Integrated Services Digital Network (ISDN) is used by telephone companies to carry digitized voice and data over the existing telephone system. ISDN has emerged as one of the leading technologies for telecommuting and remote office connection into the corporate headquarters. On the seven layer model, ISDN operates at the physical, data link, and network layers. ISDN basic rate interface (BRI) provides two barrier channels (commonly referred as B channels). Each of these B ch..
A campus network’s core layer provides connectivity of all distribution-layer devices. The core, sometimes referred to as the backbone, must be capable of switching traffic as efficiently as possible. Core devices, sometimes called campus backbone switches, should have the following attributes: ■ Very high throughput at Layer 3 ■ No costly or unnecessary packet manipulations (access lists, packet filtering) ■ Redundancy and resilience for high availability ■ Advanc..
Exchanging Multicast Routing Information with MBGP
Before setting up MBGP, you should set up multicast-routing on the Autonomous System Boundary Router (ASBR) and configure it to block multicast traffic that you know is only intended for the local network: Router-ASBR1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router-ASBR1(config)#ip multicast-routing Router-ASBR1(config)#access-list 15 deny 239.0.0.0 0.255.255.255 Router-ASBR1(config)#access-list 15 deny 224.0.1.39 Router-AS..
You can use the offset-list configuration command to modify the metrics of routes that EIGRP learns through a particular interface: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z.Router1(config)#access-list 22 permit 192.168.30.0Router1(config)#router eigrp 55Router1(config-router)#offset-list 22 in 10000 Serial0.1Router1(config-router)#exitRouter1(config)#endRouter1# This command can also modify the EIGRP metrics of routes as the..
UplinkFast: Access-Layer Uplinks
Consider an access-layer switch that has redundant uplink connections to two distribution- layer switches. Normally, one uplink would be in the Forwarding state and the other would be in the Blocking state. If the primary uplink went down, up to 50 seconds could elapse before the redundant uplink could be used. The UplinkFast feature on Catalyst switches enables leaf-node switches or switches at the ends of the spanning-tree branches to have a functioning root port whil..
