In July 2001, a group called IEEE 802.3ah Ethernet in the First Mile Task Force (http:// grouper.ieee.org/groups/802/3/efm/public/) was established to provide solutions for the socalled last-mile issue. Currently, a wide variety of protocols provide services to the last mile. They include ISDN, DSL, cable modems, satellite, and broadband wireless solutions, which offer speeds under 10 Mbps. However, existing Intranets use technologies such as Fast and Giga-Ethernet with speed..
The following are examples of NET addresses. AFI 49 means "make up your own address structure." Because we only need to differentiate areas, notice that the IDI has been left out. The first example shows a NET address that uses the host MAC address as the system ID: 49.0005.AA00.0301.16CD.00. When interpreting an address, a Cisco router knows that the first byte is AFI, last byte is SEL, and the preceding six bytes are system ID. Anything between AFI and system ID is in..
The Database Description Packet
The database description (DBD) packet, which is OSPF packet type 2, is sent after routers have listed each other in their hello packets, and after two-way communication has been established. This is the initialization of adjacency. DBD packets describe the contents of link-state databases; describing the entire database requires that multiple packets be sent. During the database-exchange process, one router is elected as master and the other as slave. The master..
Mitigating the Detrimental Effects of the IS-IS Restart
This section describes two different approaches to reduce the negative effects resulting from the original IS-IS restart behavior. The first approach, referred to as the IETF IS-IS restart mechanism, extends the IS-IS protocol and requires that both the restarting router and its neighbors (also known as helper nodes) be restart-capable.[4] As a result, for an adjacency when both neighbors are not IETF IS-IS restart-capable, the IS-IS restart behavior on that adjacency reverts..
Converting Broadcasts to Multicasts
Cisco has a special feature called an IP Multicast Helper, which you can use to convert broadcast packets to multicast packets. Then you can use PIM to send these packets throughout the network. At the last-hop routers you can then convert the multicast packets back to broadcast. This is useful for older broadcast-based applications that do not support multicast transmission. Router1 is the first-hop router, or the one closest to the broadcast source, which is on the interfa..
