Vro configuration and debugging

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. Take 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 router from the terminal)
# Int e0 specified E0 port)
# Ip addr abcd xxxxabcd is the ethernet address, and XXXX is the subnet mask)
# The ip addr abcd xxxx secondaryE0 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 to activate E0 ports)
# 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 specified S0 port)
# Ip addr abcd xxxxabcd is the ip address of the Ethernet S0, and XXXX is the subnet mask)
# The encap X25-ABC encapsulates the X.25 protocol. ABC specifies that X.25 is a DTE or DCE operation. The default value is DTE)
# X25 addr ABCDABCD is the X.25 port address of S0, provided by the Post Office)
# X.25 address mapped by x25 map ip abcd xxxx br. ABCD is the IP address of the Peer router such as S0), XXXX is the X.25 address of the Peer router such as S0)
# X25 the maximum number of two-way channels configured for htc X. 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, ping the mapped X.25 IP address, that is, the IP address of the Peer router port, may be caused by the following situations:

1) The local X.25 address is incorrectly configured. Check with the post office that the X.25 address is 13 characters long );

2) The local ing IP address or X.25 address is incorrectly configured. 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 with NICs and RJ45 plugs;

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
# Int S2 specifying S2 port)
# Ip addr abcd xxxxabcd is the ip address of S2, and XXXX is the 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 using the Q933A standard. LMILocal management Interface) There are three types: ANSI: T1.617, CCITTY: Q933A and Cisco-specific standards)
# Fram-relay intf-typ ABCABC is supported by DTE devices, DCE switches, and NNI Network Contact Interfaces)
# Frame_relay interface_dlci 110 br configure the 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 to 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 for 2522)
# Conf t
# Int s2
# Configure S2 as an asynchronous port for ph asyn)
# Configure S2 as the synchronization port for ph sync)
6. Dynamic Route Configuration
# Conf t
# Router VPN 20 uses 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 is the local ethernet address)
# Network xxxx ip address with S0)

# No auto-summary
# Exit
7. Static route Configuration
# Ip router & nb ????? Sp; 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 ethernet address of the default route center router to the host connected to the router ). Run "router add default XXXX 1XXXX" as the E0 port address of the router under the super user of the Unix system ). 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 static gateway route to the host X.25 ). The method is to execute: router add X. x. x. X Y.Y. y.Y 1X. 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.