Configuration Options for an Internal Router
The following options allow you to tune the OSPF configuration of an internal router: • Router ID • Loopback interface • cost command • priority command
PIM-DM: Reacting to a Failed Link
When links fail, or any other changes affect the unicast IP routing table, PIM-DM needs to update the RPF interfaces based on the new unicast IP routing table. Because the RPF interface may change, (S,G) entries may also need to list different interfaces in the outgoing interface list. This section describes an example of how PIM-DM reacts. Figure 20-7 shows an example in which the link between R1 and R3, originally illustrated in Figure 20-6, has failed. After the unicast ro..
Setting the IP Source Address for Syslog Messages
Use the logging source-interface configuration command to specify a particular IP address for syslog messages: Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#logging host 172.25.1.1 Router(config)#logging source-interface Loopback0 Router(config)#end Router# Normally, when you enable logging to a remote server, that server will see the source of the message as being the router's nearest interface. However, this is..
Compressing Frame Relay Data on a Subinterface
Cisco offers several different types of compression with Frame Relay. You can opt to compress only the TCP headers as follows: Central#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Central(config)#interface Serial0 Central(config-if)#encapsulation frame-relay Central(config-if)#frame-relay ip tcp header-compression passive Central(config-if)#exit Central(config)#end Central# This command also works at the subinterface level: Central#..
Sometimes you need to connect your network to another network that uses an unregistered range, such as 172.16.0.0/16. However, if you already use this range in your network, the easiest thing to do is to simply replace this prefix with another one that doesn't have a conflict, such as 172.17.0.0/16: Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#ip nat outside source static network 172.16.0.0 172.17.0.0 /16 no-al..
