Internet Exchanges supporting jumbo frames?

Wed Mar 9 16:00:55 UTC 2016

Could you do the same with a 1501 byte packet?

> On Mar 9, 2016, at 10:51 AM, Nick Hilliard <nick at foobar.org> wrote:
> 
> Kurt Kraut wrote:
>> Thank you for replying so quickly. I don't see why the consensus for an
>> MTU must be reached. IPv6 Path MTU Discovery would handle it by itself,
>> wouldn't it? If one participant supports 9k and another 4k, the traffic
>> between them would be at 4k with no manual intervention. If to
>> participants adopts 9k, hooray, it will be 9k thanks do PMTUD.
>> 
>> Am I missing something?
> 
> for starters, if you send a 9001 byte packet to a router which has its
> interface MTU configured to be 9000 bytes, the packet will be
> blackholed, not rejected with a PTB.
> 
> Even if it weren't, how many icmp PTB packets per second would a router
> be happy to generate before rate limiters kicked in?  Once someone
> malicious works that out, they can send that number of crafted packets
> per second through the IXP, thereby creating a denial of service situation.
> 
> There are many other problems, such as pmtud not working properly in the
> general case.
> 
> Nick
> 