Figure 27–2 Peering points are interconnection points between two Internet providers.

1. Figure 27–1 MAE sites may be seen as the hubs where the millions of packets of information traveling around the Internet pass through on their way to the Web site. The MAE site houses lots of equipment that routes all of those packets.

2. Figure 27–2 Peering points are interconnection points between two Internet providers.

3. Figure 27–3 Three carriers peering using Border Gateway Protocol (BGP) routing.

4. Figure 27–4 Four devices connected to two network devices. The routing is performed by cracking the packet and reading the source and destination addresses.

5. Figure 27–5 Top-level domains (TLDs) established to organize the Internet into categories. The darker circles represent older standard TLDs; the lighter circles represent the newly designated domains.

6. Figure 27–6 An Internet address is divided into several sections. The first portion of the address routes the packet to the network by using the domain address. Once the packet enters the domain, the address further routes the packet to a subdomain. Finally, the packet is routed to the correct zone by reading the zone address.

7. Figure 27–7 Domains contain subdomains, which contain zones.

8. Figure 27–8 Medium-size ISPs are often referred to as level-2 carriers. Typically, they connect into NAPs and level-1 ISPs.

9. Figure 27–9 Peering points between two large ISPs. Two connections are established between the two networks for reliability. BGP routing is used to exchange routing tables between the two networks. Peering points are established between the two to reduce the number of hops the packets need to travel and, thus, reduce the time it takes the information to travel the net.

10. Figure 27–10 ISPs often establish connections with ILECs or CLECs using ISDN PRI circuits.

11. Figure 27–11 Spidercom connects with XYZ at six different interconnection points. The purpose of interconnecting is to ensure routes between the two networks even during outages.

12. Figure 27–12 SMS is used to terminate circuits carrying DSL signals. The SMS maps the signals onto larger pipes out to the network. It is a Layer 3 device that routes the packets using a Layer 2 protocol.

13. Figure 27–13 An Ethernet switch switches Ethernet traffic. The Ethernet LAN feeds into the switch where the packets are routed to the correct interface port. Many DSLAMs output Ethernet signals that are fed into an Ethernet switch.

14. Figure 27–14 The two core routers are used to interconnect to the outside world in the same way the gateway router connects host routers to the outside world. The access routers feed into the core routers that are responsible for handling all higher-level routing protocols. The purpose of reducing the number of interconnecting routers in the network is to reduce the complexity of the network.

15. Figure 27–15 ATM switches are used to reroute traffic during failures.

16. Figure 27–16 Cache engines are used to store Web site information closer to the end user.

17. Figure 27–17 VPNs allow remote locations to connect through the Internet without establishing point-to-point dedicated circuits.