Hello all, I am a bit confused regarding the MTU value of the physical ethernet interfaces when there are vlan child interfaces configured, in regard to avoid unneeded fragmentation:
"ifconfig" shows an MTU of 1500 for both the parent and the vlan interface. Should I increase by hand the mtu of the physical parent interface to accommodate the extra bytes for the vlan tags or this is taken care from the operating system someway when you define a physical interface as parent to a vlan one? Also as an extension to the previous question: When using IPSEC tunnels under openbsd, is there a need to increase the physical interface's MTU to accommodate ipsec overhead? And if yes, what would be that "magic" value from your experience? enc0 reports an MTU of 1536 which sounds logical, but that wouldnt prevent fragmentation if the interface that the ipsec traffic originates/terminates is at 1500. Ofc regarding the above, the rest of networking equipment between the ipsec endpoints (switches, routers, etc) has been configured to handle correctly the bigger mtu values. Thanks in advance on any insight Regards, George
