pfSense as router: question about MTU to be set on a 10Gbps interface (WAN interface to 10Gbps ISP link)
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@RobbieTT said in pfSense as router: question about MTU to be set on a 10Gbps interface (WAN interface to 10Gbps ISP link):
WiFi is just RF and RF is fun!
I know. I just borrowed this book from the library. It's the first physical book I've read in years, as they didn't have it in an ebook.
I have also done some work with cell phone sites and short haul microwave and got my amateur radio licence almost 52 years ago.
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@JKnott said in pfSense as router: question about MTU to be set on a 10Gbps interface (WAN interface to 10Gbps ISP link):
I have also done some work with cell phone sites and short haul microwave and got my amateur radio licence almost 52 years ago.
5G seemed to go with simplicity and defined requirements; albeit they had to be steered in that direction in the early days. I don't think you could pay them now to do some of the stuff they originally had in mind. It's all about stability as that = printing money.
My background was more on the exploiting, spoofing, denying, intercepting or generally being on the aggressive side of RF. I did also have to sit on the UK board that allocates and manages the RF spectrum. That was the 'not fun' part of RF.
Regarding your thoughts on testing beyond 1500 MTU on a wifi segment. It's harder than you may think with commodity hardware as most have barriers in place to stop you from doing so. Many wifi interfaces deny the opportunity to fettle the interface at all. Some look like you can tweak them but under the hood nothing changes, either due to the OS or the driver/firmware/hardware itself.
There are exceptions of course - macOS lets you control and pass MTU changes to the wifi interface but in more recent version this became limited to a range of 1280 to 1436 MTU. The point to note here is that it will not allow anywhere near the minimum or maximum MTU unless 'auto' is in place (which caps the interface at 1514 MTU). Ironically the only commodity hardware that used to use a wifi MTU above 1514 was also Apple in the guise of AirPort Time Capsules and Express units.
Meanwhile we are seeing a drift to a new-normal MTU of 1280 (1294), so even the 1500 (1514) MTU will start to look relatively capacious.
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@RobbieTT said in pfSense as router: question about MTU to be set on a 10Gbps interface (WAN interface to 10Gbps ISP link):
Meanwhile we are seeing a drift to a new-normal MTU of 1280 (1294),
Where is that? It's definitely a step in the wrong direction.
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@JKnott said in pfSense as router: question about MTU to be set on a 10Gbps interface (WAN interface to 10Gbps ISP link):
Where is that? It's definitely a step in the wrong direction.
We are partially there already due to Google's interpretation of TLS 1.3, HTTPS/3 and QUIC. YouTube for example:
The joys of GAFAM.
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@RobbieTT said in pfSense as router: question about MTU to be set on a 10Gbps interface (WAN interface to 10Gbps ISP link):
We are partially there already due to Google's interpretation of TLS 1.3, HTTPS/3 and QUIC. YouTube for example:
That's not the same as layer 2 technology. VoIP uses even smaller packets. I don't know enough about QUIC etc. to comment.
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@JKnott
L2 spends a lot of time moving formerly-L3 traffic around.️ -
L2 is always moving L3 around, as it doesn't do anything by itself. L3 is encapsulated in L2. Fire up Wireshark and see what's happening.
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@JKnott
The levels in the OSI model are just abstract constructs, they are not protocols or encapsulation methods. They are somewhat dog-eared in the modern era and are more like marker poles for our thinking or short-hand for describing stuff in loose handfuls.
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OK. Here's a Wireshark capture of me starting a SSH session:
You see that line that begins Ethernet II? That's layer 2
Then, a bit further down is Internet Protocol Version 6. That's layer 3
Below that, is Transmission Control Protocol. That's layer 4.
It's beyond this, starting with SSH Protocol that we differ from OSI, with layers 5-7, incorporated into the application layer.So, we have SSH encapsulated in TCP, encapsulated in IPv6, encapsulated in an Ethernet frame. That is the protocol stack we use these days.
BTW, I first learned about TCP/IP through a local college in spring of 1995. I then had a Novell 3.x CNA course and got certified, followed by CNE 4 I then learned more when I was working at IBM, where I did 3rd level support, with the added bonus of token ring and SNA. I have several books on TCP/IP and Ethernet, which I have read cover to cover. And I've had a lot more experience over the years and frequently use Wireshark or the Packet Capture in pfSense, to examine network traffic.
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We may have strayed from the topic here.
