Hello Costa
Take a look at the Cisco Feature Navigator to find out what IOS versions support the L2TPv3 feature:
https://cfnng.cisco.com/browse/routing/features
As for Cisco IOS images, take a look at this NetworkLessons note on the subject.
I hope this has been helpful!
Laz
Hi Lagapides,
Thanks for your reply.
In fact what I need is a link where I can download cisco ios which support L2TPv3.
can you help?
Thanks in advance,
Lazaros Agapides via NetworkLessons.com Community Forum <forum@networklessons.com> escreveu no dia quinta, 31/03/2022 Ă (s) 06:19:
Hello Costa
As stated in the NetworkLessons note on downloading IOS images:
GNS3 emulator software is free, but the related Cisco IOS images you require to use it are not. Cisco owns the copyright on IOS so they canât be shared freely. Youâll have to purchase them, or get them from someone who has legal access to them.
If you have purchased the appropriate Cisco support package, you can go to the following Software Download site and get what you need.
https://software.cisco.com/download/home
I hope this has been helpful!
Laz
Hello Rene ; csn you please tell me how to implement L2tp over ipsecsite to site ? Do you have any example for that ?
Thank you .
Hello Mohammad
Cisco has a detailed document describing how to implement L2TP over IPSec. Take a look at this and if you have more specific questions, please feel free to post them here!
I hope this has been helpful!
Laz
Thanks Lagapides . In the cisco Dokument they describe l2tp/ Ipsec between Server und remote Site . My Question is how to implement Ipsec on the same Topology hier ( Site to site ) ? As I think we can add crypto map and transform set and Ikev1 policy to the L2tp Configuration that you did on Topology , is this right ?
Second Question on the G0/2 interface on Router 1 and Router 2 there is no Ip Adress and H1 , H2 are as Arouter layer 3 with Ip Adress how will be this link between Router 1 and H1 up without Io Adress configured on Router 1s Interface ? Can we configure g0/2 with Ip adress ? Can we connect Layer 2 Switch to g0/2 interface or does this link have to be to Router layer 3 with ip adress ?
Sorry for multiple Questions but Im a little confused hier .
Thank you .
Hello Mohammad
As stated in the documentation shared before:
The primary benefit of configuring L2TP with IPsec/IKEv1 in a remote access scenario is that remote users can access a VPN over a public IP network without a gateway or a dedicated line, which enables remote access from virtually anyplace with POTS. An additional benefit is that no additional client software, such as Cisco VPN client software, is required.
Typically, L2TP with IPSec is used to connect individual clients. The only other scenario that matches more closely to a site to site scenario is the one described in this documentation:
In this case, the tunnel is created between two Cisco routers, however, its purpose is to enable a dial-up client to securely access a remote network.
I donât know if L2TP over IPSec can be used as a site to site VPN solution, I have never seen it implemented this way, nor have I found examples of it, however, it may be possible, with experimentation. A more suitable, simpler, scalable, and all-round better solution is to use one of these:
The list above is not exhaustive, there are more options available, depending on your needs and your topology.
The purpose of L2TP is to create a layer 2 tunnel over a layer 3 infrastructure. In this case, G0/2 of both R1 and R2 are acting as layer 2 interfaces, and that is why they are not assigned IP addresses. You can imagine the combination of R1 and R2 and the L2TP tunnel as one big layer 2 switch.
I hope this has been helpful!
Laz
Thank you Laz very much for good Explaination .
In place of H1 and H2 as PCs can I use routers ? If yes then how ?
Hello Shivam
You can indeed use routers in place of H1 and H2. In fact, in the lesson, H1 and H2 are actually routers! The icons are PCs, but for the sake of the lesson, routers were used. You can see this from the fact that when Rene configures H1 and H2, they are configured using the Cisco command line commands.
I hope this has been helpful!
Laz
Hello, i currently have a working l2tpv3 set up (using this lesson), and it works with a couple different devices on a layer2 network so i know its configured correctly;however, a 3rd different device can make connection but cant download an application from the server on the other end (basically connects via the webpage and then freezes during the download) Ive wiresharked this connection (when its actually connected/not over the l2tpv3) and it routinely sends/recieve packets that are 1460 in size. I am Using an ipsec dmvpn tunnel at the edge routers for the Point to point network with starlink. It seems like this combined with the dmvpn, l2tpv3, as well as kg-250xs encryptors would grossly exeed the mtu due to all the additional overhead and cause fragmenting. To solve this, does setting pmtu set up on the pseudowire and then again at the edge router seem like it would work? Do i need to configure both sides for pmtu? Do i need to do just the pseduwire and not the edge router? In the attached image, replace âMBKâ with starlink and router and âgre tunnelâ with ipsec dmvpn.
Note: hosts parameters are not authorized to be changed.
Hello Cole
I think youâve done a good job in walking through the scenario and concluding that it is an MTU issue. Thanks for being so clear in your description as well.
One more check I would suggest you do is to use a ping sweep with a range of sizes to determine the actual MTU size that is being allowed from end to end. The 1460 size sounds reasonable, but itâs worth doing just to see the maximum that is actually allowed. To find out more about how you can do this (assuming you have a Cisco device on the one end) take a look at this NetworkLessons note. You can do this with Linux devices as well, and even with a Windows PC with the appropriate 3rd party tools. Doing a Google search for the topic brings many results.
Having said that, using PMTUD may be a solution to your particular issue. The pseudowire is applied on R1 and R2, correct? Then yes, you would have to configure PMTUD on those devices. To enable PMTUD, you can use the ip tcp adjust-mss command on the router interfaces. This command adjusts the MSS of TCP packets to account for the additional overhead from the encapsulation protocols. You should set the MSS to the MTU size minus the total encapsulation overhead. You can determine what value to use from the results of your ping sweep.
In order for PMTUD to work however, ICMP must be able to send and receive packets freely. Sometimes such packets are blocked by firewalls or services such as Starlink. Also keep in mind that this command only applies to TCP sessions (which includes your web session). UDP will not be affected by this command.
In this lesson, you can find an example of the ip tcp adjust-mss command. Additional information about resolving such issues using PMTUD can be found here.
Let us know how you get along and if we can be of further help!
I hope this has been helpful!
Laz
Hey sir, thanks for the assist. We made some good progress. 2 different devices responded well to the ip pmtu commands under the pseduowire, dramitically improving performance. However, the 3rd device recived the pings (could see them coming back âfragmentation neededâ on wireshark) and upon receipt the hostâs port quickly shut down until we reset the host. Unfortunately we cant modify either hosts settings. We have tried the mss adjust command on any and all ports on both ends that would accept the command, no change to packet size. 1514 size packets go through, there is just a lot of fragmentation that ia slowing down the data/ dup acks/ re-trans/ timeouts etc⌠Any follow on ideas on how to adjust mss values?
Hello Cole
Iâm glad that you made some progress in resolving the issue! Tell me a little bit more about this third device. What kind of device is it? When you see the hostâs port shut down, what kind of error message is indicated? The other two devices that work successfully, what have you done there to make them work, and why isnât that working on the third device? This information will help us to further help you. Let us know when you can!
Thanks!
Laz
