what's the correct mtu/rmu in wireless interface?

RouterOS General
1

Hello!
My wireless clients connecting via PPPoe.The client have very big ping packets!Minimumm ping packet 15ms! :open_mouth:
I have wireless “b” network!The 1472 mtu not work!
What’s the correct mtu?
Thank you for advance! :wink:

2

Generally, we have found 1492 to be a good maximum, for the PPPoE tunnels. For the wireless interface (or ethernet), you should leave it at 1500, at a minimum. Cleints will usually negotiate lower on their own, if they don’t like it.

I’m not really clear on what you see as the problem, though.

In what way does a 1472 MTU “not work”?

Is the problem that oversized packets need to be fragmented, and the extra latency caused by fragmentation is unacceptable?

Why does the client have “very big ping packets”?, and what is “very big”?

–Eric

3

Hello!
Why does the client have “very big ping packets”?, and what is “very big”?
The client connect pppoe server!I can ping the server in pppoe interface,minimumm ping packet 15ms.I can tested the network static ip, and the ping packet 1-2-3ms.

In what way does a 1472 MTU “not work”?
I find the post.:
If it’s 802.11b, 1480 will NOT work for MTU/MRU. Should be 1472, regardless of what TCP Optimizer says.

1500 for ethernet - 20 for 802.11b overhead - 8 for ppp overhead = 1472

4

There is no 20 byte overhead for 802.11b in the TCP/IP datagram.

For a detailed explanation of wireless overhead take a look at this article:

http://180.uninett.no/wlan/throughput.html

Regards

Andrew