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..
Using Metrics and Metric Types to Influence Redistributed Routes
A different set of issues can occur for a router that is internal to a single routing domain, like R4and R5 in Figure 11-4. The issue is simple—with multiple redistributing routers, an internal routerlearns multiple routes to the same subnet, so it must pick the best route. As covered earlier in thechapter, the redistributing routers can set the metrics; by setting those metrics with meaningfulvalues, the internal routers can be influenced to use a particular redistribution..
The exchange of data in an 802.11 network is bidirectional between the radio card and access point. As mentioned earlier, data frames in an infrastructure wireless LAN do not travel directly between wireless users. Instead, the access point relays the data. A radio card or access point (802.11 station) having the destination MAC address of the data frame replies with an acknowledgement (ACK) frame. This adds significant overhead to a wireless LAN as compared to an Ethernet n..
Business Priorities Must Come First
A university I once worked with decided it was time to allow the student body and faculty wireless access to the campus network. The convenience of access, cost reduction in wiring buildings, and potential productivity increase were the overarching business drivers for the decision. At first blush, however, the security department was reluctant to proceed. For years, the university did not require students to have accounts to access the network. Rather, authentication was re..
Recall that when an 802.1D switch detects a port state change (either up or down); it signals the root bridge by sending Topology Change Notification (TCN) BPDUs. The root bridge, in turn, must signal the topology change by sending out a TCN message that is relayed to all switches in the STP domain. RSTP detects a topology change only when a nonedge port transitions to the Forwarding state. This might seem odd because a link failure is not used as a trigger. RSTP uses ..
