IPv6 addresses have eight quartets of hex digits, separated by colons. Each quartet consists of four hex digits, which together represent 16 bits. The rules for encoding the actual hex values are as follows: ■ Each quartet is separated by a colon (:). ■ In a quartet, leading hex 0s can optionally be omitted. ■ If one or more consecutive quartets are hex 0000, then the set of consecutive all-0 quartets can be represented as a null quartet (::), no matter how many cons..
It is debatable whether OSI or IPX represented the most serious contender to TCP/IP as the ubiquitous networking technology of the future. At one time, IPX enjoyed an installed base that far exceeded IP, and numerous plans arose to build the IPX equivalent of the Internet. Novell NetWare (see Figure 1-12) is based upon a client-server paradigm, with the initial intent of sharing large disk volumes among a set of relatively meagerly equipped clients. As with Appl..
DoS/Worm-Mitigation Strategies
A proactive approach to mitigating DoS/worm flooding attacks within campus environments is to respond immediately to out-of-profile network behavior that indicates a DoS or worm attack using access-layer policers. Such policers could meter traffic rates received from endpoint devices, and when these exceed specified watermarks (at which point they no longer are considered normal flows), these policers could mark down excess traffic. In this respect, the policers would be fai..
Starting with IOS Version 12.4(2)T, Cisco introduced support for stronger encryption capabilities. To enable 3DES use the following command: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#snmp-server user wbrejniak ORAROV3 v3 auth md5 authpass priv 3des privpass Router1(config)#end &n..
Use the NTP and clock show commands to verify the status of NTP on your router. The best place to start is the show clock detail command, which provides information on the current time, time source, and time zone configuration: Router>show clock detail 15:54:33.079 EST Sun Jan 29 2006 Time source is NTP Summer time starts 02:00:00 EST Sun Apr 2 2006 Summer time ends 02:00:00 EDT Sun Oct 29 2006 Router> To display the current NTP status of the local router, the comman..
