Required Commands for Configuring OSPF Within a Single Area

In this section, you learn to configure an internal OSPF router. An internal router is one in which all interfaces lie within a single area. The sole OSPF function of an internal router is to route within the area.   The router needs to understand how to participate in the OSPF network, as defined by the following parameters:  • OSPF process— Declare an OSPF process.  • Participating interfaces— Identify the interfaces to be used by OSPF. ..

Label Imposition at the Network Edge

Label imposition has been described already as the act of prepending a label to a packet as it enters the MPLS domain. This is an edge function, which means that packets are labeled before they are forwarded to the MPLS domain. To perform this function, an Edge-LSR needs to understand where the packet is headed and which label, or stack of labels, it should assign to the packet. In conventional Layer 3 IP forwarding, each hop in the network performs a lookup in the IP forwar..

Circuit-Switched Networks

Packet-switched networks fundamentally differ from circuit-switched networks. As shown in Figure 3-2, a connection must first be established between two end hosts in order for them to communicate in a circuit-switched network. This can be achieved by i n-band signaling (call_setup) within a circuit—in other words, the end host transmits a set of signals that allows the circuit to be extended, hop-by-hop, through the network. Alternatively, as in the case of the Integrated S..

Forming an OSPF Adjacency

Although two OSPF routers can form an adjacency (that is, become neighbors) through the exchange of Hello packets, the following parameters in the Hello packets must match: ■ Hello timer: This timer defaults to 10 seconds for broadcast and point-to-point networ types. The default is 30 seconds for nonbroadcast and point-to-multipoint networ types. ■ Dead timer: This timer defaults to 40 seconds for broadcast and point-to-point networ types. The default is 120 seconds fo..

Using Multipoint Subinterfaces

You can connect several virtual circuits to a single subinterface as follows: Central#configure terminal Enter configuration commands, one per line.  End with CNTL/Z. Central(config)#interface Serial0.1 multipoint Central(config-subif)#description Frame Relay to branches Central(config-subif)#ip address 192.168.1.1 255.255.255.0 Central(config-subif)#frame-relay interface-dlci 101 Central(config-subif)#frame-relay interface-dlci 102 Central(config-subif)#frame-relay int..