Routers create an internetwork. - Computers - Certification

Routers create an internetwork.

Switch

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A router creates an internetwork and provides connections to WAN services.

Switch

The network in Figure 1.3 is a pretty cool network. Each host is connected to its own collision domain, and the router has created two broadcast domains. And don't forget that the router pro- vides connections to WAN services as well! The router uses something called a serial interface for WAN connections, specifically, a V.35 physical interface on a Cisco router. Breaking up a broadcast domain is important because when a host or server sends a network broadcast, every device on the network must read and process that broadcast-unless you've got a router. When the router's interface receives this broadcast, it can respond by basically saying, "Thanks, but no thanks," and discard the broadcast without forwarding it on to other net- works. Even though routers are known for breaking up broadcast domains by default, it's important to remember that they break up collision domains as well. There are two advantages of using routers in your network: They don't forward b roadcasts by default.

They can filter the network based on layer 3 (Network layer) information (e.g., IP address).

Four router functions in your network can be listed as follows: Packet switching

Packet filtering

Internetwork communication

Path selection

Remember that routers are really switches; they're actually what we call layer 3 switches (we'll talk about layers later in this chapter). Unlike layer 2 switches, which forward or filter The best network connected to the router is the LAN switch network on the left. Why? Because each port on that switch breaks up collision domains. But it's not all good-all devices are still in the same broadcast domain. Do you remember why this can be a really bad thing? Because all devices must listen to all broadcasts transmitted, that's why. And if your broadcast domains are too large, the users have less bandwidth and are required to process more broad- casts, and network response time will slow to a level that could cause office riots. Once we have only switches in our network, things change a lot! Figure 1.5 shows the net- work that is typically found today. pass your CCNA EXAM in only 3 days!click here to check it out.

access point vs router