Enterasys Networks Security Router X-PeditionTM - Manual (Page 321)

Configuration Examples
XSR User’s Guide 13-9
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 1/0
XSR(config-if)#no shutdown
XSR(config-if)#interface ATM 1/0.1
XSR(config-if)#no shutdown
XSR(config-if)#encapsulation mux pppoe
XSR(config-if)#ip address negotiated
XSR(config-if)#ip mtu 1492
XSR(config-if)#ip tcp adjust-mss 1400
XSR(config-if)#ppp pap sent-username user@net password letmein
XSR(config-if)#no ppp keepalive
XSR(config-if)#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 1/0.1
The following optional commands configure NAT:
XSR(config)#access-list 99 permit 192.168.1.0 0.0.0.255
XSR(config)#interface FastEthernet1
XSR(config-if)#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 FastEthernet1
XSR(config-if)#ip address 192.168.1.1 255.255.255.0
XSR(config-if)#no ip directed-broadcast
XSR(config-if)#no shutdown
The commands below configure the ATM interface and sub-interface with a negotiated IP
address, CHAP username and password, and bans keepalives.
XSR(config)#interface ATM 1/0
XSR(config-if)#no shutdown
XSR(config-if)#interface ATM 1/0.1
XSR(config-if)#no shutdown
XSR(config-if)#encapsulation snap pppoa
XSR(config-if)#ip address negotiated
XSR(config-if)#ip mtu 1492
XSR(config-if)#ip tcp adjust-mss 1400
XSR(config-if)#ppp chap hostname red password sox
XSR(config-if)#no ppp keepalive
Note: If you have configured a VPN tunnel and wish to avoid intermittent Web browser
problems, add the crypto ipsec df-bit clear command to your configuration.