Determining the Contents of Updates
A router builds the contents of its Update messages based on the contents of its BGP table. However, the router must choose which subset of its BGP table entries to advertise to each neighbor, with the set likely varying from neighbor to neighbor. Table 12-8 summarizes the rules about which routes BGP does not include in routing updates to each neighbor; each rule is described more fully following the table. Table 12-8 Summary of Rules Regarding Which Routes BGP Does Not Inc..
Orthogonal Frequency Division Multiplexing
OFDM is not a form of spread spectrum. Instead, OFDM divides a data signal across 48 separate subcarriers within a 20-MHz channel to provide transmissions of 6, 9, 12, 18, 24, 36, 48, or 54 Mbps. Data rates of 6 Mbps, 12 Mbps, and 24 Mbps are mandatory for all 802.11-compliant products. OFDM is extremely efficient, which enables it to provide the higher data rates. In addition, OFDM is highly immune to multipath propagation problems that cause significant performance issues w..
An obvious improvement to the single CPU design is the introduction of more independent processing power. One way to achieve this is to connect clusters of routers by using conventional LAN technology and routing protocols. Each router in the cluster is required to perform only switching and route-calculations within the bounds of a single-CPU router design. This approach is similar to that used in parallel processing supercomputers. Unfortunately, even with mod..
Cisco security and IDS provide a mechanism to detect when an intrusion has occurred. The only problem in an HIDS is that a lot of alarms are false positives, especially in a large installation base of CSA clients. In other words, many alarms need not cause your security team to investigate a normal IP packet or TCP segment, for example. A CCIE candidate, however, must be able to tune out normal IP packets and TCP segments in the CCIE lab portion of this certification. The mai..
As seen in Table 5-5, duplex mismatches can cause a wide variety of port errors. Keep in mind that almost all network devices, other than shared media hubs, can run in full-duplex mode. Therefore, if you have no hubs in your network, all devices should be running in full-duplex mode. A new recommendation from Cisco is that switch ports be configured to autonegotiate both speed and duplex. Two justifications for this recommendation are as follows: ■ If a connected device ..
