Configuring the WAN Ports
ADSL Configuration
ADSL can be configured using three different types of encapsulation: PPPoA, PPPoE, and IPoA. Continue configuration with the ADSL type of your choice.
PPPoE
The following commands configure a sample PPPoE topology. The first set configures the LAN interface with directed broadcasts prohibited.
XSR(config)#interface FastEthernet 1
XSR(config-if<F1>)#ip address 192.168.1.1 255.255.255.0
XSR(config-if<F1>)#no ip directed-broadcast
XSR(config-if<F1>)#no shutdown
The commands below configure the ATM interface and sub-interface with a negotiated IP address, PAP username and password, and ban keepalives. They also reset default PVC VPI and VCI values to those requested by the DSL provider. Notice that the Maximum Segment Size (MSS) is set to 1400 bytes for TCP SYN (synchronize) packets. Because a PC connected to a Fast/ GigabitEthernet port may be unable to access Web sites if its MSS setting is too high, subtracting for the PPPoE, IP, TCP, and GRE headers (6, 20, 20, and 24 bytes, respectively) and the PPP Protocol ID should avoid that problem.
XSR(config)#interface ATM 0 XSR(config-if<ATM0/0>)#no shutdown XSR(config-if<ATM0/0>)#interface ATM 0.1 XSR(config-if<ATM0/0.1>)#no shutdown XSR(config-if<ATM0/0.1>)#encapsulation mux pppoe XSR(config-if<ATM0/0.1>)#ip address negotiated XSR(config-if<ATM0/0.1>)#ip mtu 1492 XSR(config-if<ATM0/0.1>)#ip tcp adjust-mss 1400
XSR(config-if<ATM0/0.1>)#ppp pap sent-username user@net password letmein XSR(config-if<ATM0/0.1>)#no ppp keepalive XSR(config-if<ATM0/0.1>)#pvc 0/100
The following optional commands configure two default routes:
XSR(config)#ip route 0.0.0.0 0.0.0.0 30.0.0.10
XSR(config)#ip route 30.0.0.10 255.255.255.255 ATM 0.1
The following optional commands configure NAT:
XSR(config)#access-list 99 permit 192.168.1.0 0.0.0.255
XSR(config)#interface FastEthernet 1
XSR(config-if<F1>)#ip nat source list 99 assigned overload
PPPoA
Enter the following commands to configure PPPoA. The first set configures the LAN interface with directed broadcasts prohibited.
XSR(config)#interface FastEthernet 1
XSR(config-if<F1>)#ip address 192.168.1.1 255.255.255.0
XSR(config-if<F1>)#no ip directed-broadcast
XSR(config-if<F1>)#no shutdown
