Re: New Version Notification for draft-bonica-6man-frag-deprecate-00.txt

[Mark Andrews <[e-mail]>]

In message <[e-mail]>, "Fred Baker (fred)" writes:
> I suppose I'm the contrarian, but this draft gives me some heartburn surrounding the robustness principle. Yes, 
> TCP MSS generally limits the use of fragmentation for IPv6. We don't have a counterpart to MSS for UDP, and othe
> rs have noted that OSPF etc may have issues. 
> 
> Thinking hypothetically, it would be unusual for OSPF to not be able to manage packet size via LSA choice, but s
> uppose I am on an interface that has a given MTU, and I have a single LSA that is larger than that MTU, perhaps 
> a Router LSA on a wide fan-out unit. Deprecating the fragmentation capability forces each client of the network 
> layer to create a means for fragmentation/segmentation. That might be some other protocol that essentially dupli
> cates what we're deprecating, or it could be something in which a router has to make enough routing instances of
>  itself to split the Router LSA across them, or something like that.
> 
> Personally, I think I would prefer a statement that says that the first fragment MUST contain the transport head
> er (which Fernando has been pushing), and encourages transports and applications to implement some variation on 
> PMTU rather than depending on fragmentation, but not deprecating the capability.

Or additionallty supply the information the firewall is looking for
in a skipable hop-by-hop option.  For UDP that would be the two
ports.  6 to 8 extra octets per fragment.

> --------------------------------------------------------------------
> IETF IPv6 working group mailing list
> [e-mail]
> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
> --------------------------------------------------------------------
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: [phone]                 INTERNET: [e-mail]