Re: [Bier] draft-ietf-bier-oam-requirements-00: PMTUD requirement in BIER OAM Requirements

["[e-mail]" <[e-mail]>]

On Sun, Nov 08, 2015 at 01:59:00AM +0000, Antoni Przygienda wrote:
> > Aka: Technically i'd be interested to evaluate if we could do proactive PMTUD
> > for end-to-end BIER. Aka: via signaling of link-MTU in the IGP that BIER uses -
> > and calculating the path MTU to each BFER from it.
> > Or just calculating network-wide min-MTU from link-MTU in the IGP.
> 
>  [Tony saiz:]  feasible but it relies on the riuoting underlay propagating this information.  Not sure that's a good assumption, especially since the end-hosts are not necessarily expected to run the IGP (it's not clearly spelled out in the architecture  today but I can easily imagine a BIER default-GW for an end-host and then this information does not exist in the originator of the PMTU.)

Right. At this point in time it seems to me as if BFRs must paerticipate in eg:
an IGP, so can't be "stupid hosts". I would like "hosts" to partake in BIER, but
i would like to avoid loosing information in the process.

[rant] Just look at IoT where every host partakes in the routing protocol. Much simpler
model than what we have done OSI and IETF for the last decades: come up with separate
"ES-IS" signaling, and for every piece of info that a router has, we have to come up
with an often equivalent but different way to let the hosts know about them. We already see
IMHO in homenet how this will not nearly work as well as if the host would just partake
in routing.  And MIF PVD ... pass back routing information to some DHCP server 
to then end it back to the host... *yikes* [/rant]

Cheers
    Toerless