OpenWrt/LEDE Project

  • Status Unconfirmed
  • Percent Complete
  • Task Type Bug Report
  • Category Base system
  • Assigned To No-one
  • Operating System All
  • Severity High
  • Priority Very Low
  • Reported Version openwrt-18.06
  • Due in Version Undecided
  • Due Date Undecided
  • Private
Attached to Project: OpenWrt/LEDE Project
Opened by Alec Robertson - 18.01.2019

FS#2062 - MTU is not set to 1508/1500 when using PPPoE

TP-LINK Archer C7, OpenWrt 18.06.1 r7258-5eb055306f / LuCI openwrt-18.06 branch (git-18.228.31946-f64b152).

Use PPPoE for WAN. Set MTU to 1508.

Observe ifconfig result. MTU is set at 1492, it should be 1500.


config interface ‘eth0’

option ifname 'eth0'
option mtu '1508'

to /etc/config/network, ensure PPPoE MTU (as above) is set to 1508 and restart the network/reboot the router.

Observe ifconfig result. MTU is set at 1500 as expected.

Enrico commented on 05.02.2019 19:06

That's perfectly normal, openwrt automatically account for 8 byte of PPPoE overhead, thus 1500-8=1492.

If your ISP supports mini jumbo frames you could set MTU manually changing the MTU value on the pppoe interface.


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