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Configuring the Cisco 1-, 2-, and 4-port Serial Network Interface Modules for Cisco 4400 Series ISRs
This document provides information that you should know to perform the configuration tasks for configuring required and optional features of the Cisco 1-, 2-, and 4-port Serial Network Interface Modules on the Cisco 4400 Series Integrated Services Routers (ISRs). This document contains the following sections:
The Cisco 1-port, 2-port, and 4-port Serial Network Interface Modules (NIMs) are multi-protocol synchronous serial NIMs supported on the Cisco 4400 Series ISRs. The Cisco 1-, 2-, and 4-port Serial NIMs expand the capabilities of the router to provide connectivity for synchronous interfaces in a wide range of applications including up to 8Mbps date rate for high speed high-level data link control (HDLC). These capabilities can be utilized as Point-to-Point Cisco HDLC WAN interface or frame relay interface. The Cisco 1-, 2-, and 4-port Serial NIM software is capable of anti-counterfeit protection and provides periodic system status information. The Cisco 1-, 2-, and 4-port Serial NIMs have their own serial communication controllers (SCCs) and they do not rely on the host platform for SCCs. For more information on the Cisco 1-, 2-, and 4-port Serial NIM LED and hardware features, see the Hardware Installation Guide .
Cyclic redundancy checking (CRC) is an error-checking technique that uses a calculated numeric value to detect errors in transmitted data. All the Serial HWIC interfaces use a 16-bit frame check sequence (FCS) CRC by default. The sender of a data frame calculates the FCS. The sender appends the FCS value to the message before sending a frame.The receiver recalculates the FCS and compares its calculation to the FCS from the sender. If there is a difference between the two calculations, the receiver assumes that a transmission error occurred and sends a resend request to the sender. See the Step 4 for configuring CRC.
The Cisco 1-, 2-, and 4-port Serial NIM interfaces support both the data terminal equipment (DTE) and data communication equipment (DCE) mode, depending on the mode of the compact serial cable attached to the port. To use a port as a DTE interface, you only need to connect a DTE compact serial cable to the port. When the system detects the DTE mode cable, it automatically uses the external timing signal. To use a port in DCE mode, you must connect a DCE compact serial cable and set the clock speed with the clock rate configuration command. See Step 4 for setting up a clock rate.
Encapsulation protocols connect the layer- 2 (link layer) protocols with the layer-3 (network layer) protocols. When traffic crosses a WAN link, the connection needs a layer 2 protocol to encapsulate traffic. The Cisco 1-, 2-, and 4-port Serial NIM interfaces support the High-Level Data Link Control (HDLC), Point-to-point (PPP), and Frame Relay encapsulation protocols. The HDLC protocol, is the router proprietary protocol that decodes proprietary framing used by the routers on the PPP links. The standard PPP protocol supports the PPP links analyzed by the HDLC and can also be utilized for Frame Relay. The standard Frame Relay encapsulation protocol is a versatile and common encapsulation protocol used with Frame Relay. See Step 4 to set the encapsulation method.
- Enhanced Object Tracking
- Setting up NIM Bring up Time
- NRZI Line-Coding Format
- Enabling DTR Pulse-Time
- Monitoring DSR As a Line Up/Down Indicator
- Ignoring Input Signals
- Inverting the Clock Signal
On your serial NIM, you can enable the Enhanced Object Tracking (EOT) feature to consider the carrier-delay timer when tracking the status of an interface. The carrier-delay command in tracking configuration mode enables tracking to consider the carrier-delay timer configured on an interface. You can specify a period of time (in seconds) to delay communicating status change of a tracked interface.
You can set a specific amount of time for the router to wait before trying to bring up a NIM interface after the NIM goes down using the serial restart-delay command in the interface configuration mode.
The serial NIM supports the non return to zero inverted (NRZI) line-coding format for signal transitions.NRZI uses relational encoding to interpret signals rather than determining absolute values. You can enable NRZI format using the nrzi-encoding command in the interface configuration mode.
You can enable the data terminal ready (DTR) pulse signal intervals on the serial interfaces using the pulse-time command in interface configuration mode. 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. Setting up the DTR pulse signal intervals is useful for handling encryption or other similar devices that use the toggling of the DTR signal to resynchronize.
When the serial interface is operating in DTE mode, by default, it monitors the Data Carrier Detect (DCD) signal as the line up/down indicator. The attached DCE device sends the DCD signal by default. When the DTE interface detects the DCD signal, it changes the state of the interface to up.
In some configurations, such as an the Synchronous Data Link Control (SDLC) multidrop environment, the DCE device sends the Data Set Ready (DSR) signal instead of the DCD signal, which prevents the interface from coming up. To tell the interface to monitor the DSR signal instead of the DCD signal as the line up/down indicator, configure the ignore dcd command in the interface configuration mode.
You can configure the ignore [cts|dcd|dsr|dtr|rts] command to ignore the incoming signals that may be flapping due to certain cabling issues. When the ignore [cts|dcd|dsr|dtr|rts] command is configured, a signal is automatically seen as asserted.
Systems that use long cables or cables that are not transmitting the TxC (clock) signal might experience high error rates when operating at higher transmission speeds. If a Serial NIM port is reporting a high number of error packets, a phase shift might be the problem; inverting the clock might correct this phase shift.
When the EIA/TIA-232 interface is a DTE, the invert-txclock command inverts the TxC signal the DTE receives from the remote DCE. When the EIA/TIA-232 interface is a DCE, the invert-txclock command inverts the clock signal to the remote DTE port. You can use the no invert-txclock command to change the clock signal back to its original phase.
- Verifying Interface Port Connection
- Verifying the Cisco 1-, 2-, and 4-port Serial NIM Connection Using the loopback Command
- Verifying Using show commands
The ping command sends echo request packets out to a remote device at an IP address that you specify. After sending an echo request, the system waits a specified time for the remote device to reply. Each echo reply is displayed as an exclamation point (!) on the console terminal; each request that is not returned before the specified timeout is displayed as a period (.). A series of exclamation points (!!!!!) indicates a good connection; a series of periods (.....) or the messages [timed out] or [failed] indicate a bad connection.
You can run a loopback test using a loopback command in DCE mode to verify the connection between the peer router and the Serial NIM. When the loopback command is configured on a Cisco 1-port, 2-port, and 4-port Serial HWIC DCE serial port, any incoming data is looped back out on the transmit line. Also, any traffic sent from the Cisco 1-, 2-, and 4-port Serial NIM’s host router is looped back to itself without being processed by the NIM’s serial controller.
NoteOn a Cisco 1-, 2-, and 4-port Serial Network Interface Modules, the looback feature works as intended only when a serial interface is connected to a DCE cable. On a Cisco 1-, 2-, and 4-port Serial Network Interface Modules, the looback feature works as intended only when a serial interface is connected to a DCE cable.
- show version
- show platform
- show interfaces
- show start (start up config)
- show run (running configuration)
Cisco IOS Software, ISR4400 Software (X86_64_LINUX_IOSD-UNIVERSALK9-M), Experimental Version 15.4(20140205:045828) [v154_2_s_xe312_throttle-BLD-BLD_V154_2_S_XE312_THROTTLE_LATEST_20140205_020103-ios 202]
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