We would request the ability to set the WAN MTU to a value over 1500. We understand that by definition a frame is 1500 bytes and ‘jumbo’ frames are out of specification. But in order to provide an underlay with an MTU of 1500 we would need to be able to set the overlay MTU to say 1600.
Is this something that can be enabled. Perhaps hidden behind a tool tip like some of the nat features, so you can keep the warning about setting your WAN mtu too high. But would allow users who control the last mile to have the Peplink use that higher MTU that is available.
+1 for this, a lot of UK ISPs support “baby” jumbo frames as PPPoE takes the MTU down to 1492, baby jumbo frames allows PPPoE whilst still keeping the MTU at a full 1500: MTU - AAISP Support Site
This is a very interesting request, and I would really like to understand the MRU size advertised by the PPPoE network.
So far, I have not come across an example of a PPPoE network advertising an MRU of 1500. If you are able to share the packet capture with us, it would be very helpful and would give us a valuable reference for this scenario.
You can use the packet capture tools and capture the MRU advertised by the network as the example below :
Both endpoints will send their own PPP LCP Configure-Request packets, and each request may include an MRU value.
Therefore, the packet capture should show the MRU advertised by both sides of the PPPoE connection. This will help us confirm whether the PPPoE network side is actually advertising an MRU of 1500, and whether the client side is accepting or negotiating a different value.
Please allow me to clarify.
For current Peplink devices, when using a PPPoE WAN connection with the MTU setting configured as Auto , the PPPoE client will typically negotiate and accept an MRU of 1492 . At the physical Ethernet layer, the interface continues to operate with a frame size of 1500 bytes .
Therefore, there is no need to manually configure the physical Ethernet MTU size, as the default 1500-byte Ethernet frame size is sufficient for standard PPPoE operation with an MRU of 1492.
It would be helpful to review a packet capture of the PPPoE negotiation to see whether the ISP is advertising an MRU of 1500 bytes during session establishment, or if any additional configuration is required.
If anyone is able to provide a capture, we’d be glad to take a closer look. This would help us better understand how RFC 4638 is being deployed in the field and assess the requirements for supporting this scenario. In particular, we’d like to understand whether automatic MTU/MRU negotiation is sufficient in most deployments, or if manual MTU configuration is commonly required.
Let’s say if anyone has the ISP support 1500 bytes, please let us know with your RA enabled. This will definitely help us to speed things up. You can PM me or create a ticket so we can follow up with you.
Anyone in the UK with an FTTC or FTTP connection delivered across Openreach’s network should be able to do this, it has heen supported for quite a few years now, I think it is also reasonably common in Europe for this to be implemented by the ISPs.
Typically I have always manually configured this across a number of different ISPs and hardware.
In my current setup at home I am using a Cisco ISR to terminate the PPP for my connection with the underlying Ethernet interface that the VDSL modem connects to configured for 1508 MTU to allow for the 8 byte overhead of the PPP headers, and then the PPP interface is set to 1500.
In the case of my Cisco router I have a specific config line that tells it to ignore any kind of advertised MRU in the LCP frames and use what is manually configured.
This question is about setting the MTU of an Ethernet interface above 1500. This operation is currently prohibited by the Peplink NOS. This is supported on pretty much any modern NOS.
Travis, this question has nothing to do with PPPoE.
This thread is about setting the MTU on an Ethernet interface to 1500. Is that going to be supported or is Peplink refusing to support that configuration.
And why is this information not available on the data sheets. I would say your documentation, but as a vendor you have chosen to not document your product.
For information on which models support Jumbo Frames , please refer to the Peplink Router Comparison Tool . It provides the supported features and specifications for each router model.
