IP MTU on gif and gre interfaces (with and without IPSec encryption)

[Victor Sudakov]

Dear Colleagues,

If the MTU on the external Ethernet interface is 1500, it should be safe
to configure the gif(4) interfaces with mtu=1480 and gre(4)
interfaces with mtu=1476, correct?

I've noticed that a newly created gre0 interface has the expected "mtu 1476"
value, but a newly created gif0 interface has "mtu 1280", why would the
default be so low?

A second question. If the gif and gre tunnels will be wrapped in
IPSec transport mode, does it make sense to set the MTU on the
corresponding gif and gre interfaces to some lower value?


-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
2:5005/49 at fidonet http://vas.tomsk.ru/
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