Hello Dear People,
When I do a ping test from my PC, I’d know how to set the MTU, which is max package size +32. When I do the same test from my hAP ac the value looks different, naturally.
Do I have to set the MTU for LAN connectors different from my chosen WAN port?
LAN network should be standard 1500 on all ethernet interfaces and software-defined bridges including the wireless bridge unless you know what you’re doing and require jumbo frames.
WAN MTU depends on your ISP, if it’s PPPoE you need to set ethernet MTU to 1520 on the port which is running the PPPoE client, this will allow any potential RFC4638 from the ISP, and even if it does not, it will advertise your MRU on the PPPoE link as 1500 to the ISP, which you can easily check in the PPPoE client status page. MikroTik auto-detects WAN MTU on PPPoE anyway.
I have two ISPs, both PPPoE. One is 1460 MTU, the other is 1500 MTU (RFC4638). Works well, never had fragmentation problems since my WAN is set correctly and LAN is standard 1500.
My ISP gives me nothing but a pretty useless cable modem router. This thing can’t even be switched into bridge mode. On top of that, I don’t know much about what they are doing. It’s consumer grade internet.
Honestly, I’m not very good at those things. Not a network guy, just a Cloud Architect. But the hAP ac was there and I was able to set it up. Pinging from the Mikrotik, I would calculate an MTU of 1488.
That said, would I calculate the WAN MTU with the ping values from the clients or the Mikrotik?
Remove all WAN config from the modem, it should automatically turn into bridge mode. Then simply replicate the WAN config on the MikroTik.
It’s not reliable to calculate MTU values if the MikroTik is not handling WAN. Just set it to 1500, problem solved.
Yeah, well. There is no access to the modems WAN side for me. It’s a cable Gateway. As I don’t want those “specialists” to have access to all of my network, I am using the Mikrotik.
Should be +28 (20 bytes IP Header + 8 bytes ICMP Header)
Of course you are correct. That’s what I did but made a mistake in the post.