From: Stephen Hemminger <stephen@networkplumber.org>
To: netdev@vger.kernel.org
Subject: Fw: [Bug 84951] New: 8021q: kernel doesn't take into account ethernet header bytes for received packets
Date: Mon, 22 Sep 2014 09:01:34 -0700 [thread overview]
Message-ID: <20140922090134.3a114531@urahara> (raw)
I am inclined to think this is something that is just an incorrect
user expectation.
Begin forwarded message:
Date: Sun, 21 Sep 2014 11:47:22 -0700
From: "bugzilla-daemon@bugzilla.kernel.org" <bugzilla-daemon@bugzilla.kernel.org>
To: "stephen@networkplumber.org" <stephen@networkplumber.org>
Subject: [Bug 84951] New: 8021q: kernel doesn't take into account ethernet header bytes for received packets
https://bugzilla.kernel.org/show_bug.cgi?id=84951
Bug ID: 84951
Summary: 8021q: kernel doesn't take into account ethernet
header bytes for received packets
Product: Networking
Version: 2.5
Kernel Version: 3.16.1
Hardware: All
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: Other
Assignee: shemminger@linux-foundation.org
Reporter: g.djavadyan@gmail.com
Regression: No
Statistics exported by the kernel for received packets on 802.1q subinterfaces
don't consider Ethernet header bytes (dst MAC, src MAC, type). Statistics for
transmitted packets is not affected. The problem is more prominent on
high-speed links (>100Mb/s), as networking tools (nload, iftop, ...) display
lower bandwidth utilization (>5Mb/s difference) than a report from neighboring
routing device (FreeBSD, Cisco). Also, someone monitoring Linux router
interfaces will find that the router generates more information than it
receives.
Tested on CentOS kernel 2.6.32-431.29.2.el6.x86_64 and vanilla 3.16.1 with
drivers: bnx2, atl1c and igb.
How to reproduce:
1. Create dot1q subinterfaces on two boxes (vconfig add eth0 4040).
2. Assign IP addresses to subinterfaces.
3. Check the connection using ping.
4. Check the output from ifconfig eth0.4040 or 'cat
/sys/class/net/eth0.4040/statistics/rx_{packets,bytes}'.
5. Issue standard 56 byte payload ping using 'ping -c 1 neighboring_ip'.
6. Recheck statistics using step 4.
Expected results:
Received packets value should increase by 1 and received bytes value should
increase by 98.
dst MAC - 6
src MAC - 6
ethertype - 2
IP header - 20
ICMP header - 8
ICMP Payload - 56
Total: 98 bytes.
Actual results:
Received packets value increases by 1 and received bytes value increases by 84
bytes.
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next reply other threads:[~2014-09-22 16:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-22 16:01 Stephen Hemminger [this message]
2014-09-24 14:36 ` Fw: [Bug 84951] New: 8021q: kernel doesn't take into account ethernet header bytes for received packets Vlad Yasevich
2014-09-24 14:45 ` [PATCH] vlan: Fix receive statistics under-reporting Vladislav Yasevich
2014-09-24 15:08 ` Eric Dumazet
2014-09-24 16:45 ` Vlad Yasevich
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