AS_PATH Prepending and Route Aggregation
The concept and motivation behind the AS_PATH prepend feature is simple—impact the AS_PATH length decision step by increasing the length of the AS_PATH. To do so, a router simply configures a route map, refers to it with a neighbor route-map command, with the route map using the set as-path prepend asn1 asn2… command. As a result, the route map prepends additional ASNs to the AS_SEQUENCE. Any ASN can be prepended, but in practice, it makes the most sense to prepend the lo..
Label Switching in Frame-Mode MPLS
After receiving the Layer 2 PPP frame from the San Jose router, the San Francisco router immediately identifies the received packet as a labeled packet based on its PPP Protocol field value and performs a label lookup in its Label Forwarding Information Base (LFIB). NOTE LFIB also is called Tag Forwarding Information Base (TFIB) in older Cisco documentation.The LFIB entry corresponding to inbound label 30 (and displayed in Example C-2) directs the San Francisco router to rep..
Use the following command to send router log messages to a remote syslog server: Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#logging 172.25.1.1 Router(config)#end Router# Although configuring the router with a static IP address like this is the preferred method of configuring a syslog server, you can also specify a hostname to be resolved: Router#configure terminal Enter configuration commands, one per line.&n..
Using Frame-Relay Traffic Shaping
This first example shows how to configure frame relay traffic shaping by using point-to-point frame relay subinterfaces: Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#interface HSSI0/0 Router(config-if)#encapsulation frame-relay Router(config-if)#exit Router(config)#interface HSSI0/0.1 point-to-point Router(config-subif)#traffic-shape rate 150000 Router(config-subif)#frame-relay interface-dlci 31 Router(config-sub..
Automatically Configuring STP Timers
Modifying STP timers can be tricky, given the conservative nature of the default values and the calculations needed to derive proper STP operation. Timer values are basically dependent on the Hello Time and the switched network’s diameter, in terms of switch hops. Catalyst switches offer a single command that can change the timer values in a more controlled fashion. As described earlier, the spanning-tree vlan vlan-list root macro command is a better tool to use than setti..
