Depending on the method used to inject a route into a local BGP table, BGP assigns one of three BGP ORIGIN PA codes: IGP, EGP, or incomplete. The ORIGIN PA provides a general descriptor as to how a particular NLRI was first injected into a router’s BGP table. The show ip bgp command includes the three possible values in the legend at the top of the command output, listing the actual ORIGIN code for each BGP route at the far right of each output line. Table 12-7 lists the th..
Label Imposition at the Network Edge
Label imposition has been described already as the act of prepending a label to a packet as it enters the MPLS domain. This is an edge function, which means that packets are labeled before they are forwarded to the MPLS domain. To perform this function, an Edge-LSR needs to understand where the packet is headed and which label, or stack of labels, it should assign to the packet. In conventional Layer 3 IP forwarding, each hop in the network performs a lookup in the IP forwar..
In 1985, the U.S. FCC adopted regulations that specify the availability of license-free frequency bands in the 900-MHz, 2.4-GHz, and 5-GHz portions of the frequency spectrum. To be compliant with the rules for these bands, however, equipment must use spread spectrum or OFDM methods to spread the signal power over a relatively wide portion of the frequency spectrum. This approach promotes frequency reuse—otherwise known as sharing—of these bands by multiple users, with a l..
As discussed in Chapter 4, "Network Topology and Design," accounting of data traffic is not only important for customer billing, but is a crucial part of traffic engineering. For example, knowing the relative size of flows between routers in the network core can help you calculate the most cost-effective topology and circuit size of the core network. In terms of operation, Netflow switching is similar to the fast-switching cache: The first packet of any fl..
Using an Internal ISDN PRI Module
You can configure an ISDN PRI controller module by using the controller T1 command set as follows: Router8#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router8(config)#isdn switch-type primary-dms100 Router8(config)#controller T1 0 Router8(config-controlle)#framing esf Router8(config-controlle)#clock source line primary Router8(config-controlle)#linecode b8zs Router8(config-controlle)#pri-group timeslots 1-24 Router8(config-controlle)..
