nanog mailing list archives
Re: MTU to CDN's
From: William Herrin <bill () herrin us>
Date: Thu, 18 Jan 2018 19:32:43 -0500
On Thu, Jan 18, 2018 at 7:14 PM, Jared Mauch <jared () puck nether net> wrote:
lets say i can send you a 9K packet. If you receive that frame, and realize you need to fragment, then it’s your routers job to slice 9000 into 5 x 1500.
In practice, no, because the packet you sent had the "don't fragment" bit set. That means my router is not allowed to fragment the packet. Instead, I must send the originating host an ICMP destination unreachable packet stating that the largest packet I can send further is 1500 bytes. You might receive my ICMP message. You might not. After all, I am not the host you were looking for. Good luck. Regards, Bill Herrin P.S. This makes Linux servers happy: iptables -t mangle --insert POSTROUTING --proto tcp \ --tcp-flags SYN,RST,FIN SYN --match tcpmss --mss 1241:65535 \ --jump TCPMSS --set-mss 1240 -- William Herrin ................ herrin () dirtside com bill () herrin us Dirtside Systems ......... Web: <http://www.dirtside.com/>
Current thread:
- MTU to CDN's Dovid Bender (Jan 08)
- Re: MTU to CDN's joel jaeggli (Jan 08)
- Re: MTU to CDN's Mikael Abrahamsson (Jan 08)
- Re: MTU to CDN's Vincent Bernat (Jan 09)
- Re: MTU to CDN's Dovid Bender (Jan 18)
- Re: MTU to CDN's George Michaelson (Jan 18)
- Re: MTU to CDN's Mark Andrews (Jan 18)
- Re: MTU to CDN's George Michaelson (Jan 18)
- Re: MTU to CDN's Jared Mauch (Jan 18)
- Re: MTU to CDN's William Herrin (Jan 18)
- Re: MTU to CDN's Owen DeLong (Jan 18)
- Re: MTU to CDN's Jared Mauch (Jan 18)
- Re: MTU to CDN's William Herrin (Jan 18)
- Re: MTU to CDN's Jared Mauch (Jan 19)
- Re: MTU to CDN's Jared Mauch (Jan 19)
- Re: MTU to CDN's William Herrin (Jan 19)
- Re: MTU to CDN's joel jaeggli (Jan 08)
- Re: MTU to CDN's Radu-Adrian Feurdean (Jan 19)
- Re: MTU to CDN's Mark Andrews (Jan 19)
- Re: MTU to CDN's Mikael Abrahamsson (Jan 19)
- Re: MTU to CDN's Vincent Bernat (Jan 18)