Cisco Router 800 Series Software Configuration Guide
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4-63 Cisco 800 Series Software Configuration Guide 78-5372-06 Chapter 4 Network Scenarios Configuring the DHCP Server In this scenario, the small business or remote user on the Ethernet LAN can connect to the Internet through ADSL. The Ethernet interface carries the data packet through the LAN and offloads it to the RFC 1483 connection on the ATM interface. The number of ATM PVCs is set by default. NAT (represented as the dashed line at the edge of the 827 routers) signifies two addressing domains and the inside source address. The source list defines how the packet travels through the network. The following configuration topics are covered in this section: Configuring the Ethernet Interface Configuring the ATM Interface Configuring NAT Configuration Examples To add additional features to this network, see Chapter 7, “Router Feature Configuration.” After configuring your router, you need to configure the PVC endpoint. For a general configuration example, see the “Cisco 3640 Gateway Configuration Example” section on page 4-89. Configuring the Ethernet Interface Complete the following steps to configure the Ethernet interface, beginning in global configuration mode. Callout Number Description 1Small business or remote user 2Connection to Ethernet 0 address 192.168.1.1/24 3ATM 0 PVC 8/35 4The Internet
Chapter 4 Network Scenarios Configuring the DHCP Server 4-64 Cisco 800 Series Software Configuration Guide 78-5372-06 Configuring the ATM Interface Use this table to configure the ATM interface, beginning in global configuration mode. Configuring NAT Complete the follow steps to configure NAT, beginning in global configuration mode. Command Task Step 1interface ethernet 0Enter configuration mode for the Ethernet interface. Step 2ip address 192.168.1.1 255.255.255.0Set the IP address and subnet mask for the Ethernet interface. Step 3no shutdownEnable the Ethernet interface. Step 4exitExit configuration mode for the Ethernet interface. Command Task Step 1interface ATM 0Enter configuration mode for the ATM interface. Step 2ip address 200.200.100.1 255.255.255.0Set the IP address and subnet mask for the ATM interface. Step 3pvc 8/35Create an ATM PVC for each end node with which the router communicates. Step 4protocol ip 200.200.100.254 broadcastSet the protocol broadcast for the IP address. Step 5encapsulation typeSpecify the encapsulation type for the PVC to be AAL5SNAP or AAL5MUX IP. Step 6no shutdownEnable the ATM interface. Step 7exitExit configuration mode for the ATM interface.
4-65 Cisco 800 Series Software Configuration Guide 78-5372-06 Chapter 4 Network Scenarios Configuring the DHCP Server Configuration Examples In the following configuration examples, you do not have to enter the commands marked “default.” These commands appear automatically in the configuration file that is generated when you use the show running-config command. The following example shows an RFC 1483 LLC/SNAP encapsulation over AT M . ! interface Ethernet0 ip address 192.168.1.1 255.255.255.0 no ip directed-broadcast (default) ip nat inside ! interface ATM0 Command Task Step 1ip nat inside source list 1 pool interface ATM0 overloadEnable dynamic translation of addresses permitted by the access list to one of addresses specified in the ATM interface. Step 2ip route 0.0.0.0.0.0.0.0 atm0Set the IP route to point to the ATM interface as a default gateway. Step 3access-list 1 permit 192.168.1.0.0.0.0.255Define a standard access list permitting addresses that need translation. Step 4interface ethernet 0Enter configuration mode for the Ethernet interface. Step 5ip nat insideEstablish the Ethernet interface as the inside interface. Step 6exitExit configuration mode for the Ethernet interface. Step 7interface atm 0Enter configuration mode for the ATM interface. Step 8ip nat outsideEstablish the ATM interface as the outside interface. Step 9exitExit configuration mode for the ATM interface.
Chapter 4 Network Scenarios Configuring the DHCP Server 4-66 Cisco 800 Series Software Configuration Guide 78-5372-06 ip address 200.200.100.1 255.255.255.0 no ip directed-broadcast (default) ip nat outside no atm ilmi-keepalive (default) pvc 8/35 encapsulation aal5snap protocol ip 200.200.100.254 broadcast ! bundle-enable ! ip nat inside source list 1 interface ATM0 overload ip classless (default) ip route 0.0.0.0 0.0.0.0 200.200.100.254 ! access-list 1 permit 192.168.1.0 0.0.0.255 ! end The following is an example for configuring RFC 1483 VC-MUX. ip subnet-zero ! interface Ethernet0 ip address 192.168.1.1 255.255.255.0 no ip directed-broadcast (default) ip nat inside ! interface ATM0 ip address 200.200.100.1 255.255.255.0 no ip directed-broadcast (default) ip nat outside no atm ilmi-keepalive (default) pvc 8/35 encapsulation aal5mux ip protocol ip 200.200.100.254 broadcast ! bundle-enable ! ip nat inside source list 1 interface ATM0 overload ip classless (default) ip route 0.0.0.0 0.0.0.0 200.200.100.254 ! access-list 1 permit 192.168.1.0 0.0.0.255 ! end
4-67 Cisco 800 Series Software Configuration Guide 78-5372-06 Chapter 4 Network Scenarios Configuring the DHCP Server Integrated Routing and Bridging This network shows a user connecting to the Internet using integrated routing and bridging (IRB) to use NAT across a bridged interface. This scenario might work for you if you want to add functionality to an endpoint router without reconfiguring the central site. For example, you can provide an IP address and NAT in a bridged network without having to reconfigure the central site for routing. Exchanging the bridge for a router enables the addition of features such as voice and quality of service (QoS). IRB provides more secure control of the central site and more efficient use of the WAN link. Figure 4-13 and Ta b l e 4 - 1 5 show an IRB Internet scenario. Figure 4-13 IRB Internet Scenario Callout Number Description 1Small business or remote user 2Connection to Ethernet 0 address 192.168.1.1/24 3ATM 0 PVC 8/35 4The Internet Cisco 827/827-4V 192.168.1.1/24DSLAMCisco 6400 Cisco 6400 74580 41 2 3
Chapter 4 Network Scenarios Configuring the DHCP Server 4-68 Cisco 800 Series Software Configuration Guide 78-5372-06 One side of the network (the WAN, in this scenario) is configured to act as a bridge. The Bridge-Group Virtual Interface (BVI) is configured to act as a routed interface from the WAN bridge-group to the nonbridged LAN interface. From the LAN, the network appears as a router. From the WAN, the network appears as a bridge. The ATM interface uses AAL5SNAP encapsulation. The number of PVCs is set by default. NAT (represented as the dashed line at the edge of the Cisco 827 router) signifies two addressing domains and the inside source address. The source list defines how the packet travels through the network. This section covers the following configuration topics: Configuring the Default Gateway Configuring the Ethernet Interface and IRB Configuring the ATM Interface Configuring the BVI Configuring NAT Configuration Example To add more features to this network, see Chapter 7, “Router Feature Configuration.” After configuring your router, you need to configure the PVC endpoint. For a general configuration example, see the “Cisco 3640 Gateway Configuration Example” section on page 4-89. Configuring the Default Gateway Enter the following command to set the IP route for the default gateway: ip route default-gateway ip address-mask Configuring the Ethernet Interface and IRB Complete the following steps to configure the Ethernet interface and IRB, beginning in global configuration mode.
4-69 Cisco 800 Series Software Configuration Guide 78-5372-06 Chapter 4 Network Scenarios Configuring the DHCP Server Configuring the ATM Interface Follow the steps below to configure the ATM interface, beginning in global configuration mode. Command Task Step 1bridge irbSpecify IRB. Step 2bridge 1 route ipEnable IP routing to and from bridge-group 1. Step 3bridge 1 protocol ieeeSpecify the bridge protocol to define the type of Spanning-Tree Protocol (STP). Step 4interface ethernet 0Enter configuration mode for the Ethernet interface. Step 5ip address 192.168.1.1 255.255.255.0Set the IP address and subnet mask for the Ethernet interface. Step 6no shutdownEnable the Ethernet interface. Step 7exitExit configuration mode for the Ethernet interface. Command Task Step 1interface ATM 0Enter configuration mode for the ATM interface. Step 2pvc 8/35Create an ATM PVC for each end node with which the router communicates. Step 3encapsulation aal5snapSpecify the encapsulation type for the PVC. Step 4bridge-group 1Specify the bridge-group number to which the ATM interface belongs. Step 5no shutdownEnable the ATM interface. Step 6exitExit configuration mode for the ATM interface.
Chapter 4 Network Scenarios Configuring the DHCP Server 4-70 Cisco 800 Series Software Configuration Guide 78-5372-06 Configuring the BVI Follow the steps below to configure the BVI, beginning in global configuration mode. Configuring NAT Follow the steps below to configure NAT, beginning in global configuration mode. Command Task Step 1interface bvi 1Enter configuration mode for the BVI. Step 2ip address 200.200.100.1 255.255.255.0Set the IP address and subnet mask for the BVI. Step 3exitExit configuration mode for Ethernet interface. Command Task Step 1ip nat pool test 200.200.100.1 200.200.100.1 255.255.255.0 Create pool of global IP addresses for NAT. Step 2access-list 101 permit ip 192.168.1 0.0.0.0.255 any logDefine a standard access list permitting addresses that need translation. Step 3ip nat inside source list 101 pool test overloadEnable dynamic translation of addresses permitted by the access list to one of the addresses specified in the pool. Step 4interface ethernet 0Enter configuration mode for the Ethernet interface. Step 5ip nat insideEstablish the Ethernet interface as the inside interface. Step 6no shutdownEnable interface and configuration changes just made to the interface. Step 7exitExit configuration mode for the Ethernet interface.
4-71 Cisco 800 Series Software Configuration Guide 78-5372-06 Chapter 4 Network Scenarios Configuring the DHCP Server Configuration Example In the following configuration example, you do not have to enter the commands marked “default.” These commands appear automatically in the configuration file that is generated when you use the show running-config command. bridge irb ! interface Ethernet0 ip address 192.168.1.1 255.255.255.0 no ip directed-broadcast (default) ip nat inside ! interface ATM0 no ip address no ip directed-broadcast (default) ip nat outside no atm ilmi-keepalive (default) pvc 8/35 encapsulation aal5snap ! bridge-group 1 ! interface BVI1 ip address 200.200.100.1 255.255.255.0 Step 8interface ATM 0Enter configuration mode for the ATM interface. Step 9ip nat outsideEstablish the ATM interface as the outside interface. Step 10no shutdownEnable the interface and configuration changes just made to the interface. Step 11exitExit configuration mode for the ATM interface. Step 12interface bvi 1 Enter configuration mode for the BVI. Step 13ip nat outsideEstablish the BVI as the outside interface. Step 14no shutdownEnable the interface and configuration changes just made to the interface. Step 15endExit configuration mode for the BVI. Command Task
Chapter 4 Network Scenarios Configuring the DHCP Server 4-72 Cisco 800 Series Software Configuration Guide 78-5372-06 no ip directed-broadcast (default) ip nat outside ! ip nat pool test 200.200.100.1 200.200.100.1 netmask 255.255.255.0 ip nat inside source list 101 pool test overload ip classless (default) ! bridge 1 protocol ieee bridge 1 route ip ! access-list 101 permit ip 192.168.1.0 0.0.0.255 any log ! ip route 0.0.0.0 0.0.0.0 200.200.100.254 (default gateway) ! end Concurrent Routing and Bridging This network shows a remote user connecting to the Internet using concurrent routing and bridging (CRB) to route voice traffic and bridge data traffic while keeping the two types of traffic separated. This scenario is useful if you want to simplify your network setup for data transmission and then configure voice. The IP address is configured to recognize the difference between data traffic and voice traffic (voice traffic is configured with QoS parameters and virtual circuits). IRB can do routing and bridging on the same interface; CRB does routing and bridging on separate interfaces. Figure 4-14 and Ta b l e 4 - 1 6 show a CRB Internet scenario with the voice traffic routed and the data traffic bridged. Both the Cisco 827/827-4v gateway and the Cisco 3640 voice gateway are supporting voice traffic from telephones.