The show isis spf-log command explains a great deal about the SPF calculations on the router. It reveals the events that triggered SPF for the last 20 occurrences. To display how often, and why, the router has run a full SPF calculation, use the show isis spf-log EXEC command. Example 10-13 shows output for the show isis spf-log command. The example shows that Router A sent an LSP because it had set the ATT bit, and later it generated a new LSP when new adjacenc..
All EIGRP routers periodically announce themselves with the Hello protocol using a multicast address of 224.0.0.10. On hearing Hellos, the receiving routers add an entry in their neighbor table. The continued receipt of these packets maintains the neighbor table. If a Hello from a known neighbor is not heard within the holdtime, the neighbor is treated as no longer operational and removed from the table. The holdtime, by default, is three times the Hello timer. Therefore, if ..
Steady-State Operation by Continuing to Send Joins
To maintain the forwarding state of interfaces, PIM-SM routers must send PIM Join messages periodically. If a router fails to send Joins periodically, PIM-SM moves interfaces back to a pruned state. PIM-SM routers choose to maintain the forwarding state on links based on two general criteria: ■ A downstream router continues to send PIM joins for the group. ■ A locally connected host still responds to IGMP Query messages with IGMP Report messages for the group. Figure 20..
The Cisco PIX and ASA VPN capabilities have their roots in Cisco IOS VPN technologies. VPNs were first introduced in the Cisco IOS router product line and then added to the PIXs in an early 5.x release. Like the routers and the concentrators, Cisco PIXs support many VPN solutions including IPsec, PPTP, and L2TP. Because of their flexibility, they can be used in many different situations. The ASA was introduced in the spring of 2005. The ASA is a unique hybrid security applian..
The current VTP parameters for a management domain can be displayed using the show vtp status command. Example 5-1 demonstrates some sample output of this command from a switch acting as a VTP client in the VTP domain called CampusDomain. VTP message and error counters also can be displayed with the show vtp counters command. You can use this command for basic VTP troubleshooting to see whether the switch is interacting with other VTP nodes in the domain. Example 5-2 d..
