Joe, > -----Original Message----- > From: Joe Touch [mailto:[email protected]] > Sent: Tuesday, May 16, 2017 4:17 PM > To: Templin, Fred L <[email protected]> > Cc: [email protected] > Subject: Re: [Int-area] I-D Action: draft-ietf-intarea-tunnels-05.txt > > Fred, > > Regarding the following point: > > > On 3/28/2017 9:36 AM, Templin, Fred L wrote: > > 19) Section 4.3.3, third paragraph, I thought it was said earlier > > that all ingress/egress pairs must support the same MTU. I > > thought we agreed earlier on that that multi-MTU subnets > > don't work. So, I think it should say that all ingress pairs > > MUST support a uniform MTU. > The cited section allows for ingress/egress pairs that don't support the > same MTU, but then says that the MTU used for that set is the minimum of > those MTUs. > > There's no way (short of configuration management) to ensure that > ingress/egress pairs MUST support the same MTU, but no real value to > requiring that - AFAICT, we just use the min across that set (which is > what that section says to do).
What I am trying to get at is the need for an ingress to determine the minimum before it sends a packet that may be too big for one of the multipoint link egresses. On IPv6 links, this could be through receipt of an MTU option in a Router Advertisement message. Other ways are possible (e.g., static configuration) but there needs to be some way for all ingresses to determine the minimum. Thanks - Fred > So yes, we do not *use* different MTUs per-destination, but we don't > need to require it AFAICT. > > Joe _______________________________________________ Int-area mailing list [email protected] https://www.ietf.org/mailman/listinfo/int-area
