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This chapter provides an overview of the Cisco 805 router, sample networks in which the router is commonly used, and router configuration options.
The Cisco 805 router is designed for small professional offices and runs a subset of Cisco IOS software. This router includes one 10BaseT Ethernet port and one serial port, which can connect EIA/TIA-232, EIA/TIA-449, EIA/TIA-530, EIA/TIA-530A, X.21, and V.35 data terminal equipment (DTE) or data communications equipment (DCE).
For more details on connecting Ethernet and serial devices, refer to the Cisco 805 Router Hardware Installation Guide.
Figure 1-1 and Figure 1-2 show sample networks in which the Cisco 805 router is commonly used.
In the remote-office-to-corporate-office sample network, the remote office is typically a small professional office that is part of a larger corporation, such as a real estate office. Although a majority of its data might exist at the remote office itself, the remote office might also need to exchange data with its larger corporate office. As a result, the remote office needs a connection to the corporate office.
In the small-office-to-Internet Service Provider (ISP) sample network, the small office is typically a small, independent professional office, such as an architectural firm. This type of office needs to access information from the Internet; therefore, it needs a connection to an ISP.
This guide presents several variations of these two sample networks. See Table 1-1 for a summary of the remote-office-to-corporate-office networks and Table 1-2 for a summary of the small-office-to-ISP networks presented in this guide.
The sample networks are ordered from simple to more complex in terms of concepts and configuration: remote-office-to-corporate-office network number 1 is the simplest, while network number 5 is the most complex.
| No. | WAN Options | WAN Encapsulation | Routed Protocols | Other Features |
|---|---|---|---|---|
1 | Synchronous leased line | High-Level Data Link Control (HDLC) | IP | Dynamic IP routing |
2 | Synchronous leased line | Point-to-Point Protocol (PPP) | IP, IPX | Dynamic IP and IPX routing |
3 | X.25 | X.25 | IP, IPX | Dynamic IP and IPX routing |
4 | Asynchronous dial-up line | PPP | IP, IPX |
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5 | Frame Relay | Frame Relay | IP, IPX |
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| No. | WAN Options | WAN Encapsulation | Routed Protocols | Other Features |
|---|---|---|---|---|
1 | Synchronous leased line | PPP | IP | Static IP route |
2 | Asynchronous dial-up line | PPP | IP |
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3 | Frame Relay | Frame Relay | IP |
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The sample networks are provided as models after which you can pattern your network. They cannot, however, anticipate all of your network needs. You can choose not to use features presented in the sample networks or add or substitute features that better suit your needs.
To determine which sample network best suits your needs, you must decide which WAN options (synchronous leased line, asynchronous dial-up line, Frame Relay, or X.25) to use. If you decide to use a synchronous leased line or an asynchronous dial-up line, you must also decide which WAN encapsulation protocol to use.
The following sections provide information to help you decide which WAN options and encapsulation to use.
The most important factor in determining which sample network you use is the WAN option you choose (synchronous leased line, asynchronous dial-up line, Frame Relay, or X.25). Use the following criteria to help you decide which WAN option to use:
To determine bandwidth requirements, you must consider the amount of data that will pass through your network and its speed. In general, an asynchronous modem (dial-up line) provides the least bandwidth, while a synchronous leased line provides the most bandwidth.
In general, a dial-up line is the cheapest because it is not constantly active. Of the WAN options that offer constantly active lines, Frame Relay is the cheapest, then synchronous leased lines, then X.25 lines.
Not all countries and regions have infrastructures for all WAN technologies. Therefore, your selection of WAN options might be limited by what is available. For example, X.25 might be the only WAN option supported in your country. If you are uncertain about your WAN options, contact the WAN service provider in your area.
If you decide to use a synchronous leased line or an asynchronous dial-up line, you must also decide what type of WAN encapsulation to use. Encapsulation is the wrapping of data in a particular protocol header. The type of router that you are connecting to the Cisco 805 router determines the type of WAN encapsulation. If the router you are connecting is a Cisco router that runs IOS software, use HDLC. If the router you are connecting is a Cisco router that does not run IOS software or is a non-Cisco router, use PPP.
This section discusses the features used in the sample networks. You can choose not to use features presented in the sample networks or add or substitute features that better suit your needs.
In general, the remote-office-to-corporate-office sample networks use the dynamic routing protocols IP RIP and IPX RIP to learn the route to the corporate office network. (Instead of using IP RIP, you can use IP EIGRP. IPX EIGRP is not supported.) The exception is network 4 (asynchronous dial-up line, PPP), which uses static IP and IPX routes, which are user-defined routes to reach the corporate office network.
The small-office-to-ISP networks use IP as the only routed protocol. Instead of using a dynamic routing protocol such as RIP to learn the route to the ISP, these networks use a static IP route to reach the ISP. In this situation, a dynamic routing protocol would advertise the small office network routes to the Internet, which is undesirable.
For cost-effectiveness, this sample network assumes that the small office wants to buy as few registered IP addresses as possible from the Network Information Center (NIC) or the ISP. Instead, it will use private, nonregistered IP addresses everywhere except on the serial interface, which needs a registered IP address to access the ISP.
With PPP/IPCP, the Cisco 805 router automatically negotiates a globally unique (registered or public) IP address for the serial interface from the ISP router. With NAT, the Cisco 805 router translates the nonregistered IP addresses used by the small office network hosts into the globally unique IP address used by the serial interface when they access the Internet or vice versa.
For more information, see "Configuring Easy IP (Phase 1)" in "Advanced Features."
Remote-office-to-corporate-office networks 4 and 5 (asynchronous dial-up line, PPP and Frame Relay, respectively) use the Easy IP (Phase 2) feature. Easy IP (Phase 2) combines Dynamic Host Configuration Protocol (DHCP) server and relay.
As an option, remote-office-to-corporate-office network 4 configures the Cisco 805 router as a DHCP server. The DHCP server assigns IP addresses to DHCP clients on the remote office network, thereby automating IP address administration.
Remote-office-to-corporate-office network 5 assumes that your corporate office network has a workstation or PC configured as a DHCP server and that DHCP clients on the remote office network need to access the DHCP server. If this situation applies to you, you can configure the DHCP relay feature on the Cisco 805 router. With this feature configured, the router can relay IP address requests from the LAN interface, over the serial or dialer interface, and to the DHCP server.
For more information, see "Configuring Easy IP (Phase 2)" in "Advanced Features."
Small-office-to-ISP networks 2 and 3 (asynchronous dial-up line with PPP and Frame Relay, respectively) use the firewall feature to block undesired traffic from the ISP. To configure a firewall in these sample networks, you can use either the Cisco 805 Fast Step application (recommended for inexperienced network administrators) or the Cisco IOS software command-line interface (CLI) (recommended for more experienced network administrators).
If you want to configure a firewall in a remote-office-to-corporate-office network, you must use the Cisco IOS CLI.
For information on how to use the Cisco 805 Fast Step application, refer to the application online help. For information on how to configure a firewall using the CLI, refer to the Cisco IOS Firewall Feature Set feature module, which appears on Cisco Connection Online (CCO) only. This feature module also provides conceptual information on the firewall feature.
Small-office-to-ISP network 3 (Frame Relay) uses the NAT overload feature. For cost-effectiveness, this sample network assumes that the small office wants to buy as few registered IP addresses as possible from the NIC or the ISP. Instead, it will use private, nonregistered IP addresses everywhere except on the serial interface, which needs a registered IP address to access the ISP.
You must buy one registered IP address for the serial interface from the ISP, then using NAT overload, all hosts in this sample network can use this registered IP address when accessing the Internet.
For more information, refer to the "Configuring NAT Overload" section in "Advanced Features."
You can configure the router software using the following options:
The Cisco 805 Fast Step software ships with the router; it is also available on Cisco Connection Online (CCO).
You can configure some of the sample networks described earlier in this chapter with Cisco 805 Fast Step. For more information, refer to Table 3-1 and Table 4-1.
You can access a free copy of the Cisco ConfigMaker software at this location:
http://www.cisco.com/warp/public/734/configmkr
The Cisco 805 router runs a subset of Cisco IOS software. Cisco recommends using the command-line interface (CLI) to configure your router if one of the following applies:
You can configure all of the sample networks described earlier in this chapter by using the CLI.
If you need a refresher on how to use Cisco IOS software, go to "Cisco IOS Basic Skills." If you are ready to configure your router, go to "Configuring Remote Office to Corporate Office Networks" or "Configuring Small Office to ISP Networks."
Posted: Wed Jun 16 14:33:57 PDT 1999
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