Multicast routing is not supported on Cisco routers by default. Use the following command to enable multicast routing in global configuration mode: Router(config)#ip multicast-routing
The ARP and proxy ARP processes both occur after a host knows its IP address and subnet mask. RARP, BOOTP, and DHCP represent the evolution of protocols defined to help a host dynamically learn its IP address. All three protocols require the client host to send a broadcast to begin discovery, and all three rely on a server to hear the request and supply an IP address to the client. Figure 5-4 shows the basic processes with RARP and BOOTP. Figure 5-4 RARP and BOOTP—Basic P..
NSSA is similar to the OSPF stub area, but it has the capability to import AS external routes in a limited capacity within the NSSA area. NSSA allows importing type 7 LSAs within the NSSA area by redistribution and then converts them into type 5 at the ABR. This enables the administrator to summarize and filter data at both ASBR and ABR levels.
With the introduction of the Versatile Interface Processor (VIP) cards, Cisco made the ultimate step toward a peer multiprocessor architecture. Each VIP card contains its own MIPS r4600 RISC processor, runs a mini-IOS kernel, and has configurable levels of SRAM and DRAM. Although the VIP1 was available for a short time, most of the installed base consists of VIP2s. The distributed features are targeted at the 7500 series (see Figure 5-6), but a VIP1 without distributed featur..
Preventing Loops with Spanning Tree Protocol
Bridging loops form because parallel switches (or bridges) are unaware of each other. STP was developed to overcome the possibility of bridging loops so that redundant switches and switch paths could be used for their benefits. Basically, the protocol enables switches to become aware of each other so they can negotiate a loop-free path through the network. Note: Because STP is involved in loop detection, many people refer to the catastrophic loops as “spanning-tree lo..
