Potential Problems With Redistribution
Redistribution is not optimal. The simpler and more straightforward the design, the better managed and more stable the network, which means fewer errors and faster convergence. A hierarchical IP addressing scheme designed to allow continued network growth, combined with a single IP routing protocol that has the scope to support growth, results in a strong, reliable, and fast network. However, it is rare to find a network of any size that runs only one IP routing protocol. Whe..
Dynamically Finding RPs and Using Redundant RPs
In a PIM-SM network, every router must somehow learn the IP address of an RP. A PIM-SM router can use one of the following three methods to learn the IP address of an RP: ■ The RP address can be statically configured on all the PIM-SM routers with the Cisco IOS global command ip pim rp-address address. This is the method used for the five-router topology shown in Figure 20-19. ■ The Cisco-proprietary Auto-RP protocol can be used to designate the RP and advertise its IP ..
Steady-State Operation and the State Refresh Message
As mentioned briefly earlier in the chapter, with PIM-DM, an interface stays pruned only for 3 minutes by default. Prune messages list a particular source and group (in other words, a particular (S,G) SPT). Whenever a router receives a Prune message, it finds the matching (S,G) SPT entry and marks the interface on which the Prune message was received as “pruned.” However, it also sets a Prune timer, default 3 minutes, so that after 3 minutes, the interface is placed into ..
If a switch does not seem to be receiving updated information from a VTP server, consider these possible causes: ■ The switch is configured for VTP transparent mode. In this mode, incoming VTP advertisements are not processed; they are relayed only to other switches in the domain. ■ If the switch is configured as a VTP client, there might not be another switch functioning as a VTP server. In this case, configure the local switch to become a VTP server itself. ■ T..
DHCP-Secured IP Address Assignment
To enable secured IP address assignment, use the update arp command:Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z.Router1(config)#ip dhcp pool OREILLYRouter1(dhcp-config)#update arpRouter1(dhcp-config)#endRouter1#Beginning with IOS Version 12.2(15)T, Cisco introduced the concept of DHCP secured IP address assignment. This feature synchronizes the ARP entry to the DHCP binding to ensure that IP addresses assign via DHCP can'..
