Re: Internet Exchanges supporting jumbo frames?
What's driving the desire for larger packets? A single bit error will drop a whole packet. Larger packets will cause more loss. Cables will need to be shorter or bitrates lower to compensate. Byte overhead of packet headers? Are we seeing degradation of packets per second in forwarding due to the increase in IPv6? Are we seeing IPv6 packets with hop-by hop extension headers (which forward on the slow path)? Increasing the packet size will reduce the number of TCP packets as well as the number of TCP ack packets. TCP ACK packets are significantly larger in IPv6 than IPv4. TCP slow start is faster with large MTU. Is this an issue? Are IPv6 packets with extension headers causing performance degradation in firewalls? Thanks, Jakob.
Thus spake Jakob Heitz (jheitz) (jheitz@cisco.com) on Fri, Mar 18, 2016 at 09:29:44PM +0000:
What's driving the desire for larger packets?
In our little corner of the internet, it is to increase the performance of a low number of high-bdp flows which are typically dataset transfers. All of our non-commercial peers support 9k. Dale
Then it's mainly TCP slowstart that you're trying to improve? Thanks, Jakob.
-----Original Message----- From: Dale W. Carder [mailto:dwcarder@wisc.edu] Sent: Friday, March 18, 2016 3:03 PM To: Jakob Heitz (jheitz) <jheitz@cisco.com> Cc: nanog@nanog.org Subject: Re: Internet Exchanges supporting jumbo frames?
Thus spake Jakob Heitz (jheitz) (jheitz@cisco.com) on Fri, Mar 18, 2016 at 09:29:44PM +0000:
What's driving the desire for larger packets?
In our little corner of the internet, it is to increase the performance of a low number of high-bdp flows which are typically dataset transfers. All of our non-commercial peers support 9k.
Dale
I would hazard a guess that reducing the packet header overhead *and* the Ethernet interframe gap time by a factor of 6 could make enough of an improvement to be quite noticeable when dealing with huge dataset transfers. Tim McKee -----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Jakob Heitz (jheitz) Sent: Friday, March 18, 2016 18:21 To: Dale W. Carder Cc: nanog@nanog.org Subject: RE: Internet Exchanges supporting jumbo frames? Then it's mainly TCP slowstart that you're trying to improve? Thanks, Jakob.
-----Original Message----- From: Dale W. Carder [mailto:dwcarder@wisc.edu] Sent: Friday, March 18, 2016 3:03 PM To: Jakob Heitz (jheitz) <jheitz@cisco.com> Cc: nanog@nanog.org Subject: Re: Internet Exchanges supporting jumbo frames?
Thus spake Jakob Heitz (jheitz) (jheitz@cisco.com) on Fri, Mar 18, 2016 at 09:29:44PM +0000:
What's driving the desire for larger packets?
In our little corner of the internet, it is to increase the performance of a low number of high-bdp flows which are typically dataset transfers. All of our non-commercial peers support 9k.
Dale
----- No virus found in this message. Checked by AVG - www.avg.com Version: 2015.0.6189 / Virus Database: 4542/11829 - Release Date: 03/17/16
You would hardly notice it. Helium is 4 times as heavy as hydrogen, but only marginally less buoyant. Header overhead: Ethernet=38 IPv4=20 TCP=20 Total=78 Protocol efficiency: 1500: 1500/1578 = 95% 9000: 9000/9078 = 99% That's 4% better for a TCP packet, not 600%. Thanks, Jakob.
On Mar 18, 2016, at 6:45 PM, Tim McKee <tim@baseworx.net> wrote:
I would hazard a guess that reducing the packet header overhead *and* the Ethernet interframe gap time by a factor of 6 could make enough of an improvement to be quite noticeable when dealing with huge dataset transfers.
Tim McKee
-----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Jakob Heitz (jheitz) Sent: Friday, March 18, 2016 18:21 To: Dale W. Carder Cc: nanog@nanog.org Subject: RE: Internet Exchanges supporting jumbo frames?
Then it's mainly TCP slowstart that you're trying to improve?
Thanks, Jakob.
-----Original Message----- From: Dale W. Carder [mailto:dwcarder@wisc.edu] Sent: Friday, March 18, 2016 3:03 PM To: Jakob Heitz (jheitz) <jheitz@cisco.com> Cc: nanog@nanog.org Subject: Re: Internet Exchanges supporting jumbo frames?
Thus spake Jakob Heitz (jheitz) (jheitz@cisco.com) on Fri, Mar 18, 2016 at 09:29:44PM +0000:
What's driving the desire for larger packets?
In our little corner of the internet, it is to increase the performance of a low number of high-bdp flows which are typically dataset transfers. All of our non-commercial peers support 9k.
Dale
----- No virus found in this message. Checked by AVG - www.avg.com Version: 2015.0.6189 / Virus Database: 4542/11829 - Release Date: 03/17/16
The factor of 6 was just in reduction of overhead. Granted in the greater scheme of things the overall 4% is relatively insignificant, but there have been many times when doing multiple 10-100+GB transfers that I would have welcomed a 4% reduction of time spent twiddling thumbs! -----Original Message----- From: Jakob Heitz (jheitz) [mailto:jheitz@cisco.com] Sent: Saturday, March 19, 2016 00:34 To: Tim McKee Cc: Dale W. Carder; nanog@nanog.org Subject: Re: Internet Exchanges supporting jumbo frames? You would hardly notice it. Helium is 4 times as heavy as hydrogen, but only marginally less buoyant. Header overhead: Ethernet=38 IPv4=20 TCP=20 Total=78 Protocol efficiency: 1500: 1500/1578 = 95% 9000: 9000/9078 = 99% That's 4% better for a TCP packet, not 600%. Thanks, Jakob.
On Mar 18, 2016, at 6:45 PM, Tim McKee <tim@baseworx.net> wrote:
I would hazard a guess that reducing the packet header overhead *and* the Ethernet interframe gap time by a factor of 6 could make enough of an improvement to be quite noticeable when dealing with huge dataset transfers.
Tim McKee
-----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Jakob Heitz (jheitz) Sent: Friday, March 18, 2016 18:21 To: Dale W. Carder Cc: nanog@nanog.org Subject: RE: Internet Exchanges supporting jumbo frames?
Then it's mainly TCP slowstart that you're trying to improve?
Thanks, Jakob.
-----Original Message----- From: Dale W. Carder [mailto:dwcarder@wisc.edu] Sent: Friday, March 18, 2016 3:03 PM To: Jakob Heitz (jheitz) <jheitz@cisco.com> Cc: nanog@nanog.org Subject: Re: Internet Exchanges supporting jumbo frames?
Thus spake Jakob Heitz (jheitz) (jheitz@cisco.com) on Fri, Mar 18, 2016 at 09:29:44PM +0000:
What's driving the desire for larger packets?
In our little corner of the internet, it is to increase the performance of a low number of high-bdp flows which are typically dataset transfers. All of our non-commercial peers support 9k.
Dale
----- No virus found in this message. Checked by AVG - www.avg.com Version: 2015.0.6189 / Virus Database: 4542/11829 - Release Date: 03/17/16
----- No virus found in this message. Checked by AVG - www.avg.com Version: 2015.0.6189 / Virus Database: 4542/11841 - Release Date: 03/19/16
-----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Tim McKee
The factor of 6 was just in reduction of overhead. Granted in the greater scheme of things the overall 4% is relatively insignificant, but there have been many times when doing >multiple 10-100+GB transfers that I would have welcomed a 4% reduction of time spent twiddling thumbs!
The 4% increase in available bandwidth is only part of the equation though. I would think that having to encap/decap 1/6 the number of packets(frames) from host to host and all routers/switches along the way would be beneficial, especially since some of these could be processing these in software. Certainly if there are FW or IPS involved. I'm not sure about the host side of things, but I'm guessing there would be efficiency increases there as well. Chuck
On Fri, 18 Mar 2016 21:29:44 -0000, "Jakob Heitz (jheitz)" said:
A single bit error will drop a whole packet. Larger packets will cause more loss. Cables will need to be shorter or bitrates lower to compensate.
If that's an actual concern in your production network, you probably have bigger issues you need to be dealing with....
participants (5)
-
Chuck Church -
Dale W. Carder -
Jakob Heitz (jheitz) -
Tim McKee -
Valdis.Kletnieks＠vt.edu