Prefer Neighbor Type eBGP over iBGP
This step is rather simple, and needs very little elucidation. Keeping in mind that the goal is a single best route for each NLRI, this decision point simply looks to see if a single eBGP route exists. If so, that route is chosen. If multiple eBGP routes exists, this decision point cannot determine the best route. Interestingly, BGP uses this decision point frequently when two or more enterprise routers connect to the same ISP. Each border BGP router in the enterprise receive..
The cost metric is calculated as 100,000,000 bps divided by the bandwidth of the interface in bits per second. Sometimes—especially when dealing with faster lines or other vendor routers that use a different cost—it is useful to change this default value. The cost command manually overrides the default: Router(config-if)# ip ospf cost cost Cost is a 16-bit value (0 to 65,535) and lower values are preferred. Table 5-4 shows examples of default costs. Table 5-..
Packet-Switching Links: Frame Relay
Frame Relay was initially developed by the American National Standards Institute (ANSI) in 1984. Cisco Systems undertook major redevelopment of Frame Relay in 1990. StrataCom (now part of Cisco Systems), Northern Telecom, and Digital Equipment Corporation formed a consortium to focus on the development of Frame Relay technology. This consortium developed some additional features for the internetworking environment. Frame Relay is a packet-switching technology th..
SDLC is a serial protocol that is commonly used for SNA devices. It is extremely popular in financial environments for devices such as banking machines, card readers, and account printers. Using SDLC in conjunction with DLSw is becoming increasingly common in these sorts of situations. This allows the remote SDLC devices to communicate with the Token Ring Interface Coupler (TIC) on a mainframe computer through an IP network. There is a huge advantage to this because it means ..
Simulating a Frame Relay Cloud
A Cisco router can function as a Frame Relay switch. This is mostly useful when you are trying to simulate a Frame Relay cloud in a lab to test your router configurations: Cloud#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Cloud(config)#frame-relay switching Cloud(config)#interface Serial0 Cloud(config-if)#description Frame-relay connection to Central - DLCI 50 Cloud(config-if)#encapsulation frame-relay Cloud(config-if)#clock rate 125..
