> -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Mark Smith > Sent: Saturday, March 13, 2010 6:00 PM > To: Brian E Carpenter > Cc: [email protected] > Subject: Re: [Softwires] SOFTWIRE working group last call on 6rd > > On Sun, 14 Mar 2010 14:19:22 +1300 > Brian E Carpenter <[email protected]> wrote: > > > On 2010-03-14 13:46, Mark Smith wrote: > > ... > > > These are the sorts of scenarios which have made me wonder whether > > > there should be some sort of mechanism to express different off-link > > > and on-link MTUs or on-site and off-site MTUs (distinguished by an > > > on-site aggregate prefix). > > > > I hope they're discussing that over in MIF. A different set of settings > > (not just MTU) per prefix seems entirely rational; a nice large MTU > > for a ULA prefix might make sense. > > > > I've thought you could go a bit further, allowing nodes to have > different MTUs on the local link.
Iljitsch van Beijnum talked about this not long ago: http://tools.ietf.org/id/draft-van-beijnum-multi-mtu-02.txt I talked about it years and years ago: http://tools.ietf.org/id/draft-templin-ndiscmtu-00.txt Fred [email protected] > The current RA announced MTU is made the offlink unicast/multicast MTU, > onlink multicast MTU and default MTU, if the following options aren't > understood. E.g. for the 6RD scenario, this would be 1280 bytes. > > Another RA option is created to announce the maximum MTU of the link, > being the largest that the link supports e.g. the maximum frame > size the link layer can forward. If all switches were configured to > support 9K byte frames, this value would be 9K. This would default to > the normal or common link layer MTU values e.g. 1500 bytes for ethernet. > > A ND NA option is created for a node to announce it's local MRU. A > sending node that understands these RA/ND NA options would then be able > to send unicast packets up to the smallest value of it's local > MTU, the maximum link MTU and the neighbor's MRU. E.g. if the local > interface only supports 8K MTU/MRU, then in that node's NAs it would > announce that 8K MRU, and other nodes that supported 9K MTUs would only > send 8K frames to it. > > > Regards, > Mark. > _______________________________________________ > Softwires mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/softwires _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
