Is via-ethernet option deleted?

[yutayu]

Does that mean we don't need to bother minus ethernet overhead 14 from ppp overhead?

[chromi]

On 6 Feb, 2020, at 4:34 am, yutayu notifications@github.com wrote:

That means we don't need to bother minus ethernet overhead 14 from ppp overhead?

The overhead is now calculated from the underlying IP packet size, and not from the raw reported packet size which could "sometimes" include Ethernet framing. The latter was the reason for the via-ethernet option, which is therefore no longer needed.

• Jonathan Morton

[yutayu]

@chromi I got meaning.Thanks.:)

[yutayu]

In addition , Does it needs to set mpu behind LAN? My recognization is , When settled bandwidth is for internet , so we don't need to set mpu. When settled bandwidth is for ethernet , we need to consider mpu.

[yutayu]

pi@raspberrypi:~ $ tc -s qdisc show dev eth0 qdisc cake 8006: root refcnt 2 bandwidth 809Kbit besteffort triple-isolate nonat nowash ack-filter-aggressive split-gso rtt 100.0ms atm overhead 10 Sent 51027233 bytes 98603 pkt (dropped 13191, overlimits 207440 requeues 0) backlog 10773b 18p requeues 0 memory used: 96064b of 4Mb capacity estimate: 809Kbit min/max network layer size: 40 / 1478 min/max overhead-adjusted size: 106 / 1643 average network hdr offset: 14

              Tin 0

thresh 809Kbit target 22.3ms interval 117.3ms pk_delay 124.7ms av_delay 42.9ms sp_delay 7.4ms backlog 10773b pkts 111812 bytes 61481753 way_inds 6963 way_miss 1430 way_cols 0 drops 10575 marks 0 ack_drop 2616 sp_flows 4 bk_flows 8 un_flows 0 max_len 2984 quantum 300

[moeller0]

When settled bandwidth is for internet , so we don't need to set mpu. When settled bandwidth is for ethernet , we need to consider mpu.

You need to set the MPU, if the link you are trying to shape for/on has mpu requirements. Most links like GPON, DOCSIS, PTM do, but ADSL[1|2|2+] as far as I can tell do not. The telltale sign of requiring MPU is if a technology carries the ethernet frame check sequence in its own packages (as that will drag in the ethernet MPU).

[yutayu]

Does that mean it depends on internet connection what I want to shape?

[yutayu]

I got it. Thanks.

[yutayu]

I use pppoa through ethernet. Then my recognization is According to Allowed Packet Lengths of https://wiki.wireshark.org/Ethernet, 0 bytes tcp ack packet costs 46 bytes . Then mpu is 46.

Is this correct?

[yutayu]

or I need to add pppoa overhead 10? mpu 56

or I need to consider ethernet overhead ? mpu 64

[yutayu]

Just my confusing . hold on . Excuse me.

[moeller0]

None of the above ;) For PPPoA over VC/Mux RFC-2364 there is no specific MPU required. The normal ATM cell correction will make sure that 53 is going to be the smallest packet size. So things should just work. BUT really smal packets are typically rare enough that over estimating tad configuring the true MPU will only have a small bandwidth cost and will certainly not causing additional delays.

[yutayu]

PPPoA - LAN - cake PC.

Lowest sending UDP packet size is = 28 ( law data 0bytes + IP header 20bytes+ UDP header 8 bytes ) In the other hand , according to https://wiki.wireshark.org/Ethernet , Ethernet fills 46bytes as maximum. Then padding on ethernet is 18 bytes ( 46 - 28 ), in this case.

Question. We need to consider this 18 bytes on PPP ? If No, This packets costs 1 ATM = 53 bytes ( 48 + 5 ). then I don't set mpu. If Yes, This packets costs 2 ATM = 106 bytes ( 2 ( 48 + 5 ). then I will consider mpu for 2 ATM.

This is my asking.

[yutayu]

https://networkengineering.stackexchange.com/questions/53489/ethernet-padding-value https://tools.wordtothewise.com/rfc/rfc948

  IEEE 802.3 packets have minimum size restrictions based on network
  bandwidth.  When necessary, the data field should be padded (with
  octets of zero) to meet the 802.3 minimum frame size requirements.
  This padding is not part of the IP packet and is not included in
  the total length field of the IP header.

This is asking and answer. Sorry for wasting your time. Thank you very much.

I don't need to set mpu. :)