I tested this on devstack and indeed when I was changing MTU for private network, values on qr- ports in router's namespace were updated.
When I was changing MTU on public network, qg- port in snat- namespace was also updated properly.
But in both cases MTU on rfp- and fpr- ports were not changed.
IMO it should be changed accordingly to MTU change for public network but I would like confirmation for that from some L3 experts like Brian or LIU Yulong :)
I tested this on devstack and indeed when I was changing MTU for private network, values on qr- ports in router's namespace were updated.
When I was changing MTU on public network, qg- port in snat- namespace was also updated properly.
But in both cases MTU on rfp- and fpr- ports were not changed.
IMO it should be changed accordingly to MTU change for public network but I would like confirmation for that from some L3 experts like Brian or LIU Yulong :)