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..
One way to deploy IS-IS onto a three-layer hierarchy is to configure the network core as a single L2 routing domain and place the distribution and access layers into various L1 domains, as needed. This design closely mimics an OSPF network with area 0 in the core and the distribution and access layers contained within areas connected to area 0, as Figure 5-3 illustrates. Figure 5-3. Pure D2 Core in Three-Layer Hierarchy The advantages and disadvantages of constraining the..
As if 100 Mbps is not enough, yet another higher bandwidth technology was unleashed on the industry in June of 1998. Gigabit Ethernet (IEEE 802.3z) specifies operations at 1000 Mbps, another tenfold bandwidth improvement. We discussed earlier how stations are hard-pressed to fully utilize 100 Mbps Ethernet. Why then do we need a Gigabit bandwidth technology? Gigabit Ethernet proponents expect to find it as either a backbone technology or as a pipe into very high speed file se..
Challenges Unique to WLAN Management
WLANs present several unique management challenges. Many relate to the physical aspects of the wireless environment, whereas some are the result of the dynamic nature of the wireless network and its mobile users and devices. Knowledge of these challenges will help ensure that you do not overlook these areas in framing your management strategy for the enterprise-class WLAN. Some of the most commonly experienced problems and challenges you will face include the following: •&..
