Configuration and debugging of Cisco Routers

Routers play an important role in computer networks and serve as a bridge between computer networks. It not only connects to different networks, but also selects data transmission paths and blocks illegal access.

Router configuration is not very easy for beginners. We will introduce general configurations and simple debugging of routers for your reference When configuring routers. This article uses cisco2501 as an example.

Cisco2501 has an Ethernet port (AUI), a Console port (RJ45), an Aux port (RJ45), and two synchronous serial ports. It supports DTE and DCE devices, supports EIA/TIA-232, EIA/TIA-449, V.35, X.25, and EIA-530 interfaces.

1. Configuration

1. Configure the Ethernet port

# Conf T (configure the vro from the terminal)

# Int E0 (specified E0 port)

# Ip addr abcd xxxx (ABCD is an ethernet address and XXXX is a subnet mask)

# Ip addr abcd xxxx secondary (E0 port supports two address types at the same time. If the first one is a Class address, the second one is B or C Class address)

# No Shutdown (activate E0 port)

# Exit

After completing the preceding configuration, run the ping command to check whether the E0 port is normal. If the port is not activated, it is often overlooked by beginners. Use the no shutdown command to activate the E0 port.

2. X.25 Configuration

# Conf t

# Int S0 (S0 port specified)

# Ip addr abcd xxxx (ABCD is the IP address of Ethernet S0, and XXXX is the subnet mask)

# Encap X25-ABC (encapsulate X.25 protocol. ABC specifies that X.25 is a DTE or DCE operation. The default value is DTE)

# X25 addr abcd (ABCD is the X.25 port address of S0, provided by the Post Office)

# X25 map ip abcd xxxx Br (mapped X.25 address. ABCD is the IP address of the Peer router (for example, S0) and XXXX is the X.25 port address of the Peer router (for example, S0)

# X25 htc x (configure the maximum number of two-way channels. The value range of X is 1-4095. It must be configured according to the number actually provided by the Post Office)

# X25 nvc x (the number of virtual circuits configured, X cannot exceed the number actually provided by the post office; otherwise, normal data transmission will be affected)

# Exit

After the S0 port is configured, use the no shutdown command to activate the E0 port. If the ping to port S0 is normal, the ping to the mapped X.25 IP address, that is, the IP address of the Peer router port, may be caused by the following situations: 1) Local X.25 address configuration error, check with the Post Office again (the length of X.25 address is 13 characters); 2) the local ing IP address or X.25 address is incorrectly configured, And the configuration is correct; 3) the peer IP address or X.25 address is incorrectly configured; 4) the local or peer route configuration is incorrect.

Can communicate with the other party, but packet loss occurs. In this case, there are generally the following possibilities: 1) Poor line conditions, or poor contact between the NIC and RJ45 plug; 2) the value range of x25 HTC's maximum two-way channel number X and the number of x25nvc virtual circuits x exceed the number actually provided by the post office. The larger the maximum number of two-way channels and the number of virtual circuits, the better, but it must not exceed the number actually provided by the post office. Otherwise, packet loss may occur.

3. leased line configuration

# Conf t

# Ints2 (specifying S2 ports)

# Ip addr abcd xxxx (ABCD is an IP address of S2 and XXXX is a subnet mask)

# Exit

After the leased line port is configured, use the no shutdown command to activate the S2 port.

4. Frame Relay Configuration

# Conf t

# Int S0

# Ip addr abcd xxxx (ABCD is an IP address of S0, and XXXX is a subnet mask)

# Encap frante_relay (encapsulate the frante_relay Protocol)

# No nrzi_encoding (nrzi = No)

# Frame_relay lmi_type q933a (LMIS uses the q933a standard. There are three types of LMIS (Local Management Interface): ANSI: t1.617, ccitty: q933a and Cisco-specific standards)

# Fram-relay INTF-typ ABC (ABC is the frame relay device type, which are supported by DTE devices, DCE switches, or NNI (Network Contact Interfaces)

# Frame_relay interface_dlci 110 Br (configure dlci (data link connection identifier ))

# Frame-relay map ip abcd xxxx broadcast (establishes a frame relay ing. ABCD is the IP address of the other party, XXXX is the local dlci number, and broadcast allows the broadcast to forward or update the route)

# No Shutdown (activate this port)

# Exit

After configuring the S0 port for Frame Relay, run the ping command to check the S0 port. If the port is not activated, use the no shutdown command to activate the S0 port. If the ping to port S0 is normal and the IP address mapped by Ping is abnormal, it may be a frame relay switch or the other party's configuration error. Comprehensive troubleshooting is required.

5. Configure synchronous/asynchronous ports (applicable to 2522)

# Conf t

# Int S2

# PH Asyn (configure S2 as an asynchronous port)

# PH sync (configure S2 as the synchronization port)

6. Dynamic Route Configuration

# Conf t

# Router VPN 20 (using the OSPF routing protocol. Common routing protocols include rip, IGRP, and is-is)

# Passive-interface serial0 (if S0 is connected to X.25, enter this command)

# Passive-interface serial1 (if S1 is connected to X.25, enter this command)

# Network ABCD (ABCD is the local ethernet address)

# Network xxxx (IP address with XXXX being S0)

# No auto-Summary

# Exit

7. Static route Configuration

# IP router abcd xxxx yyyy 90 (ABCD is the ethernet address of the Peer router, XXXX is the subnet mask, and YYYY is the WAN port address of the Peer router)

# Dialer-List 1 Protocol IP permail

Ii. Integrated debugging

After all the vrouters are configured, you can perform a comprehensive debugging.

1. Activate the Ethernet port of the router and all the serial ports to be used. The method is to enter this port and execute no shutdown.

2. Add the default route (the ethernet address of the central router) to the host connected to the router ). Run the following command under a Unix Super User: Router add default XXXX 1 (XXXX is the E0 port address of the router ). Add a default route to each host. Otherwise, communication will fail.

3. Ping the Ethernet port of the local router. If the port fails, the Ethernet port may not be activated or is not in the same network segment. Ping the wide area network port. If the port fails, no default route is added. Ping the WAN port of the other Party. If no connection is available, the router configuration is incorrect. Ping the Ethernet port of the host. If the port fails, no default route is added to the host.

4. Add a gateway (static route) to the host X.25 of the leased line card ). The method is to execute: Router add X. x. x. X y.y. y.y 1 (X. x. x. X is the peer ethernet address, y.y. y.y is the WAN address of the other party ).

5. Use tracert to track the route to determine the CIDR block.