Linux Ethernet Bridging - Apr 2016 - [Bridge] [PROBLEM] mac address learned on wrong port

On 26.04.2016 18:49, Stephen Hemminger wrote:
> This usualy happens when you either have a loop or packet leaks in from
other port.
Yeah, it looks like a loop, but p2p1 is connected to a production network with 
running MSTP, so I was sure there is no loop, but I have double checked it today
and I'm still sure there is no loop in the net outside of the server. To
make it
super sure I have connected p2p1 to a dead end port (vlan with this one port 
only) on a switch and the effect was the same - container's mac is learned
on p2p1.

Could you explain what you mean by packet leaking in from other port?

I have one more clue:

when I do:

# arping -c1 ip-of-gateway

inside the container, then on host I can observe:

tcpdump -en -i vethV05BAQ ether src host 00:16:3e:aa:aa:66

14:57:17.528848 00:16:3e:aa:aa:66 > ff:ff:ff:ff:ff:ff, ethertype ARP
(0x0806),
length 42: Request who-has 212.14.1.33 tell 212.14.1.42, length 28
14:57:17.528915 00:16:3e:aa:aa:66 > ff:ff:ff:ff:ff:ff, ethertype ARP
(0x0806),
length 60: Request who-has 212.14.1.33 tell 212.14.1.42, length 46

Two packets of same content, but different sizes. Difference is a padding of eth
frame to 64 bytes.

Does it mean something?

-- 
Best regards,
Seweryn Niemiec

On Wed, 27 Apr 2016 15:17:01 +0200
Seweryn Niemiec <ser at man.szczecin.pl> wrote:
> On 26.04.2016 18:49, Stephen Hemminger wrote:
> > This usualy happens when you either have a loop or packet leaks in
from other port.
> 
> Yeah, it looks like a loop, but p2p1 is connected to a production network
with
> running MSTP, so I was sure there is no loop, but I have double checked it
today
> and I'm still sure there is no loop in the net outside of the server.
To make it
> super sure I have connected p2p1 to a dead end port (vlan with this one
port
> only) on a switch and the effect was the same - container's mac is
learned on p2p1.
> 
But you are not running Spanning Tree on your bridge.