To check host reachability and network connectivity, use the ping Privileged EXEC command. The extended ping and extended traceroute utilities are called by entering the commands without any destination. This results in the utilities asking a series of questions, allowing you to change the defaults.
Configuring AppleTalk Filtering via Access Lists
The packet-filtering facilities for AppleTalk in the Cisco IOS software enable a network administrator to restrict access to certain AppleTalk resources—including individual servers, printers, network segments, ranges of addresses, and entire zones—based on a variety of criteria. Like access list configuration for TCP/IP, the packet-filtering process consists of defining the filtering criteria and then applying the criteria to specific AppleTalk interfaces. Defining Acce..
Standards Bodies and Incident Response Teams
Numerous standards bodies today help a network administrator design a sound security policy. The two main entities that are helpful are the Computer Emergency Response Team Coordination Center (CERT/CC) and the various newsgroups that enable you to share valuable security information with other network administrators. CERT/CC is a U.S. federally-funded research and development center at Carnegie Mellon University in Pittsburgh, Pennsylvania. Following the infamous worm incid..
Using BPDU Filtering to Disable STP on a Port
Ordinarily, STP operates on all switch ports in an effort to eliminate bridging loops before they can form. BPDUs are sent on all switch ports—even ports where PortFast has been enabled. BPDUs also can be received and processed if any are sent by neighboring switches. You always should allow STP to run on a switch to prevent loops. However, in special cases when you need to prevent BPDUs from being sent or processed on one or more switch ports, you can use BPDU filte..
Verifying Frame Relay Connections with IOS show Commands
Many Cisco IOS commands that are supported on Cisco routers can be used either to validate users' Frame Relay configuration command changes, to verify the status of the Frame Relay connection, or as a troubleshooting tool. For instance, the show frame-relay map command displays the remote network address to local DLCI mapping and indicates the remote network destinations reachable via the connected Frame Relay network. This section looks at the general IOS show commands most ..
