The well-known mandatory BGP ORIGIN PA characterizes a route based on how it was injected into BGP. The ORIGIN is either IGP (i), EGP (e), or incomplete (?). The actual BGP decision process for the ORIGIN code is quite simple. First, an ORIGIN of EGP (e) should not occur today, because EGP is not even supported in current IOS revisions. So, the logic reduces to the following: If the set of routes to reach a single NLRI includes only one route of ORIGIN code IGP (i), and all t..
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..
Updating the Routing Table in Passive Mode with DUAL
When a path is lost, DUAL first looks in the topology table for a feasible successor. If one is found, the router stays in passive mode (passive, in this sense, means that the router is not actively querying for an alternative path). Figure 3-5 provides an example network. Figure 3-5. The Use of Feasible and Advertised Distance—Passive Mode The following list explains Figure 3-5 with the metrics and actions that EIGRP takes in determining the path..
Underlying Mechanics of Shaping
Shapers apply a simple formula to the Tc, Bc, and shaping rate parameters: Tc = Bc/shaping rate For example, in Figures 16-1 and 16-2, if the shaping rate (64 kbps) and the Bc (8000 bits) were both configured, the shaper would then calculate the Tc as 8000/64,000 = 0.125 seconds. Alternatively, if the rate and Tc had been configured, the shaper would have calculated Bc as Bc =rate * Tc (a simple derivation of the formula listed earlier), or 64 kbps * 0.125 ms = 8000 bits. ..
You can configure a router to bridge between two or more interfaces, as follows: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#bridge 1 protocol ieee Router1(config)#interface Ethernet0/0 Router1(config-if)#bridge-group 1 Router1(config-if)#exit Router1(config)#interface Ethernet0/1 Router1(config-if)#bridge-group 1 Router1(config-if)#exit Router1(config)#end With Integrated Routing and Bridging (IRB), you can a..
