This section discusses MPLS operation over interfaces where labeled packets are sent encapsulated in Layer 2 frames (Frame-mode MPLS operation). Label Switch Routers (LSRs) use Label Distribution Protocol (LDP, an IETF standard) or Tag Distribution Protocol (TDP, a Cisco pre-standard) to exchange IP prefix-to-label bindings. A Label Information Base (LIB, also called a Tag Information Base [TIB]) stores these bindings, which are used to build the Forwarding Information Base ..
Defining the Router ID and Loopback Interfaces
The router needs an ID to participate in the OSPF domain. The router ID is used to identify LSAs in the OSPF database. The router ID can be defined by an administrator or left to the discretion of the router. Most people define the ID so that it is easier to track events in the network, for internal documentation, and for other system-administration purposes. The OSPF router ID can be defined by the router-id command. If the router-id command is not present, then the ..
Maintaining Syslog Files on the Server
The Bourne shell script in Example 18-1 automatically rotates router logfiles to ensure that these files don't become too big and cumbersome to navigate. The script is intended to be invoked via a cron job on a daily basis, but you can also run it manually. By default, the script retains seven days worth of archived logfiles and compresses files older than two days. No arguments are required or expected. Example 18-1. rotatelog.sh #!/bin/sh # # rotatelog.sh -- a ..
Like most high-end routing protocols, EIGRP supports variable-length subnet masking (VLSM), and advertisements are sent via multicast (that is, to an address of 224.0.0.10). By default, EIGRP automatically performs route summarization. This could be an issue for a topology containing discontiguous subnets of the same major classful network. To turn off automatic summarization, you can issue the no auto-summary command in router configuration mode for an EIGRP autonomous syst..
Enabling Frame Relay Encapsulation
On a Cisco router, Frame Relay can be configured only on the supported interfaces; it's most commonly supported on synchronous serial interfaces. A single Cisco IOS command is all that is required to enable Frame Relay on the serial interface. The encapsulation frame-relay interface configuration command, as follows, is used to enable Frame Relay encapsulation and to allow Frame Relay processing on the supported interface. R1(config)#interface serial4/2 R1(config-if)#encapsu..
