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Chapter 3      Configuring Advanced Networks
Connecting a Remote Network to Two Corporate Networks
Step 45c804(config-if)# encapsulation pppEnable PPP.
Step 46c804(config-if)# dialer rotary-group 1
c804(config-if)# dialer rotary-group 2Create dialer rotary groups 1 and 2, 
specifying a number between 0 and 255 for 
each.
Step 47c804(config-if)# isdn spid1 0 4085551212
c804(config-if)# isdn spid2 0 4085551313North America only. Associate the...

 
Chapter 3      Configuring Advanced Networks
Connecting a Remote Network to Two Corporate Networks
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Configuring the Routers at the Corporate Site
Starting from global configuration mode, follow these steps to configure the 
routers that connect the Cisco 800 series router. 
This procedure assumes that these routers are Cisco routers that support 
Cisco IOS software, such as a Cisco 3600 router.
Command Purpose
Step 1router# configure...

 
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Chapter 3      Configuring Advanced Networks
Configuring the ISDN Line
Configuring the ISDN Line
For the ISDN line, you can use one of the following features:
DDR using snapshot routing (the ISDN line is activated only when needed)
Permanent ISDN line lease
This section provides further information on these features and how to configure 
them.
Step 123600(dhcp-config)# default-router 1.1.2.1For configuring DHCP only. Set the Ethernet 
0 IP...

 
Chapter 3      Configuring Advanced Networks
Configuring the ISDN Line
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Dial-on-Demand Routing Using Snapshot Routing
You can configure the DDR feature on your ISDN line. The ISDN line is then 
activated by traffic demands, including sending updates to other routers. You can 
configure snapshot routing to control the duration and frequency of the routing 
updates.
NoteSome protocols (IP, UDP, and NTP) send updates that can cause an ISDN line...

 
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Chapter 3      Configuring Advanced Networks
Configuring the ISDN Line
Step 8router(config-if)# dialer load-threshold 150 
eitherDefine the load level that must be exceeded 
on first ISDN B channel before the second B 
channel is brought up, and whether the load 
level is defined for inbound or outbound 
traffic, or for either type.
Step 9router(config-if)# dialer-group 2Assign interface to dialer access group.
Step 10router(config-if)#...

 
Chapter 3      Configuring Advanced Networks
Configuring the ISDN Line
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Verifying the DDR Configuration
You can test your DDR configuration by making an ISDN data call through the 
CLI as shown in the following steps. For more information on the commands 
shown, refer to the Cisco IOS documentation set.
Configuring a Leased ISDN Line
This section describes how to configure the router so that it uses the ISDN line as 
a leased-line connection...

 
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Chapter 3      Configuring Advanced Networks
Configuring Dynamic Routing
Configuring Dynamic Routing
The IP routing protocol can use RIP or EIGRP to learn routes dynamically. You 
can configure either one of these options. This section also provide information 
on triggered extensions to RIP.
Configuring Routing Information Protocol
RIP is a commonly used Interior Gateway Protocol (IGP) for use in small 
networks. 
Starting in global...

 
Chapter 3      Configuring Advanced Networks
Configuring UDP Broadcasts
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Figure 3-3 Cisco 800 Series Router Forwarding UDP Broadcasts
The router forwards UDP broadcasts containing PC addresses, so that PCs in 
network A can learn about PCs in network B, and vice versa. However, if your 
network uses a DDR ISDN line, the UDP broadcasts might activate this line too 
often. 
If keeping monthly ISDN costs low is a concern, you can control when...

 
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Chapter 3      Configuring Advanced Networks
Configuring DHCP Relay
NoteBy default, eight other UDP ports, including 137 (NetBIOS name server) and 138 
(NetBIOS datagram service), are enabled. For more information, refer to the 
Cisco IOS documentation.
Configuring DHCP Relay
With DHCP, devices on an IP network (DHCP clients) can request configuration 
information from a DHCP server. DHCP allocates IP addresses from a central 
pool as...

 
Chapter 3      Configuring Advanced Networks
Controlling the DDR ISDN Line Activation
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DHCP relay configures the router to forward UDP broadcasts, including IP 
configuration requests, from DHCP clients. However, if your network uses a 
DDR ISDN line, you might find that this line is activated excessively by the IP 
configuration requests and other UDP broadcasts. If keeping monthly ISDN costs 
low is a concern, you can control the activation...