There are downsides to multicasting that must be recognized. Because multicast traffic is generally UDP it lacks windowing functions, packet ordering, and capability for retransmission. It also lacks the ability to allow some users to receive multicasts while preventing others on the segment (although there are ways to block multicasts at the router). These challenges can be met creatively at the protocol level. For multimedia traffic, ordering is handled by the..
Aggregatable Global Unicast Addresses
IPv6 defines several different types of unicast addresses. The format used for publicly registered addresses is called aggregatable global unicast. The term aggregatable refers to fact that these addresses can be easily aggregated to reduce the problem of large Internet routing tables. The term global refers to the fact that the address is a registered public IP address, routable through the global Internet. In short, when a company obtains a registered IPv6 prefix from a Reg..
Wireless Domain Services (WDS) is a set of Cisco IOS Software features that enhances and simplifies wireless LAN client mobility, security, deployment, and management. WDS offers the following primary services for SWAN: ■ Fast Secure Roaming (FSR)—For time-sensitive applications, enables a wireless client to securely roam between access points in the same subnet or between subnets, enhances channel scanning, and provides fast IEEE 802.1X rekeying. Access point handoff ti..
In order to modify system log messages, you must configure the Embedded Syslog Manager (ESM) by using a combination of configuration commands and TCL scripts. First you must write a TCL script to perform a certain task and make it available via TFTP. In this simple example, the TCL script in Example 18-3 filters out a particular system log message (clear counters) and permits all other messages to be forwarded as normal. Example 18-3. delcounters.tcl # delcounters.tcl ..
Configuring DLCI Priority Levels
DLCI priority level is a legacy traffic management tool that allows users to prioritize multiple parallel Frame Relay DLCIs based on the types of Frame Relay traffic that are carried. DLCI priority level can be used to alleviate congestion for certain types of traffic by allowing users to define different DLCIs for different categories of traffic based on traffic priorities. For example, DLCI priority level is useful in situations in which delay-sensitive traffic is mixed wit..
