Designated Routers on WANs and OSPF Network Types
Using a DR makes good sense on a LAN because it improves LSA flooding efficiency. Likewise, not using a DR on a point-to-point WAN link also makes sense, because with only two routers on the subnet, there is no inefficiency upon which to improve. However, on nonbroadcast multiaccess (NBMA) networks, arguments can be made regarding whether a DR is helpful. So, OSPF includes several options that include a choice of whether to use a DR on WAN interfaces. Cisco router interfaces..
VMPS and Dynamic VLANs: Advanced Administration
Normally, when you configure a VLAN, you must perform three steps: 1. Ensure that the Catalyst belongs to a VTP domain 2. Create a VLAN 3. Assign ports to the VLAN The first two steps globally affect Catalysts. When you create a VLAN, VTP announces the addition or deletion of the VLAN throughout the VTP domain. Assigning ports to a VLAN, however, is a local event. VTP does not announce what ports belong to which VLAN. Yo..
Using Spanning Tree in Real-World Networks
Look at Figure 6-20 for a more complex topology, and see how all this STP detail adds up in the real world. Figure 6-20. A Complex Network with All Links Shown Figure 6-20 illustrates a network of seven switches connected in a highly redundant (that is, looped) configuration. Link costs are indicated—all are Fast Ethernet (cost of 19) except for the vertical link on the far left that is 10BaseT (cost of 100). Assuming that Cat-4 wins the Root War, F..
Configuring CBWFQ for Frame Relay
This section discusses the configuration tasks for enabling CBWFQ on Frame Relay PVCs. CBWFQ is configured via the MQC configuration interface; MQC was explained at the beginning of this chapter. Table 18-1 lists the configuration options available for setting up the traffic classes. Table 18-2 displays the class policy configurations available. Table 18-1. Available Options for Setting Up the Traffic Class (class-map) Command (config-cmap) ..
Cisco provides a useful option called eBGP Multihop, which allows you to establish eBGP peer relationships between routers that aren't directly connected to one another: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#ip route 172.20.1.2 255.255.255.255 192.168.1.5 2 Router1(config)#router bgp 65500 Router1(config-router)#neighbor 172.20.1.2 remote-as 65530 Router1(config-router)#neighbor 172.20.1.2 update-source ..
