[95972] in North American Network Operators' Group
Re: Thoughts on increasing MTUs on the internet
daemon@ATHENA.MIT.EDU (Gian Constantine)
Thu Apr 12 13:07:47 2007
In-Reply-To: <20070412160729.GA498@mx.ytti.net>
Cc: NANOG list <nanog@merit.edu>
From: Gian Constantine <constantinegi@corp.earthlink.net>
Date: Thu, 12 Apr 2007 13:03:25 -0400
To: Saku Ytti <saku+nanog@ytti.fi>
Errors-To: owner-nanog@merit.edu
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I did a rough, top-of-the-head, with ~60 bytes header (ETH, IP, TCP)
into 1500 and 4470 (a mistake, on my part, not to use 9216).
I still think the cost outweighs the gain, though there are some
reasonable arguments for the increase.
Gian Anthony Constantine
On Apr 12, 2007, at 12:07 PM, Saku Ytti wrote:
>
> On (2007-04-12 16:28 +0200), Iljitsch van Beijnum wrote:
>>
>> On 12-apr-2007, at 16:04, Gian Constantine wrote:
>>
>>> I agree. The throughput gains are small. You're talking about a
>>> difference between a 4% header overhead versus a 1% header overhead
>>> (for TCP).
>>
>> 6% including ethernet overhead and assuming the very common TCP
>> timestamp option.
>
> Out of curiosity how is this calculated?
> [ytti@ytti.fi ~]% echo "1450/(1+7+6+6+2+1500+4+12)*100"|bc -l
> 94.27828348504551365400
> [ytti@ytti.fi ~]% echo "8950/(1+7+6+6+2+9000+4+12)*100"|bc -l
> 99.02633325957070148200
> [ytti@ytti.fi ~]%
>
> I calculated less than 5% from 1500 to 9000, with ethernet and
> adding TCP timestamp. What did I miss?
>
> Or compared without tcp timestamp and 1500 to 4470.
> [ytti@ytti.fi ~]% echo "1460/(1+7+6+6+2+1500+4+12)*100"|bc -l
> 94.92847854356306892000
> [ytti@ytti.fi ~]% echo "4410/(1+7+6+6+2+4470+4+12)*100"|bc -l
> 97.82608695652173913000
>
> Less than 3%.
>
> However, I don't think it's relevant if it's 1% or 10%, bigger
> benefit would be to give 1500 end-to-end, even with eg. ipsec
> to the office.
>
> --
> ++ytti
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<HTML><BODY style=3D"word-wrap: break-word; -khtml-nbsp-mode: space; =
-khtml-line-break: after-white-space; ">I did a rough, top-of-the-head, =
with ~60 bytes header (ETH, IP, TCP) into 1500 and 4470 (a mistake, on =
my part, not to use 9216).<DIV><BR =
class=3D"khtml-block-placeholder"></DIV><DIV>I still think the cost =
outweighs the gain, though there are some reasonable arguments for the =
increase.<DIV><BR><DIV> <SPAN class=3D"Apple-style-span" =
style=3D"border-collapse: separate; border-spacing: 0px 0px; color: =
rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: =
normal; font-variant: normal; font-weight: normal; letter-spacing: =
normal; line-height: normal; text-align: auto; =
-khtml-text-decorations-in-effect: none; text-indent: 0px; =
-apple-text-size-adjust: auto; text-transform: none; orphans: 2; =
white-space: normal; widows: 2; word-spacing: 0px; "><SPAN =
class=3D"Apple-style-span" style=3D"border-collapse: separate; =
border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; =
font-size: 12px; font-style: normal; font-variant: normal; font-weight: =
normal; letter-spacing: normal; line-height: normal; text-align: auto; =
-khtml-text-decorations-in-effect: none; text-indent: 0px; =
-apple-text-size-adjust: auto; text-transform: none; orphans: 2; =
white-space: normal; widows: 2; word-spacing: 0px; "><DIV>Gian Anthony =
Constantine</DIV><BR class=3D"Apple-interchange-newline"></SPAN></SPAN> =
</DIV><BR><DIV><DIV>On Apr 12, 2007, at 12:07 PM, Saku Ytti =
wrote:</DIV><BR class=3D"Apple-interchange-newline"><BLOCKQUOTE =
type=3D"cite"><DIV style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">On (2007-04-12 16:28 +0200), Iljitsch van Beijnum =
wrote:</DIV> <BLOCKQUOTE type=3D"cite"><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: =
14px; "><BR></DIV><DIV style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; ">On 12-apr-2007, at 16:04, Gian =
Constantine wrote:</DIV><DIV style=3D"margin-top: 0px; margin-right: =
0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; =
"><BR></DIV> <BLOCKQUOTE type=3D"cite"><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I agree. The =
throughput gains are small. You're talking about a <SPAN =
class=3D"Apple-converted-space">=A0</SPAN></DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; =
">difference between a 4% header overhead versus a 1% header overhead =
<SPAN class=3D"Apple-converted-space">=A0</SPAN></DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">(for TCP).</DIV> </BLOCKQUOTE><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">6% =
including ethernet overhead and assuming the very common TCP <SPAN =
class=3D"Apple-converted-space">=A0</SPAN></DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; =
">timestamp option.</DIV> </BLOCKQUOTE><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: =
14px; "><BR></DIV><DIV style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; ">Out of curiosity how is this =
calculated?</DIV><DIV style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; ">[<A =
href=3D"mailto:ytti@ytti.fi">ytti@ytti.fi</A> ~]% echo =
"1450/(1+7+6+6+2+1500+4+12)*100"|bc -l</DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; =
">94.27828348504551365400</DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">[<A =
href=3D"mailto:ytti@ytti.fi">ytti@ytti.fi</A> ~]% echo =
"8950/(1+7+6+6+2+9000+4+12)*100"|bc -l</DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; =
">99.02633325957070148200</DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">[<A =
href=3D"mailto:ytti@ytti.fi">ytti@ytti.fi</A> ~]%<SPAN =
class=3D"Apple-converted-space">=A0</SPAN></DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; =
min-height: 14px; "><BR></DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">I calculated =
less than 5% from 1500 to 9000, with ethernet and</DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">adding TCP timestamp. What did I miss?</DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Or =
compared without tcp timestamp and 1500 to 4470.</DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">[<A href=3D"mailto:ytti@ytti.fi">ytti@ytti.fi</A> =
~]% echo "1460/(1+7+6+6+2+1500+4+12)*100"|bc -l</DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">94.92847854356306892000</DIV><DIV style=3D"margin-top:=
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">[<A =
href=3D"mailto:ytti@ytti.fi">ytti@ytti.fi</A> ~]% echo =
"4410/(1+7+6+6+2+4470+4+12)*100"|bc -l</DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; =
">97.82608695652173913000</DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: =
14px; "><BR></DIV><DIV style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; ">Less than 3%.</DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">However, =
I don't think it's relevant if it's 1% or 10%, bigger</DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">benefit would be to give 1500 end-to-end, even with =
eg. ipsec</DIV><DIV style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; ">to the office.</DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">--<SPAN =
class=3D"Apple-converted-space">=A0</SPAN></DIV><DIV style=3D"margin-top: =
0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN =
class=3D"Apple-converted-space">=A0 </SPAN>++ytti</DIV> =
</BLOCKQUOTE></DIV><BR></DIV></DIV></BODY></HTML>=
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