Allied Telesis L2TP Tunnel User's Manual
Contents
1. Our example uses two office sites that are connected via a WAN connection over the Internet using an L2TP tunnel for security The setup shown below shows the Central office and Remote office routers connected in this case back to back via their Ethernet interfaces this would likely be the remote WAN connection across the Internet with perhaps static IP assignment from the ISPs VLAN 2 IP 222 222 2 1 OSPF used on local VLAN networks VLAN IP 222 222 1 1 Central office router LJ EJE JE JIE Jes A POWER 192 168 1 1 EthO IP 10 10 10 1 RIP propogates VLAN OSPF PPPO routes Over L2TP tunnel WAN L2TP tunnel to remote router 192 168 2 1 EthO IP 10 10 10 2 HIED POWER ETHO eee uy Remote office router OSPF used on VLAN I IP 200 200 1 1 local VLAN networks VLAN 2 IP 200 200 2 I rip I2tp eps_ J Page 2 AlliedWare OS How To Note Dynamic Routing over L2TP An example scenario for RIP over L2TP Network Operation There is a single static route configured to bring up the L2TP tunnel and a secure point to point connection PPPO is established over the L2TP tunnel between the Central and Remote office routers This allows secure communication between the offices across the Internet Each local office site is using OSPF as their routing protocol as it offers some advanced routing features and is scalable and flexible The loca2. 10 1 add ip rip int ppp0 send rip2 receive rip2 set ip riptimer update 15 invalid 90 holddown 60 flush 150 set ospf routerid 200 200 1 1 rip both add ospf area backbone stubarea off summary send add ospf range 200 200 1 0 area backbone mask 255 255 255 0 add ospf range 200 200 2 0 area backbone mask 255 255 255 0 add ospf interface vlanl area backbone add ospf interface vlan2 area backbone enable ospf USA Headquarters 19800 North Creek Parkway Suite 100 Bothell WA 98011 USA T 1 800 424 4284 F 1 425 481 3895 European Headquarters Via Motta 24 6830 Chiasso Switzerland T 41 91 69769 00 F 41 91 69769 11 Asia Pacific Headquarters Tai Seng Link Singapore 534182 T 65 6383 3832 F 65 6383 3830 www alliedtelesis com 2008 Allied Telesis Inc All rights reserved Information in this document is subject to change without notice Allied Telesis is a trademark or registered trademark of Allied Telesis Inc in the United States and other countries All company names logos and product designs that are trademarks or registered trademarks are the property of their respective owners C613 16037 00 REV C Connecting The World AV Allied Telesis
3. MVM Allied Telesis AlliedWare OS How To Configure Dynamic Routing Over An L2TP Tunnel Introduction This How To Note shows an example of using a dynamic routing protocol over an L2TP tunnel Running dynamic routing protocols over a secure Internet connection can be a complex issue with the possibility of intermittent connections causing routing problems OSPF or BGP are more connection oriented than RIP and therefore are more susceptible to problems caused by intermittent loss of connection between neighbours A neighbour that may bounce up and down can cause havoc to the correct propagation of OSPF routing information for a network The following example scenario is for setting up RIP over an L2TP tunnel RIP is simpler and has less overhead and control so it provides a more robust setup as a dynamic routing protocol over an L2TP tunnel Which products does it apply to This Note applies to the following Allied Telesis routers running software version 2 6 1 or later e AR400 series e AR700 series www alliedtelesis com C613 16037 00 REV C An example scenario for RIP over L2TP Related How To Notes You may also find the following How To Notes useful e How To Configure Remote L2TP Tunnels How To Configure Allied Telesis and Cisco Routers To Interoperate Over L2TP How To Notes are available from www alliedtelesis com resources literature howto aspx An example scenario for RIP over L2TP
4. able 12tp server both add 12tp call tunnel rem tunnel ip 10 10 10 2 ty virtual prec in create vlan vlan2 vid 2 add vlan 2 port 3 4 create ppp 0 over tnl tunnel set ppp 0 bap off username chap password chap enable ip add ip int ethO ip 10 10 10 1 mask 255 255 255 0 add ip int pppO0 ip 192 168 1 1 add ip int vlanl ip 222 222 1 1 add ip int vlan2 ip 222 222 2 1 add ip rou 10 10 10 0 mask 255 255 255 0 int eth0 next 10 10 10 2 add ip rip int ppp0 send rip2 receive rip2 set ip riptimer update 15 invalid 90 holddown 60 flush 150 set ospf routerid 222 222 1 1 rip both add ospf area backbone stubarea off summary send add ospf range 222 222 1 0 area backbone mask 255 255 255 0 add ospf range 222 222 2 0 area backbone mask 255 255 255 0 add ospf interface vlan1 area backbone add ospf interface vlan2 area backbone enable ospf Page 5 Allied Ware OS How To Note Dynamic Routing over L2TP Remote Office Router set system name Remote_Office enable 12tp enable 12tp server both add 12tp call tunnel rem tunnel ip 10 10 10 1 ty virtual prec out create vlan vlan2 vid 2 add vlan 2 port 3 4 create ppp 0 over tnl tunnel set ppp 0 bap off username chap password chap enable ip add ip int pppO0 ip 192 168 1 2 add ip int ethO ip 10 10 10 2 mask 255 255 255 0 add ip int vlanl ip 200 200 1 1 add ip int vlan2 ip 200 200 2 1 add ip rou 10 10 10 0 mask 255 255 255 0 int ethO next 10 10
5. ip 2 100 200 200 2 0 255 255 255 0 192 168 1 2 pppO 627 remote 0 rip 2 100 42225222 1 5 0 255 255 255 0 0 0 0 0 vlan1 644 direct 0 interface 1 0 222 222 1 0 255 255 255 0 0 0 0 0 vlani 641 remote 0 ospf Intra 1 10 222 222 2 0 255 255 255 0 0 0 0 0 vlan2 644 direct 0 interface 1 0 222 222 2 0 255 255 255 0 0 0 0 0 vlan2 636 remote 0 ospf Intra 1 10 Page 3 Allied Ware OS How To Note Dynamic Routing over L2TP An example scenario for RIP over L2TP Routing Considerations A routing issue to consider in this set up is the fact that RIP is relatively slow to react to route changes as it only updates by default every 30 seconds To improve the responsiveness of RIP you can alter the default timers for updating flushing and so on You do need to keep in mind that if you lose some packets quite possible across a lossy Internet connection some of your routes may flap too much So the RIP timers need to be adjusted to provide an optimal compromise between responsiveness and robustness In this particular example the various RIP timers are set at half default value set ip riptimer update 15 invalid 90 holddown 60 flush 150 Consideration would need to be given to each specific set up to get an optimal balance when adjusting these timers Page 4 AlliedWare OS How To Note Dynamic Routing over L2TP Configurations Configurations Central Office Router set system name Central_Office enable 12tp en
6. l VLAN networks in our example at each office site use OSPF RIP is used across the secure Internet connection between offices to provide a more robust network as discussed previously So RIP is used on the point to point interface PPPO over the L2TP tunnel OSPF is configured to import and export routing information with RIP This allows RIP to propagate the dynamically learnt OSPF local VLAN network information to the other office router Routing Information The routing table in each router shows locally learnt routes and the routes learnt from the remote router via RIP across the L2TP tunnel The example output below is from the show ip route command on the Central office router You can see that the local VLAN networks 222 222 1 0 and 222 222 2 0 have been learnt via OSPF The Remote office OSPF VLAN networks 200 200 1 0 and 200 200 2 0 have been learnt via RIP These were exported from OSPF on the Remote router and propagated by RIP over the secure point to point connection PPPO using the L2TP tunnel IP Routes Destination Mask NextHop Interface Age Type Policy Protocol Metrics Preference 10 10 10 0 255 255 255 0 0 0 0 0 etho 644 direct 0 interface 1 0 10 10 10 0 255 255 255 0 10 10 10 2 etho 644 direct 0 static 1 60 10 10 10 0 255 255 255 0 192 168 1 2 pppO 627 remote 0 rip 2 100 192 168 1 0 255 255 255 0 0 0 0 0 pppO 644 direct 0 interface 1 0 200 200 1 0 255 255 255 0 192 168 1 2 pppO 627 remote 0 r
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