channelized E1 ISDN PRI