Using traceroute and Extended ping
You can use traceroute to determine the path taken, as well as to identify where there is a problem in the network. Where the traceroute utility fails indicates a good starting point for troubleshooting a complex network. The extended ping command is very useful in that it announces every interface that it traverses if the record option is selected. The nine hop maximum of the record route option for extended ping is a real limitation, though. It is also possi..
General Layer 2 Security Recommendations
Recall that the beginning of the “Layer 2 Security” section outlined the Cisco SAFE Blueprint recommendations for user and unused ports and some general recommendations. The general recommendations include configuring VTP authentication globally on each switch, putting unused switch ports in an unused VLAN, and simply not using VLAN 1. The underlying configuration for each of these general recommendations is covered in Chapter 2. Additionally, Cisco recommends not using t..
Basic Single Area IS-IS Configuration
This section examines the process of configuring a single IS-IS area using the network in Figure 7-11. Figure 7-11. Single Area IS-IS Network [View full size image] The steps for a basic single area IS-IS configuration are as follows: Step 1. Configure a loopback interface on each OSPF router. Step 2. Configure IP addresses on the physical interfaces. Step 3. Configure the IS-IS process on each router. Step 4. Enable IS-IS on the router interfaces. The loopback addresses, ..
Understanding the Detrimental Effects of LDP Restart
At this point, the discussion turns to the issues that arise when the LDP control-plane component of an LSR restarts. As described earlier, an LDP session is established over TCP. When an LDP control-plane component on an LSR restarts, the restarting LSR (on which the control plane has restarted) loses LDP sessions with its LDP peers. RFC 3036 requires that whenever the TCP connection supporting an LDP session fails, LDP must immediately release all FEC-to-label mappings, inc..
Viewing DLSw Status Information
This command shows the status of a DLSw peer relationship: Router>show dlsw peers Peers: state pkts_rx pkts_tx type drops ckts TCP uptime TCP 10.1.1.5 CONNECT 350 350 conf ..
