Table Of Contents
Modems in a Mobile Environment
Roaming with External Wireless Modems
Modems in a Mobile Environment
This chapter describes roaming with external wireless modems.
Roaming with External Wireless Modems
General Packed Radio Service/Code Division Multiplex Access (GPRS/CDMA) modems provide the mobile access router with a Layer 2 roaming interface. The Mobile IP stack allows layer 3 roaming IP connectivity for the mobile access router. External modems are connected to a serial interface of the mobile access router. The serial interface should be running in asynchronous mode. Figure 13-1 shows a sample scenario in which the serial port of the mobile access router is connected to a CDMA modem.
Figure 13-1 Modem to Mobile Access Router Connection
The mobile access router supports the following modems:
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Airlink Raven
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Configuration Example
The example configurations shown in Figure 13-2 and Figure 13-3 demonstrate the router's ability to roam back and forth between 802.11b and Cellular technologies. The browser-based applications and video move dynamically to and from the different technologies. The 1X technology provides approximately 60 Kbps. The Nextel provides approximately 20 Kbps, but the network provides for static IP addresses and private links back to the headquarters. Implementing IPsec VPN in the mobile access router provides a secure connection back to the headquarters through 802.11b technology.
Figure 13-2 IPsec VPN Connection
Figure 13-3 Wireless Internet Connection
Example of a Mobile Access Router with Dialer Interface and GRE Mobile IP Tunneling
chat-script airlink-cdma "" "AT&C1&D2" TIMEOUT 30 OK "ATDT#19788" TIMEOUT 30 CONNECT!interface Loopback0ip address 15.4.1.2 255.255.255.0!interface FastEthernet0/0ip address 10.20.1.1 255.255.255.0!interface Serial1/0physical-layer asyncno ip addressencapsulation pppdialer in-banddialer pool-member 1dialer-group 1!interface Dialer0ip address negotiatedip nat outsideip mobile router-service roamip mobile router-service collocatedencapsulation pppdialer pool 1dialer idle-timeout 0dialer string 1dialer persistentdialer-group 1!ip mobile secure home-agent 64.161.107.162 spi 100 key hex 12345678123456781234567812345678 algorithm md5 mode prefix-suffixip mobile routeraddress 15.4.1.2 255.255.255.0home-agent 64.161.107.162reverse-tunneltunnel mode gre!line 1exec-timeout 0 5flush-at-activationscript dialer airlink-cdmamodem InOutno exectransport input allstopbits 1speed 115200flowcontrol hardwareline aux 0exec-timeout 0 0speed 115200line vty 0 4exec-timeout 0 0password ciscologging synchronousloginExample of a Mobile Access Router Without Dialer Interface
hostname 3200!chat-script airlink-cdma "" "AT&C1&D0" TIMEOUT 30 OK "ATDT#19788" TIMEOUT 30 CONNECT!interface Loopback0ip address 15.4.1.2 255.255.255.0!interface Serial1/0physical-layer asyncmtu 1450bandwidth 115200ip address negotiatedip mobile router-service roamip mobile router-service collocatedencapsulation pppkeepalive 900dialer in-banddialer idle-timeout 0dialer string airlink-cdmadialer-group 1async default routingasync mode interactiveno peer default ip addressno fair-queueno ppp lcp fast-start!router mobile!ip mobile secure home-agent 64.161.107.162 spi 100 key hex 12345678123456781234567812345678 algorithm md5 mode prefix-suffixip mobile routeraddress 15.4.1.2 255.255.255.0home-agent 64.161.107.162!dialer-list 1 protocol ip permit!line con 0exec-timeout 0 0logging synchronousstopbits 1!line 1exec-timeout 0 0flush-at-activationscript dialer airlink-cdmaloginmodem InOutno exectransport input allautoselect during-loginautoselect pppstopbits 1speed 115200flowcontrol hardware!line aux 0exec-timeout 0 0speed 115200line vty 0 4exec-timeout 0 0password ciscologging synchronousloginExample of a Mobile Access Router with Multiple Wireless Connections
ip dhcp excluded-address 10.10.10.1!ip dhcp pool testpoolimport allnetwork 10.10.10.0 255.255.255.0default-router 10.10.10.1 255.255.255.0dns-server 204.117.214.10!ip cefchat-script airlink-cdma2 "" "ATDT#19788" TIMEOUT 60 "CONNECT"chat-script tmobile "" "AT" TIMEOUT 5 OK "ATE0V1" TIMEOUT 5 OK "ATS0=0" TIMEOUT 5 OK "AT+CGATT=1" TIMEOUT 5 OK "AT+CGACT=1,1" TIMEOUT 5 OK "ATD*99***1#" TIMEOUT 10 CONNECTchat-script anydata "" "AT&C1&D0" TIMEOUT 30 OK "ATDT#777" TIMEOUT 30 CONNECT!interface FastEthernet0/0ip address 10.10.10.1 255.255.255.0!interface Serial2/0physical-layer asyncno ip addressencapsulation pppdialer in-banddialer pool-member 1dialer-group 1no keepalive!interface Serial2/1physical-layer asyncno ip addressencapsulation pppshutdowndialer in-banddialer pool-member 2no keepalive!interface Dialer0ip address negotiatedip mobile router-service roam priority 130ip mobile router-service collocated registration retry 3ip mobile router-service collocatedencapsulation pppdialer pool 1dialer idle-timeout 0dialer string 1dialer persistentdialer-group 1ppp authentication pap callin optional!interface Dialer1ip address negotiatedip mobile router-service roamip mobile router-service collocated registration retry 3ip mobile router-service collocatedencapsulation pppdialer pool 2dialer idle-timeout 0dialer string 2dialer persistentdialer-group 2ppp chap hostname 4082029572ppp chap password 0 vzw!ip mobile secure home-agent 64.161.107.162 spi 100 key ascii hello algorithm md5 mode prefix-suffixip mobile routeraddress 20.20.20.1 255.255.255.0collocated single-tunnelhome-agent 64.161.107.162mobile-network FastEthernet0/0reverse-tunneltunnel mode gre!line 5exec-timeout 0 5flush-at-activationscript dialer airlink-cdma2modem InOutno exectransport input allstopbits 1speed 115200flowcontrol hardwareline 6exec-timeout 0 5flush-at-activationscript dialer anydatamodem InOutno exectransport input allstopbits 1speed 115200flowcontrol hardwareExample of a Home Agent Configuration
hostname HomeAgent!ip subnet-zero!no ip domain-lookup!ip audit notify logip audit po max-events 100!fax interface-type fax-mailmta receive maximum-recipients 0!interface Loopback0ip address 10.10.100.1 255.255.255.0!interface FastEthernet0/0ip address 64.161.107.162 255.255.255.248duplex autospeed auto!ip classlessip route 0.0.0.0 0.0.0.0 64.161.107.161ip http serverip pim bidir-enableip mobile home-agentip mobile virtual-network 15.4.0.0 255.255.0.0ip mobile host 15.4.1.2 virtual-network 15.4.0.0 255.255.0.0ip mobile secure host 15.4.1.2 spi 100 key hex 12345678123456781234567812345678!line con 0exec-timeout 0 0logging synchronousline aux 0line vty 0 4exec-timeout 0 0password ciscologging synchronouslogin!endInitialization Strings
Recommended initialization strings for some common modems are provided in Table 13-1, but be aware that Cisco does not warrant that they are suitable or current. When in doubt, refer to the modem vendor's documentation or technical support.
