Configuring Serial Interfaces Use the information in this chapter to configure serial interfaces. For information on configuring an Asynchronous Transfer Mode (ATM) interface, see the “Configuring ATM Access over a Serial Interface” chapter in the Wide-Area Networking Configuration Guide. See also the section “Configure the CRC” in the section “Configure a Synchronous Serial Interface” in this chapter.
Configure a High-Speed Serial Interface Interface (RSP7000CI). The PA-H provides one high-speed synchronous serial interface, and the PA-2H provides two high-speed synchronous serial interfaces that support full-duplex and data rates up to 52 Mbps. For more information on the PA-H and PA-2H, refer to the PA-H and PA-2H HSSI Port Adapter Installation and Configuration publication.
Specify HSSI Encapsulation Specify HSSI Encapsulation The HSSI supports the serial encapsulation methods, except for X.25-based encapsulations. The default method is HDLC. You can define the encapsulation method by using the following command in interface configuration mode: Command Purpose encapsulation {atm-dxi | hdlc | frame-relay | ppp | sdlc-primary | sdlc-secondary | smds | stun} Configure HSSI encapsulation.
Configure a Synchronous Serial Interface Disable Fair Queueing Disabling fair queuing will dramatically improve fast switching rates over the HSSI. To disable fair queueing, use the following command in interface configuration mode: Command Purpose no fair-queue Disable fair queueing. Configure a Synchronous Serial Interface Synchronous serial interfaces are supported on various serial network interface cards or systems. These interfaces support full-duplex operation at T1 (1.544 Mbps) and E1 (2.
Specify a Synchronous Serial Interface Specify a Synchronous Serial Interface To specify a synchronous serial interface and enter interface configuration mode, use one of the following commands in global configuration mode: Command Purpose interface serial number Begin interface configuration. interface serial slot/port Begin interface configuration for the Cisco 7200 or Cisco 7500 series routers.
Configure a Synchronous Serial Interface By default, synchronous interfaces operate in full-duplex mode. To configure an SDLC interface for half-duplex mode, use the following command in interface configuration mode: Command Purpose half-duplex Configure an SDLC interface for half-duplex mode. BSC is a half-duplex protocol. Each block of transmission is acknowledged explicitly. To avoid the problem associated with simultaneous transmission, there is an implicit role of primary and secondary station.
Configure Half-Duplex and Bisync for Synchronous Serial Port Adapters on Cisco 7200 Series Routers Configure Half-Duplex and Bisync for Synchronous Serial Port Adapters on Cisco 7200 Series Routers The synchronous serial port adapters (PA-8T-V35, PA-8T-X21, PA-8T-232, and PA-4T+) on Cisco 7200 series routers support half-duplex and binary synchronous communications (Bisync). Bisync is a character-oriented data-link layer protocol for half-duplex applications.
Configure a Synchronous Serial Interface You can configure point-to-point compression on serial interfaces that use PPP encapsulation. Compression reduces the size of a PPP frame via lossless data compression. PPP encapsulations support both predictor and Stacker compression algorithms. Note If the majority of your traffic is already compressed files, do not use compression.
Configure Real-Time Transport Protocol Header Compression Configure Real-Time Transport Protocol Header Compression Real-time Transport Protocol (RTP) is a protocol used for carrying packetized audio and video traffic over an IP network. RTP is described in RFC 1889. RTP is not intended for data traffic, which uses TCP or UDP.
Configure a Synchronous Serial Interface Invert the Data If the interface on the PA-8T and PA-4T+ synchronous serial port adapters is used to drive a dedicated T1 line that does not have B8ZS encoding, you must invert the data stream on the connecting CSU/DSU or on the interface. Be careful not to invert data on both the CSU/DSU and the interface because two data inversions will cancel each other out. If the T1 channel on the CT3IP is using AMI line coding, you must invert the data.
Configure DTR Signal Pulsing Configure DTR Signal Pulsing You can configure pulsing DTR signals on all serial interfaces. When the serial line protocol goes down (for example, because of loss of synchronization) the interface hardware is reset and the DTR signal is held inactive for at least the specified interval. This function is useful for handling encrypting or other similar devices that use the toggling of the DTR signal to resynchronize.
Configure a Synchronous Serial Interface To configure the interface so that the router inverts the TXC clock signal, use the following command in interface configuration mode: Command Purpose dte-invert-txc Specify timing configuration to invert TXC clock signal. Specify G.703 and E1-G.703/G.704 Interface Options This section describes the optional tasks for configuring a G.703 serial interface (a serial interface that meets the G.
Configure a Channelized T3 Interface Processor Use Time Slot 16 for Data By default, time slot 16 is used for signaling. It can also be used for data. To specify the use of time slot 16 for data, use the following command in interface configuration mode: Command Purpose ts16 Specify that time slot 16 is used for data. Specify a Clock Source A G.703 interface can clock its transmitted data from either its internal clock or from a clock recovered from the line’s receive data stream.
Configure a Channelized T3 Interface Processor As mentioned above, the CT3IP or PA-CT3/4T1 provides 28 T1 channels for serial transmission of data. Each T1 channel can be configured to use a portion of the T1 bandwidth or the entire T1 bandwidth for data transmission. Bandwidth for each T1 channel can be configured for n x 56 kbps or n x 64 kbps (where n is 1 to 24). The unused portion of the T1 bandwidth, when not running at full T1 speeds, is filled with idle channel data.
Configure the T3 Controller • • Enable BERT Test Pattern Enable Remote FDL Loopbacks After you configure the T1 channels on the CT3IP, you can continue configuring it as you would a normal serial interface. All serial interface commands might not be applicable to the T1 channel. For more information, see the “Configure a Synchronous Serial Interface” section earlier in this chapter.
Configure a Channelized T3 Interface Processor Table 6 CT3IP T1 Channel Defaults Attribute Default Value Speed 64 kbps Framing esf Clock source internal Linecode b8zs T1 yellow alarm detection and generation To specify the timeslots used by each T1 channel, use the following commands beginning in global configuration mode: Step Command Purpose 1 controller t3 slot/port-adapter/port Select the CT3IP and enter controller configuration mode.
Configure External T1 Channels Note If you select ami line coding, you must also invert the data on the T1 channel by using the invert data interface command. To do so, first use the interface serial slot/port-adapter/port:t1-channel global configuration command to select the T1 channel and enter interface configuration mode. Note If you select sf framing, you should consider disabling yellow alarm detection because the yellow alarm can be incorrectly detected with sf framing.
Configure a Channelized T3 Interface Processor To configure a T1 channel as an external port, use the following commands beginning in EXEC mode: Step Command Purpose 1 show controller t3 slot/port-adapter/port Determine if the external device connected to the external T1 port is configured and cabled correctly by locating the line Ext1... in the display output. If the line status is OK, a valid signal is being received and the signal is not an all-ones signal.
Troubleshoot the T3 and T1 Channels Troubleshoot the T3 and T1 Channels You can use the following methods to troubleshoot the CT3IP using Cisco IOS software: • • • Test the T1 by using the t1 test controller configuration command and the test port. Loop the T1 by using loopback interface configuration commands. Loop the T3 by using loopback controller configuration commands.
Configure a Channelized T3 Interface Processor Note Although you can specify a cable length from 0 to 655 feet, the hardware only recognizes the following ranges: 0 to 133, 134 to 266, 267 to 399, 400 to 533, and 534 to 655. For example, entering 150 feet uses the 134 to 266 range. If you later change the cable length to 200 feet, there is no change because 200 is within the 134 to 266 range. However, if you change the cable length to 399, the 267 to 399 range is used.
Troubleshoot the T3 and T1 Channels Figure 12 CT3IP Local Loopback HDLC controllers T1 channels Controller 1 Channel 1 Controller 2 Channel 2 CT3IP T3 output MUX Channel 28 S5681 Controller 28 Figure 13 shows an example of a network line loopback in which just the data is looped back toward the network (before the T1 framer).
Configure a Channelized T3 Interface Processor Figure 14 HDLC controllers CT3IP Network Payload Loopback T1 channels Channel 1 CT3IP Controller 2 Channel 2 MUX Controller 28 Channel 28 T3 output S5683 Controller 1 Figure 15 shows an example of a remote inband loopback in which the network line enters a line loopback.
Monitor and Maintain the CT3IP To enable loopbacks on the T3 (and all T1 channels), use the first command in global configuration mode followed by any one of the following commands: Command Purpose controller t3 slot/port-adapter/port Select the CT3IP and enter controller configuration mode. loopback local Enable the local loopback. loopback network Enable the network loopback. loopback remote Enable the remote loopback. Note The port adapter and port numbers for the CT3IP are 0.
Configure a Channelized T3 Interface Processor Use the show controllers t3 command to display MDL information (received strings). MDL information is displayed only when framing is set to C-bit. Enable Performance Report Monitoring The CT3IP supports performance reports via the Facility Data Link (FDL) per ANSI T1.403. By default, performance reports are disabled.
Enable Remote FDL Loopbacks • • Total bit errors Total bits received When the T1 channel has a BERT test running, the line state is DOWN. Also, when the BERT test is running and the Status field is Not Sync, the information in the total bit errors field is not valid. When the BERT test is done, the Status field is not relevant.
Configure PA-E3 and PA-2E3 Serial Port Adapters The E3 port adapters can transmit and receive data at E3 rates of up to 34 Mbps and use a 75-ohm coaxial cable available from Cisco to connect to a serial E3 network. These port adapters support the following: • • • • • • • • • 16- and 32-bit cyclic redundancy checks (CRC) High-speed HDLC data G.
Troubleshoot the PA-E3 Port Adapter Table 7 PA-E3 Port Adapter Defaults (continued) Command Default Value international bit 00 invert data data is not inverted national bit 0 scramble disabled If you need to change any of the default configuration attributes, use the first command in global configuration mode, followed by any of the optional commands in interface configuration mode: Command Purpose interface serial slot/port-adapter/port (Cisco 7500 series and Cisco 7000 series routers with t
Configure PA-T3 and PA-2T3 Serial Port Adapters Monitor and Maintain the PA-E3 Port Adapter After configuring the new interface, you can display its status. To show current status of the E3 interface on the PA-E3 port adapter, use any of the following commands in EXEC mode: Command Purpose show interfaces serial slot/port-adapter/port (Cisco 7500 series and Cisco 7000 series routers with the RSP7000 and RSP7000CI) Display statistics for the E3 interface.
PA-T3 and PA-2T3 Configuration Task List PA-T3 and PA-2T3 Configuration Task List Perform the tasks in the following sections to configure the PA-T3 (The first task is required; all other tasks are optional.): • • • Configure the PA-T3 Port Adapter Troubleshoot the PA-T3 Port Adapter Monitor and Maintain the PA-T3 Port Adapter For PA-T3 port adapter configuration examples, see the “PA-T3 and PA-2T3 Configuration Example” section, later in this chapter.
Configure PA-T3 and PA-2T3 Serial Port Adapters Command Purpose invert data Invert the data stream on the interface. scramble Enable scrambling on the interface. Troubleshoot the PA-T3 Port Adapter To set the following loopbacks to troubleshoot the PA-T3 port adapter using Cisco IOS software, use the first command in global configuration mode, followed by any of the other commands depending on your needs: Command Purpose loopback dte Loopback after the LIU toward the terminal.
Configure a Packet OC-3 Interface Configure a Packet OC-3 Interface The Cisco Packet OC-3 Interface Processor (POSIP) and Packet OC-3 Port Adapter (POSPA) are available on Cisco 7200 and Cisco 7500 series routers. The POS is a fixed-configuration interface processor that uses second-generation Versatile Interface Processor (VIP2) technology. The POS provides a single 155.520-Mbps, OC-3 physical layer interface for packet-based traffic.
Configure a Packet OC-3 Interface Select a Packet OC-3 Interface The Packet OC-3 interface is referred to as pos in the configuration commands. An interface is created for each POS found in the system at reset time.
Configure an Interface for Line Loopback To enable or disable internal loopback on the interface, use one of the following commands in interface configuration mode: Command Purpose loop internal Enable internal loopback. no loop internal Disable internal loopback. Local loopback is useful for checking that the POS is working. Packets from the router are looped back in the framer. Configure an Interface for Line Loopback Line loopback is used primarily for debugging purposes.
Configure Automatic Protection Switching of Packet-over-SONET Circuits Configure an Alarm Indication Signal To configure line alarm indication signals (LAIS) when the POS interface is placed in any administrative shut down state, use the following command in interface configuration mode: Command Purpose pos ais-shut Send line alarm indication signals.
Configure APS Working and Protect Interfaces Perform the first task in the following section to configure APS and POS (The other tasks are optional.): • • • • • Configure APS Working and Protect Interfaces Configure Other APS Options Monitor and Maintain APS Configure SONET Alarm Reporting Configure Protection Switch Configure APS Working and Protect Interfaces This section describes how to configure a working and protect interface. The commands listed in this section are required.
Configure Automatic Protection Switching of Packet-over-SONET Circuits Configure Other APS Options To configure the other APS options, use any of the following commands in interface configuration mode. The commands listed in this section are optional. Command Purpose aps authenticate string Enable authentication and specify the string that must be present to accept any packet on the OOB communication channel.
Configure SONET Alarm Reporting Configure SONET Alarm Reporting To configure the thresholds and the type of SONET alarms that are reported, use any of the following commands in interface configuration mode. The commands listed in this section are optional. The default settings are adequate for most POS installations.
Configure Serial Interfaces for CSU/DSU Service Modules Fractional T1/FT/WIC CSU/DSU Service Module Configuration Task List To configure fractional T1 and T1 (FT1/T1) service modules, perform the tasks described in these sections: • • • • • • • • • Specify the Clock Source Enable Data Inversion before Transmission Specify the Frame Type of a FT/T1 Line Specify the CSU Line Build Out Specify FT1/T1 Line-Code Type Enable Remote Alarms Enable Loopcodes that Initiate Remote Loopbacks Specify Timeslots Enable
Specify the Frame Type of a FT/T1 Line Specify the Frame Type of a FT/T1 Line To specify the frame type for a line using the FT1/T1 CSU/DSU module, use the following command in interface configuration mode: Command Purpose service-module t1 framing {sf | esf} Specify a FT1/T1 frame type. Choose either D4 Super Frame (sf) or Extended Super Frame (esf). In most cases, the service provider determines which framing type, either esf or sf, is required for your circuit.
Configure Serial Interfaces for CSU/DSU Service Modules Enable Remote Alarms To generate remote alarms (yellow alarms) at the local CSU/DSU or detect remote alarms sent from the remote CSU/DSU, use the following command in interface configuration mode: Command Purpose service-module t1 remote-alarm-enable Enable remote alarms. Remote alarms are transmitted by the CSU/DSU when it detects an alarm condition, such as a red alarm (loss of signal) or blue alarm (unframed 1’s).
Specify Timeslots The no form of this command disables loopback requests. For example, the no service-module t1 remote-loopback full command ignores all full-bandwidth loopback transmissions and requests. Configuring the no form of the command may not prevent telco line providers from looping your router in esf mode, because fractional T1/T1 telcos use facilities data-link messages to initiate loopbacks.
Configure Serial Interfaces for CSU/DSU Service Modules To configure the router to send SNMP traps, use the following commands: Step Command Purpose interface serial slot/port Enter interface configuration mode. (slot/port corresponds to where the WIC card is installed in your router) service-module t1 fdl {ansi | att} Set the fdl parameter to either ansi or att. Exit interface configuration mode. more system:running-config Verify that the fdl parameter has been changed.
Enable Scrambled Data Coding You can use the following line speed settings: 2.4, 4.8, 9.6, 19.2, 38.4, 56, 64 kpbs, and an auto setting. The 64-kbps line speed cannot be used with back-to-back digital data service (DDS) lines. The subrate line speeds are determined by the service provider. Only the 56-kbps line speed is available in switched mode. Switched mode is the default on the 2-wire CSU/DSU and is enabled by the service-module 56k network-type interface configuration command on the 4-wire CSU/DSU.
Configure Serial Interfaces for CSU/DSU Service Modules In switched mode, you need additional dialer configuration commands to configure dial-out numbers. Before you enable the service-module 56k network-type switched command, both CSU/DSU’s must use a clock source coming from the line and the clock rate configured to auto or 56k kbps. If the clock rate is not set correctly, this command will not be accepted. The 2-wire and 4-wire, 56/64-kbps CSU/DSU modules use V.
Configure Low-Speed Serial Interfaces Configure Low-Speed Serial Interfaces This section describes how to configure low-speed serial interfaces.
Configure Low-Speed Serial Interfaces After idling for a defined number of milliseconds, the state machine asserts a request to send (RTS) signal and changes to the wait-clear-to-send (CTS) state for the data communications equipment (DCE) to assert CTS. A timeout timer with a value set by the half-duplex timer rts-timeout command starts. This default is 3 ms. If the timeout timer expires before CTS is asserted, the state machine returns to the ready state and deasserts RTS.
Understand Half-Duplex DTE and DCE State Machines Figure 18 Half-Duplex DCE Transmit State Machine Timer expires [constant-carrier mode] Start transmission Timer expires [controlled-carrier mode] Set timer = transmit-delay Ready state Transmit delay state Timer expires Start transmission Assert DCD Set timer = dcd-txstart-delay DCDtxstart delay state Transmit state S4540 Transmit queue no longer empty More frames to transmit Continue transmission No more frames to transmit Transmission finished
Configure Low-Speed Serial Interfaces 4 The DCE transitions to the wait DCD drop delay state. This state causes a time delay between the transmission of the last frame and the deassertion of DCD in the controlled-carrier mode for DCE transmits. 5 When the timer expires, the DCE deasserts DCD and transitions back to the ready state and stays there until there is a frame to transmit on that interface.
Tune Half-Duplex Timers Place a Low-Speed Serial Interface in Controlled-Carrier Mode To place a low-speed serial interface in controlled-carrier mode, use the following command in interface configuration mode: Command Purpose half-duplex controlled-carrier Place a low-speed serial interface in controlled-carrier mode.
Serial Interface Configuration Examples In synchronous mode, low-speed serial interfaces support all interface configuration commands available for high-speed serial interfaces, except the following two commands: • • sdlc cts-delay sdlc rts-timeout When placed in asynchronous mode, low-speed serial interfaces support all commands available for standard asynchronous interfaces. The default is synchronous mode.
HSSI Configuration Examples Configure Specific IP Addresses for an Interface Example This example shows how to configure the access server so that it will use the default address pool on all interfaces except interface 7, on which it will use an address pool called lass: ip address-pool local ip local-pool lass 172.30.0.
Serial Interface Configuration Examples For more information, refer to the “Configure the T3 Controller” and “Configure External T1 Channels” sections earlier in this chapter.
PA-E3 Serial Port Adapter Configuration Example CT3IP Performance Monitoring Example In the following example, the performance reports are generated for T1 channel 6 on the CT3IP in slot 9: controller t3 9/0/0 t1 6 fdl ansi CT3IP BERT Test Pattern Example The following example shows how to enable a BERT test pattern that consists of a repeating pattern of ones (...111...
Serial Interface Configuration Examples PA-T3 and PA-2T3 Configuration Example The following example shows a typical configuration for serial interface 1/0/0 on a PA-T3 serial port adapter in a Cisco 7500 series router. The dsu bandwidth command reduces the bandwidth by padding the T3 frame, and the dsu mode command enables and improves interoperability with other DSUs. Router# configure terminal Router(config)# interface serial 1/0/0 Router(config-if)# ip address 1.1.1.10 255.255.255.
APS Configuration Examples APS Configuration Examples The following examples show how to configure basic APS on a router and how to configure more than one protect/working interface on a router by using the aps group command. Basic APS Configuration The following example shows the configuration of APS on Router A and Router B (see Figure 20). In this example, Router A is configured with the working interface, and Router B is configured with the protect interface.
Serial Interface Configuration Examples switchover to the protect interface 3/0/0 on Router B because they are both in APS group 10. Similarly, if the working interface 2/0/0 on Router B becomes unavailable, the connection will switchover to the protect interface 3/0/0 on Router A because they are both in APS group 20.
CSU/DSU Service Module Examples CSU/DSU Service Module Examples Two main categories of service module examples are provided: • • FT1/T1 Examples 2- and 4-wire, 56/64-kpbs Service Module Examples FT1/T1 Examples FT1/T1 examples are provided for these configurations: • • • • • • • • • • Specify a T1 Frame Type Example Specify the CSU Line Build Out Example Specify T1 Line-Code Type Example Enable Loopcodes Example Specify Timeslots Example Display a Performance Report Example Enable Loopback Line Exampl
Serial Interface Configuration Examples Enable Loopcodes Example The following interactive example displays two routers connected back-to-back through an FT1/T1 line: Router# no service-module t1 remote-loopback full Router# service-module t1 remote-loopback payload alternate Router# loopback remote full %SERVICE_MODULE-5-LOOPUPFAILED: Unit 0 - Loopup of remote unit failed Router# service-module t1 remote-loopback payload v54 Router# loopback remote payload %SERVICE_MODULE-5-LOOPUPFAILED: Unit 0 - Loopup o
CSU/DSU Service Module Examples Enable Loopback Line Examples The following example shows how to configure a payload loopback: Router1# loopback line payload Loopback in progress Router1# no loopback line The following example shows the output when you loop a packet in switched mode without an active connection: Router1# service-module 56k network-type switched Router1# loopback line payload Need active connection for this type of loopback % Service module configuration command failed: WRONG FORMAT.
Serial Interface Configuration Examples 2- and 4-wire, 56/64-kpbs Service Module Examples Examples for 2- and 4-wire, 56/64 kpbs service modules are provided for the following configurations: • • • • • • Set the Network Line Speed Examples Enable Scrambled Data Coding Example Enable Switched Dial-Up Mode Example Display a Performance Report Example Remote Loopback Request Example Select a Service Provider Example Set the Network Line Speed Examples The following interactive example displays two routers
CSU/DSU Service Module Examples Enable Scrambled Data Coding Example The following example scrambles bit codes in 64-kbps DDS mode: Router# service-module 56k clock rate 56 Router# service-module 56k data-coding scrambled Can configure scrambler only in 64k speed DDS mode % Service module configuration command failed: WRONG FORMAT.
Serial Interface Configuration Examples E1-G.703/G.704 Serial Port Adapter Example The following example shows a configuration for serial interface 9/1/3 on a E1-G.703/G.704 serial port adapter in a Cisco 7500 series router. In this example, the interface is configured for framed (G.704) operation, and timeslot 16 is used for data. Router# configure terminal Router(config)# interface serial 9/1/3 Router(config-if)# ip address 1.1.1.10 255.255.255.
Low-Speed Serial Interface Examples The following example shows some typical synchronous serial interface configuration commands available when the interface is in synchronous mode: interface serial 2 physical-layer sync ip address 1.0.0.2 255.0.0.
Serial Interface Configuration Examples Ethernet interfaces and their subinterfaces are configured for LAN access. interface Ethernet0 ip address 10.1.1.1 255.255.255.0 media-type 10BaseT ! interface Ethernet1 ip address 10.1.2.1 255.255.255.0 media-type 10BaseT ! Interfaces serial 0 and serial 1 are the high-speed serial interfaces on the first 2T16S module. In this example, subinterfaces are also configured for remote offices connected in to interface Serial 0.
Low-Speed Serial Interface Examples no ip address encapsulation frame-relay ! interface Serial5.1 point-to-point description PVC to first office ip address 10.1.9.1 255.255.255.0 frame-relay interface-dlci 16 ! interface Serial5.2 point-to-point description PVC to second office ip address 10.1.10.1 255.255.255.0 frame-relay interface-dlci 17 ! interface Serial6 description configuration for PPP interface ip address 10.1.11.1 255.255.255.
Serial Interface Configuration Examples ! interface Serial17 no ip address shutdown Interface serial 18 is the first high-speed serial interface of the second 2T16S module. Remote sites on different subnets are dialing in to this interface with point-to-point and multipoint connections. interface Serial18 description Frame relay sample no ip address encapsulation frame-relay ! interface Serial18.1 point-to-point description Frame relay subinterface ip address 10.1.14.1 255.255.255.
Low-Speed Serial Interface Examples ! interface Serial23 no ip address shutdown ! interface Serial24 no ip address shutdown ! !Serial interfaces 23 through 35 would appear here. !... router eigrp 10 network 10.0.0.
Serial Interface Configuration Examples IC-134 Cisco IOS Interface Configuration Guide
