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Build Identifier: 

When an interface goes down/ or unplugged or the device which it is connected
to goes down then the system stops routing traffic between interfaces

On Leap42.1 it has occurred when we add a vlan/ or change network settings

I am also able to simulate it with an
wicked ifdown eth1
wicked ifup eth1

It does not affect any routing that takes place on the box, but only if the
traffic is being forwarded though the box ie from a system connected to eth1 to
a system connected to eth2 it will fail to forward traffic, 

ie system1 - switch1 - [eth1 on machine to eth2 on machine] - switch2 - system2

Restarting or removing firewall rules does not fix it. 

I have found I can get the forwarding to work again by turning forwarding off
and then back on. (The forwarding will show that it is still on before I turn
it off)

ie
cat /proc/sys/net/ipv4/ip_forward
returns a "1"

echo "0" > /proc/sys/net/ipv4/ip_forward

cat /proc/sys/net/ipv4/ip_forward
returns a "0"

echo "1" > /proc/sys/net/ipv4/ip_forward

cat /proc/sys/net/ipv4/ip_forward
returns a "1"

Forwarding works again. (Everything seems back to normal)


Reproducible: Always

Steps to Reproduce:
1. wicked ifdown eth1
2. wicked ifup eth1
3.  (Forwarding stops working - between to outside machines with the affected
machine in the middle)

Actual Results:  
ping from outside machine stops working


Expected Results:  
ping should stop and start again when the interface comes backup

If you reboot the machine all of the routing comes backup

if you stop and start the forwarding it comes backup again