Overview

This chapter presents the following information:

Overview of network examples described in this manual and the features used in each example.
Cisco 800 series router software configuration tools.

Table 1-1 presents basic networks designed for inexperienced network administrators who want to configure a simple network using the Cisco 800 series router. It also describes the features used in the basic networks. Table 1-2 shows advanced networks for experienced administrators who want to configure a more complex network. Table 1-3 describes additional network features that you can configure in your advanced network. You can use Table 1-3 in conjunction with Table 1-2.

Note Some protocols (IP, User Datagram Protocol [UDP], IPX, and Network Time Protocol [NTP]) send updates that can cause an ISDN line to be activated too often. For information on preventing this situation, refer to the "Controlling the DDR ISDN Line Activation" section in Chapter 4, "Configuring Advanced Networks."

Table 1-1: Basic Network Examples

Network Example Networking Profile Supporting Features

Private IP network to Internet

Do not want to buy registered IP addresses from an Internet service provider (ISP)

Want to conserve network address space

Want to protect router from device attempting to access it through an ISDN line

Want to keep monthly costs associated with ISDN line low

Want to set up a simple routing topology

Do not want to manually assign and maintain IP information

Network Address Translation (NAT) overload uses one address for multiple hosts.

Internet Protocol Control Protocol (IPCP) configures a router to automatically negotiate its IP address from the router it is attempting to connect to.

Challenge Handshake Authentication Protocol (CHAP) or Password Authentication Protocol (PAP) uses a password to authenticate the device accessing your router. For information on CHAP and PAP, see the "Selecting PPP Authentication Protocol" section in Appendix A, "Concepts."

Dial-on-demand routing (DDR) configures your router to activate your ISDN line only when needed.

Static route defines one path to a destination.

Dynamic Host Configuration Protocol (DHCP) server sets up your router to assign IP addresses, subnet masks, and default gateways to workstations configured as DHCP clients.

Public IP network to Internet

Want to conserve network address space

Want to protect router from device attempting to access it through an ISDN line

Want to keep monthly costs associated with ISDN line low

Want to set up a simple routing topology

Do not want to manually assign and maintain IP information

IPCP configures your router to automatically negotiate its IP address from the router it is attempting to connect to.

CHAP or PAP uses a password to authenticate the device accessing your router. For information on CHAP and PAP, see the "Selecting PPP Authentication Protocol" section in Appendix A, "Concepts."

DDR configures your router to activate your ISDN line only when needed.

Static route defines one path to a destination.

DHCP server sets up your router to assign IP addresses, subnet masks, and default gateways to workstations configured as DHCP clients.

Remote office network to corporate office network using IP and IPX

Want to conserve network address space

Want to protect router from device attempting to access it through ISDN line

Want to keep monthly costs associated with ISDN line low

Want to set up a simple routing topology

Do not want to manually assign and maintain IP information

Want to route IP and IPX

IPCP configures your router to automatically negotiate its IP address from the router it is attempting to connect to.

CHAP or PAP uses a password to authenticate the device accessing your router. For information on CHAP and PAP, see the "Selecting PPP Authentication Protocol" section in Appendix A, "Concepts."

DDR configures your router to activate your ISDN line only when needed.

Static route defines one path to a destination.

DHCP server sets up your router to assign IP addresses, subnet masks, and default gateways to workstations configured as DHCP clients.

IP and IPX routing configures routing using IP and IPX protocols.

Network Example	Networking Profile	Supporting Features
Private IP network to Internet	Do not want to buy registered IP addresses from an Internet service provider (ISP) Want to conserve network address space Want to protect router from device attempting to access it through an ISDN line Want to keep monthly costs associated with ISDN line low Want to set up a simple routing topology Do not want to manually assign and maintain IP information	Network Address Translation (NAT) overload uses one address for multiple hosts. Internet Protocol Control Protocol (IPCP) configures a router to automatically negotiate its IP address from the router it is attempting to connect to. Challenge Handshake Authentication Protocol (CHAP) or Password Authentication Protocol (PAP) uses a password to authenticate the device accessing your router. For information on CHAP and PAP, see the "Selecting PPP Authentication Protocol" section in Appendix A, "Concepts." Dial-on-demand routing (DDR) configures your router to activate your ISDN line only when needed. Static route defines one path to a destination. Dynamic Host Configuration Protocol (DHCP) server sets up your router to assign IP addresses, subnet masks, and default gateways to workstations configured as DHCP clients.
Public IP network to Internet	Want to conserve network address space Want to protect router from device attempting to access it through an ISDN line Want to keep monthly costs associated with ISDN line low Want to set up a simple routing topology Do not want to manually assign and maintain IP information	IPCP configures your router to automatically negotiate its IP address from the router it is attempting to connect to. CHAP or PAP uses a password to authenticate the device accessing your router. For information on CHAP and PAP, see the "Selecting PPP Authentication Protocol" section in Appendix A, "Concepts." DDR configures your router to activate your ISDN line only when needed. Static route defines one path to a destination. DHCP server sets up your router to assign IP addresses, subnet masks, and default gateways to workstations configured as DHCP clients.
Remote office network to corporate office network using IP and IPX	Want to conserve network address space Want to protect router from device attempting to access it through ISDN line Want to keep monthly costs associated with ISDN line low Want to set up a simple routing topology Do not want to manually assign and maintain IP information Want to route IP and IPX	IPCP configures your router to automatically negotiate its IP address from the router it is attempting to connect to. CHAP or PAP uses a password to authenticate the device accessing your router. For information on CHAP and PAP, see the "Selecting PPP Authentication Protocol" section in Appendix A, "Concepts." DDR configures your router to activate your ISDN line only when needed. Static route defines one path to a destination. DHCP server sets up your router to assign IP addresses, subnet masks, and default gateways to workstations configured as DHCP clients. IP and IPX routing configures routing using IP and IPX protocols.

Table 1-2: Advanced Network Examples

Network Example Networking Profile Supporting Feature

Private IP network to Internet and corporate network using IP and IPX routing

Want to conserve network address space

Do not want to buy registered IP addresses from an ISP

Want to protect router from device attempting to access it through an ISDN line

Do not want to manually assign and maintain IP information

Want to route IP or IPX

IPCP configures a router to automatically negotiate its IP address from the router it is attempting to connect to.

NAT overload uses one address for multiple hosts.

CHAP or PAP uses a password to authenticate the device accessing your router. For information on CHAP and PAP, see the "Selecting PPP Authentication Protocol" section in Appendix A, "Concepts."

DHCP server sets up your router to assign IP addresses, subnet masks, and default gateways to workstations configured as DHCP clients.

IP and IPX routing configures routing using IP and IPX protocols.

Also see Table 1-3.

Remote office network to two corporate office networks using IP and IPX routing

Want to conserve network address space

Want to protect router from device attempting to access it through ISDN line

Do not want to manually assign and maintain IP information

Want to route IP or IPX

IPCP configures your router to automatically negotiate its IP address from the router it is attempting to connect to.

CHAP or PAP uses a password to authenticate the device accessing your router. For information on CHAP and PAP, see the "Selecting PPP Authentication Protocol" section in Appendix A, "Concepts."

DHCP server sets up your router to assign IP addresses, subnet masks, and default gateways to workstations configured as DHCP clients.

IP and IPX routing configures routing using IP and IPX protocols.

Also see Table 1-3.

Network Example	Networking Profile	Supporting Feature
Private IP network to Internet and corporate network using IP and IPX routing	Want to conserve network address space Do not want to buy registered IP addresses from an ISP Want to protect router from device attempting to access it through an ISDN line Do not want to manually assign and maintain IP information Want to route IP or IPX	IPCP configures a router to automatically negotiate its IP address from the router it is attempting to connect to. NAT overload uses one address for multiple hosts. CHAP or PAP uses a password to authenticate the device accessing your router. For information on CHAP and PAP, see the "Selecting PPP Authentication Protocol" section in Appendix A, "Concepts." DHCP server sets up your router to assign IP addresses, subnet masks, and default gateways to workstations configured as DHCP clients. IP and IPX routing configures routing using IP and IPX protocols. Also see Table 1-3.
Remote office network to two corporate office networks using IP and IPX routing	Want to conserve network address space Want to protect router from device attempting to access it through ISDN line Do not want to manually assign and maintain IP information Want to route IP or IPX	IPCP configures your router to automatically negotiate its IP address from the router it is attempting to connect to. CHAP or PAP uses a password to authenticate the device accessing your router. For information on CHAP and PAP, see the "Selecting PPP Authentication Protocol" section in Appendix A, "Concepts." DHCP server sets up your router to assign IP addresses, subnet masks, and default gateways to workstations configured as DHCP clients. IP and IPX routing configures routing using IP and IPX protocols. Also see Table 1-3.

Table 1-3: Advanced Network Features

Feature Feature Profile Description

ISDN line features:

DDR using snapshot routing

Leased ISDN line

DDR using snapshot routing:

Want to keep monthly costs associated with ISDN line low

Want to control duration and frequency of routing updates and therefore how often ISDN line is activated

Leased ISDN line:

Anticipate high level of network traffic and routing updates over ISDN line

Do not care about monthly costs associated with ISDN line

DDR with snapshot routing DDR activates ISDN line only when network traffic demands (includes routing updates). Snapshot routing controls duration and frequency of routing updates.

Also see the triggered extensions to RIP and DDR ISDN line activation control features in this table.

Leased ISDN line is permanently active.

Dynamic routing:

Routing Information Protocol (RIP)

Triggered extensions to RIP

Enhanced Interior Gateway Routing Protocol (EIGRP)

RIP:

Small network with 15 or fewer hops to reach destination

Want an easy-to-configure routing protocol

Triggered extensions to RIP:
Want to suppress RIP updates so that ISDN line is not activated excessively

EIGRP:

Larger network with 16 or more hops to reach destination

Want to use a metric based on a least-cost path to a destination that is guaranteed to not be part of a routing loop

RIP is an easy-to-configure routing protocol based on RFC 1058 that is used in small networks.

Triggered extensions to RIP cause RIP to send updates only when the routing data base is updated.

EIGRP is a Cisco proprietary routing protocol used in small to medium networks. You can use this routing protocol for multiprotocol routing environments, minimizing size of routing tables and amounts of routing information.

For more information on RIP and EIGRP, see the "Selecting IP Routing Protocols" section in Appendix A, "Concepts." For more information on triggered extensions to RIP, refer to the Cisco IOS documentation.

UDP broadcasts feature

Have Windows NT network

Have network that contains a small number of PCs

A common problem in a
Windows NT environment is that PCs in network A do not know about PCs in network B. With this feature enabled, router forwards UDP broadcasts containing PC addresses.

Possible problem caused by this feature is excessive activation of DDR ISDN line. For a solution to this problem, see the DDR ISDN line activation control feature in this table.

DHCP relay

Want to eliminate task of manually assigning IP addresses to network devices

Want IP addresses assigned by corporate office

Want to prevent IP address assignment accidents

Configures your router to relay IP configuration information from DHCP client on remote network to specified DHCP server on corporate network.

Possible problem caused by this feature is excessive activation of DDR ISDN line. For a solution to this problem, see the DDR ISDN line activation control feature in this table.

DDR ISDN line activation control. Control the following traffic types:

UDP broadcasts associated with Windows NT and DHCP relay environments

IP broadcasts

IPX

NTP

Want to minimize activation of DDR ISDN line and keep monthly ISDN costs low

Configures an extended access list to permit or deny specified traffic.

Network access restrictions

Want users to access the Internet

Do not want outsiders to access the network

Determine access that you want to permit and deny, and configure an extended access list.

Dial-in authentication and authorization

Want to determine who can access your network and what services are authorized for each user

Purchase and install CiscoSecure ACS for Windows NT.

X.25 on ISDN

Anticipate heavy X.25 traffic

Uses 9.6 kbps of bandwidth on the ISDN BRI D channel to transport X.25 packets. (The D channel normally carries control and signalling information only.)

Always on/dynamic (AO/DI) ISDN

Anticipate heavy X.25 traffic

Configures your router to transport X.25 packets using the ISDN BRI D channel. When you need additional bandwidth to transport Point-to-Point Protocol (PPP) packets, you can activate the B channels.

Connecting telephone

Want to use ISDN line for transmission of voice as well as data calls

You can use your ISDN line to transmit voice calls.

Feature	Feature Profile	Description
ISDN line features: DDR using snapshot routing Leased ISDN line	DDR using snapshot routing: Want to keep monthly costs associated with ISDN line low Want to control duration and frequency of routing updates and therefore how often ISDN line is activated Leased ISDN line: Anticipate high level of network traffic and routing updates over ISDN line Do not care about monthly costs associated with ISDN line	DDR with snapshot routing DDR activates ISDN line only when network traffic demands (includes routing updates). Snapshot routing controls duration and frequency of routing updates. Also see the triggered extensions to RIP and DDR ISDN line activation control features in this table. Leased ISDN line is permanently active.
Dynamic routing: Routing Information Protocol (RIP) Triggered extensions to RIP Enhanced Interior Gateway Routing Protocol (EIGRP)	RIP: Small network with 15 or fewer hops to reach destination Want an easy-to-configure routing protocol Triggered extensions to RIP: Want to suppress RIP updates so that ISDN line is not activated excessively EIGRP: Larger network with 16 or more hops to reach destination Want to use a metric based on a least-cost path to a destination that is guaranteed to not be part of a routing loop	RIP is an easy-to-configure routing protocol based on RFC 1058 that is used in small networks. Triggered extensions to RIP cause RIP to send updates only when the routing data base is updated. EIGRP is a Cisco proprietary routing protocol used in small to medium networks. You can use this routing protocol for multiprotocol routing environments, minimizing size of routing tables and amounts of routing information. For more information on RIP and EIGRP, see the "Selecting IP Routing Protocols" section in Appendix A, "Concepts." For more information on triggered extensions to RIP, refer to the Cisco IOS documentation.
UDP broadcasts feature	Have Windows NT network Have network that contains a small number of PCs	A common problem in a Windows NT environment is that PCs in network A do not know about PCs in network B. With this feature enabled, router forwards UDP broadcasts containing PC addresses. Possible problem caused by this feature is excessive activation of DDR ISDN line. For a solution to this problem, see the DDR ISDN line activation control feature in this table.
DHCP relay	Want to eliminate task of manually assigning IP addresses to network devices Want IP addresses assigned by corporate office Want to prevent IP address assignment accidents	Configures your router to relay IP configuration information from DHCP client on remote network to specified DHCP server on corporate network. Possible problem caused by this feature is excessive activation of DDR ISDN line. For a solution to this problem, see the DDR ISDN line activation control feature in this table.
DDR ISDN line activation control. Control the following traffic types: UDP broadcasts associated with Windows NT and DHCP relay environments IP broadcasts IPX NTP	Want to minimize activation of DDR ISDN line and keep monthly ISDN costs low	Configures an extended access list to permit or deny specified traffic.
Network access restrictions	Want users to access the Internet Do not want outsiders to access the network	Determine access that you want to permit and deny, and configure an extended access list.
Dial-in authentication and authorization	Want to determine who can access your network and what services are authorized for each user	Purchase and install CiscoSecure ACS for Windows NT.
X.25 on ISDN	Anticipate heavy X.25 traffic	Uses 9.6 kbps of bandwidth on the ISDN BRI D channel to transport X.25 packets. (The D channel normally carries control and signalling information only.)
Always on/dynamic (AO/DI) ISDN	Anticipate heavy X.25 traffic	Configures your router to transport X.25 packets using the ISDN BRI D channel. When you need additional bandwidth to transport Point-to-Point Protocol (PPP) packets, you can activate the B channels.
Connecting telephone	Want to use ISDN line for transmission of voice as well as data calls	You can use your ISDN line to transmit voice calls.