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Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes)

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  Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes) rhkramer@gmail.com - 2017-02-06 23:30 +0100
    Re: Why packets (from my ISP to me) on the WAN VC side of my router  are twice the size of packets on the Ethernet (and a corresponding twice as  many bytes) Dan Purgert <dan@djph.net> - 2017-02-07 00:40 +0100
      Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes) rhkramer@gmail.com - 2017-02-07 01:20 +0100
        Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes) Lisi Reisz <lisi.reisz@gmail.com> - 2017-02-07 01:30 +0100
      Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes) rhkramer@gmail.com - 2017-02-07 01:30 +0100
        Re: Why packets (from my ISP to me) on the WAN VC side of my router  are twice the size of packets on the Ethernet (and a corresponding twice as  many bytes) Dan Purgert <dan@djph.net> - 2017-02-07 11:40 +0100
          Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes) rhkramer@gmail.com - 2017-02-07 14:20 +0100
            Re: Why packets (from my ISP to me) on the WAN VC side of my router  are twice the size of packets on the Ethernet (and a corresponding twice as  many bytes) Dan Purgert <dan@djph.net> - 2017-02-09 13:40 +0100
              Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes) rhkramer@gmail.com - 2017-02-09 14:10 +0100
                Re: Why packets (from my ISP to me) on the WAN VC side of my router  are twice the size of packets on the Ethernet (and a corresponding twice as  many bytes) <tomas@tuxteam.de> - 2017-02-09 14:20 +0100
                Re: Why packets (from my ISP to me) on the WAN VC side of my router  are twice the size of packets on the Ethernet (and a corresponding twice as  many bytes) Dan Purgert <dan@djph.net> - 2017-02-09 17:00 +0100
                Re: Why packets (from my ISP to me) on the WAN VC side of my router  are twice the size of packets on the Ethernet (and a corresponding twice as  many bytes) GiaThnYgeia <GiaThnYgeia@openmailbox.org> - 2017-02-09 17:30 +0100

#177506 — Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes)

I'm the guy who was gobsmacked by the amount of data we (my son and I) are 
sucking down from our ISP (Earthlink via DSL).

I've found something else that I don't understand.  I'm going to keep this 
general at first--if anybody needs specifics, I'll try to provide them.

I've now collected data for something over a week from the Westell DSL modem 
that also serves as a router for the connection between my LAN and Earthlink.

I'veI'm the guy who was gobsmacked by the amount of data we (my son and I) are 
sucking down from our ISP (Earthlink via DSL).

I've found something else that I don't understand.  I'm going to keep this 
general at first--if anybody needs specifics, I'll try to provide them.

I've now collected data for something over a week from the Westell DSL modem 
that also serves as a router for the connection between my LAN and Earthlink.

I've been watching the Ethernet side data, and the WAN VC side.

IIUC, data that I download from Earthlink is labeled "Data Out" on the WAN VC 
side, and is labeled "Data In" on my LAN / Ethernet side.

I would expect these to be fairly close to equal, especially because there is 
almost no traffic between devices on the LAN--believe it or not, on the rare 
occasions that I need to exchange data with another LAN device, I use either 
sneakernet (well, really, pendrive net) or gmail net (I send an email to 
myself (@gmail.com) and open it on the other computer--which means that the 
data goes up and out to Earthlink and eventually back in to the other 
computer.  (I use a little trick to make that work, but it works, and, at 
most, I may send such an email once or twice a month.)

The "anomaly" that I see is that there are twice as many bytes (octets) coming 
in (Data Out) on the WAN VC side as are going out to my LAN (Data In) on the 
Ethernet / LAN side.

Now, the number of packets are about the same, and the difference mainly is 
that the packet size on the VC WAN "Data Out" are about twice the size of the 
packets on the Ethernet / LAN side.

Aside: On data in the other direction (that is, to Earthlink), the number of 
bytes (octets), packets, and size of the packets are all about the same for 
the VC WAN and the Ethernet LAN.

My questions are:

   * Why are there twice as many bytes measured coming in (from Earthlink) 
measured on the WAN VC side of the router as measured on the Ethernet / LAN 
side of the router (or, I guess the analagous question is why are the packets 
twice as big?  (I mean, is the information encoded differently there or 
something?)
   
   * And, can I do something to change that? been watching the Ethernet side 
data, and the WAN VC side.

IIUC, data that I download from Earthlink is labeled "Data Out" on the WAN VC 
side, and is labeled "Data In" on my LAN / Ethernet side.

I would expect these to be fairly close to equal, especially because there is 
almost no traffic between devices on the LAN--believe it or not, on the rare 
occasions that I need to exchange data with another LAN device, I use either 
sneakernet (well, really, pendrive net) or gmail net (I send an email to 
myself (@gmail.com) and open it on the other computer--which means that the 
data goes up and out to Earthlink and eventually back in to the other 
computer.  (I use a little trick to make that work, but it works, and, at 
most, I may send such an email once or twice a month.)

The "anomaly" that I see is that there are twice as many bytes (octets) coming 
in (Data Out) on the WAN VC side as are going out to my LAN (Data In) on the 
Ethernet / LAN side.

Now, the number of packets are about the same, and the difference mainly is 
that the packet size on the VC WAN "Data Out" are about twice the size of the 
packets on the Ethernet / LAN side.

Aside: On data in the other direction (that is, to Earthlink), the number of 
bytes (octets), packets, and size of the packets are all about the same for 
the VC WAN and the Ethernet LAN.

My questions are:

   * Why are there twice as many bytes measured coming in (from Earthlink) 
measured on the WAN VC side of the router as measured on the Ethernet / LAN 
side of the router (or, I guess the analagous question is why are the packets 
twice as big?  (I mean, is the information encoded differently there or 
something?)
   
   * And, can I do something to change that?

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#177510 — Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes)

rhkramer@gmail.com wrote:
>
>    * Why are there twice as many bytes measured coming in (from
>    Earthlink) measured on the WAN VC side of the router as measured on
>    the Ethernet / LAN side of the router (or, I guess the analagous
>    question is why are the packets twice as big?  (I mean, is the
>    information encoded differently there or  something?)
>    
>    * And, can I do something to change that?

Could be MTU differences, and the router needing to do something (e.g.
1500 on the LAN side, and 1452 on the WAN, which is usually typical for
DSL / PPPoE connections).

It's a bit hard to figure out what you're actually seeing happen though,
since your post somehow repeated itself several times, in a pretty big
mess (there wasn't a given start / end of one post, but rather several
copies interleaved).


-- 
|_|O|_| Registered Linux user #585947
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: 05CA 9A50 3F2E 1335 4DC5  4AEE 8E11 DDF3 1279 A281

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#177511

On Monday, February 06, 2017 06:24:40 PM Dan Purgert wrote:
> It's a bit hard to figure out what you're actually seeing happen though,
> since your post somehow repeated itself several times, in a pretty big
> mess (there wasn't a given start / end of one post, but rather several
> copies interleaved).

Oops, sorry about that.  

I'll send a new email and make sure that is corrected.

Explanation (for anyone that cares ;-) My mouse is giving up the ghost, often 
issuing two clicks when I click it instead of just one--I wrote the email in 
another editor and then copied / pasted it to an email using my mouse--it 
apparently clicked twice and inserted the text twice.

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#177513

On Tuesday 07 February 2017 00:13:42 rhkramer@gmail.com wrote:
> On Monday, February 06, 2017 06:24:40 PM Dan Purgert wrote:
> > It's a bit hard to figure out what you're actually seeing happen though,
> > since your post somehow repeated itself several times, in a pretty big
> > mess (there wasn't a given start / end of one post, but rather several
> > copies interleaved).
>
> Oops, sorry about that.
>
> I'll send a new email and make sure that is corrected.
>
> Explanation (for anyone that cares ;-) My mouse is giving up the ghost,
> often issuing two clicks when I click it instead of just one--I wrote the
> email in another editor and then copied / pasted it to an email using my
> mouse--it apparently clicked twice and inserted the text twice.

The copy that reached me was worse than that.  Just twice would have been a 
doddle!!  Several, interleaved.  Perhaps descend from the heady heights of 
FLOSS and use ctrl-C, ctrl-V for now?

Lisi

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#177512

On Monday, February 06, 2017 06:24:40 PM Dan Purgert wrote:
> Could be MTU differences, and the router needing to do something (e.g.
> 1500 on the LAN side, and 1452 on the WAN, which is usually typical for
> DSL / PPPoE connections).

BTW, thanks Dan for your response--I hope the resent email is at least a 
little easier to understand.

Maybe the following should be ignored, at least for now, because it seems it 
would just add confusion to the situation:  I do have a spreadsheet of the 
data I'm collecting (with some other data thrown in--I could trim that out and 
send that to anybody that thought it would be helpful).

<the stuff that should probably be ignored:>

So, I guess the possibility that this suggests to me seems backwards--that is, 
the opposite of what I am seeing.  I mean, if somewhere a 1500 byte packet has 
to be packed into a 1452 byte packet, I suppose something might double the 
size of the 1452 byte packet and just waste the leftover bytes in the two 
packets (i.e., 1452 * 2 -1500 = 1404), but the packets are coming in on the 
WAN side presumably at 1452 bytes and I would think they would fit fine in the 
1500 byte packet on the LAN side.

(And I'm oversimplifying or misleading a little, because I'm not seeing twice 
as many packets but instead packets that are twice as big (on the WAN side).)

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#177521 — Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes)

rhkramer@gmail.com wrote:
> On Monday, February 06, 2017 06:24:40 PM Dan Purgert wrote:
>> Could be MTU differences, and the router needing to do something (e.g.
>> 1500 on the LAN side, and 1452 on the WAN, which is usually typical for
>> DSL / PPPoE connections).
>
> BTW, thanks Dan for your response--I hope the resent email is at least a 
> little easier to understand.

Yeah, will "essentially" start over there, hopefully it won't be too
much a mess :)

>
><the stuff that should probably be ignored:>
>
> So, I guess the possibility that this suggests to me seems
> backwards--that is, the opposite of what I am seeing.  I mean, if
> somewhere a 1500 byte packet has to be packed into a 1452 byte packet,
> I suppose something might double the size of the 1452 byte packet and
> just waste the leftover bytes in the two packets (i.e., 1452 * 2 -1500
> = 1404), but the packets are coming in on the WAN side presumably at
> 1452 bytes and I would think they would fit fine in the 1500 byte
> packet on the LAN side.
>
> (And I'm oversimplifying or misleading a little, because I'm not
> seeing twice as many packets but instead packets that are twice as big
> (on the WAN side).)


-- 
|_|O|_| Registered Linux user #585947
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: 05CA 9A50 3F2E 1335 4DC5  4AEE 8E11 DDF3 1279 A281

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#177526

I noticed today that those statistics pages do tell me the size of the MTUs

On the:       MTU is: 
WAN VC        1540
Ethernet      1500

So, the numbers are a little different, but still relate the same way Dan 
mentioned, that is, the WAN VC MTU is larger than the Ethernet MTU.  (So this 
doesn't add anything to the discussion except to make one point more 
accurate.)


On Tuesday, February 07, 2017 05:27:18 AM Dan Purgert wrote:
> > So, I guess the possibility that this suggests to me seems
> > backwards--that is, the opposite of what I am seeing.  I mean, if
> > somewhere a 1500 byte packet has to be packed into a 1452 byte packet,
> > I suppose something might double the size of the 1452 byte packet and
> > just waste the leftover bytes in the two packets (i.e., 1452 * 2 -1500
> > = 1404), but the packets are coming in on the WAN side presumably at
> > 1452 bytes and I would think they would fit fine in the 1500 byte
> > packet on the LAN side.
> > 
> > (And I'm oversimplifying or misleading a little, because I'm not
> > seeing twice as many packets but instead packets that are twice as big
> > (on the WAN side).)

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#177596 — Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes)

rhkramer@gmail.com wrote:
> I noticed today that those statistics pages do tell me the size of the MTUs
>
> On the:       MTU is: 
> WAN VC        1540
> Ethernet      1500
>

Yuck.  Hate it when people start mucking around with MTUs ... 


-- 
|_|O|_| Registered Linux user #585947
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: 05CA 9A50 3F2E 1335 4DC5  4AEE 8E11 DDF3 1279 A281

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#177598

On Thursday, February 09, 2017 07:21:58 AM Dan Purgert wrote:
> rhkramer@gmail.com wrote:
> > I noticed today that those statistics pages do tell me the size of the
> > MTUs
> > 
> > On the:       MTU is:
> > WAN VC        1540
> > Ethernet      1500
> 
> Yuck.  Hate it when people start mucking around with MTUs ...

If somebody was mucking about with MTUs it tweren't me.  I'm guessing those 
are set in the modem, and Earthlink provided the modem--maybe they changed 
something.  (And maybe they are who I should ask about the twice as many bytes 
issue--but I guess I have to be ready to deal with the support people in 
India--IIRC from last time, I can insist on speaking to a native English 
speaker....)

I'm fighting a headache again, and have to shovel some snow this morning, I'll 
try to reply to your outer post sometime later in the day.

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#177600 — Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes)

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Thu, Feb 09, 2017 at 08:00:15AM -0500, rhkramer@gmail.com wrote:
> On Thursday, February 09, 2017 07:21:58 AM Dan Purgert wrote:
> > rhkramer@gmail.com wrote:
> > > I noticed today that those statistics pages do tell me the size of the
> > > MTUs
> > > 
> > > On the:       MTU is:
> > > WAN VC        1540
> > > Ethernet      1500
> > 
> > Yuck.  Hate it when people start mucking around with MTUs ...
> 
> If somebody was mucking about with MTUs it tweren't me.  I'm guessing those 
> are set in the modem, and Earthlink provided the modem--maybe they changed 
> something.  (And maybe they are who I should ask about the twice as many bytes 
> issue--but I guess I have to be ready to deal with the support people in 
> India--IIRC from last time, I can insist on speaking to a native English 
> speaker....)

This is the result of PPPoE or something similar: your packets are being
wrapped in other packets (e.g. PPP) which go between your provider and
your router), and all that goes in Ethernet (which has a payload of
1500 for "normal" frames). Of course, the wrapper's headers (in my example
above PPP) have to go somewhere, and that are the missing 60 bytes.

Needless to say, *if* it's PPPoE this is mostly superfluous these days
and just historical ballast: but I guess the people at your provider's
knowing this and able to do something about it have long been outsourced.

Yah. I'm becoming a cynic.

Cheers, nevertheless :-)
- -- tomás
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#177606 — Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes)

rhkramer@gmail.com wrote:
> On Thursday, February 09, 2017 07:21:58 AM Dan Purgert wrote:
>> rhkramer@gmail.com wrote:
>> > I noticed today that those statistics pages do tell me the size of the
>> > MTUs
>> > 
>> > On the:       MTU is:
>> > WAN VC        1540
>> > Ethernet      1500
>> 
>> Yuck.  Hate it when people start mucking around with MTUs ...
>
> If somebody was mucking about with MTUs it tweren't me.  I'm guessing
> those are set in the modem [...]

Yes, Earthlink is mucking aound with MTUs.  As (I think) has been
previously mentioned, Ethernet is 1500 bytes.

TYPICALLY one would see that a MTU is *lowered* on a pppoe connection,
rahter than *raised*.  Suppose at the end of the day, if the guys
handling it know what they're doing, it doesn't much matter one way or
the other -- but it can cause loads of "fun" problems, especially when
the guys who know what they're doing end up training their third-world
contractor replacements.

-- 
|_|O|_| Registered Linux user #585947
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: 05CA 9A50 3F2E 1335 4DC5  4AEE 8E11 DDF3 1279 A281

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#177609 — Re: Why packets (from my ISP to me) on the WAN VC side of my router are twice the size of packets on the Ethernet (and a corresponding twice as many bytes)

Old India like new india and oceania are all old British colonies, no
native English speakers there.  Ask the Scots and the Irish to tell you
all about their native languages.

rhkramer@gmail.com:
> I have to be ready to deal with the support people in
> India--IIRC from last time, I can insist on speaking to a native English 
> speaker ....)

Katrin (a 2nd headache)

--
"Let's not talk about Hitler in front of the Germans, it is not polite!"
on top10 funniest lines of Faulty Towers

"And take your damn pipeline back to London" a native Sioux proverb

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