IEEE 802.1w Rapid Spanning Tree Protocol (RSTP) enhances the 802.1D standard with one goal in mind: improving STP convergence. To do so, RSTP defines new variations on BPDUs between switches, new port states, and new port roles, all with the capability to operate backwardly compatible with 802.1D switches. The key components of speeding convergence with 802.1w are as follows: ■ Waiting for only three missed Hellos on an RP before reacting (versus ten missed Hellos via the ..
In most cases, an access router serves a large number of customers. With modern access technology, this number can reach the thousands. As a result, resilient connectivity to the distribution routers is recommended. This may be accomplished using a self-healing LAN technology, such as FDDI. Alternatively, as with the connectivity between distribution and backbone routes, this may involve the use of redundant LAN switches. If the access router is the only node in a small POP, ..
Distribution/Regional Network Design
The role of the regional network is to route intra- and inter-regional traffic. The regional network generally is comprised of a DC as the hub and a number of access POPs as the spokes. Usually, two redundant routers in each regional network will connect to the backbone. DCs may also provide services such as Web-caching, DNS, network management, and e-mail hosting. In some cases, the latter functionality may be extended into major POPs. Placement o..
When you configure a router's serial interface, you need to specify the encapsulation, the IP address, and whether the interface will be the DCE or DTE: Router3#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router3(config)#interface Serial1 Router3(config-if)#description WAN Connection to Chicago Router3(config-if)#ip address 192.168.99.5 255.255.255.252 Router3(config-if)#encapsulation hdlc Router3(config-if)#clock rate 56000 Router3..
By default, Cisco routers will listen for both RIP Version 1 and 2 packets, but they will only send Version 1. If you want to configure the router to send and receive only Version 2 RIP packets, use the version 2 configuration command: Router2#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router2(config)#router rip Router2(config-router)#version 2 Router2(config-router)#network 172.25.0.0 Router2(config-router)#network 192.168.30.0 Rou..
