bring the bridge up seems to need this:
auto lan1
allow-hotplug lan1
iface lan1 inet manual
pre-up ifconfig $IFACE up
pre-down ifconfig $IFACE down
auto lan2
allow-hotplug lan2
iface lan2 inet manual
pre-up ifconfig $IFACE up
pre-down ifconfig $IFACE down
auto br0
iface br0 inet static
address 192.168.0.18
netmask 255.255.255.0
bridge_ports lan1 lan2
bridge_fd 5
bridge_stp no
https://www.cyberciti.biz/faq/debian-network-interfaces-bridge-eth0-eth1-eth2/ but also need the “auto …” line
your topic is named issues with nat so i guess the problem exists only if NAT (Masquerading) is used…
ping over nat (my main-router) to cloudflare
--- 1.1.1.1 ping statistics ---
2108 packets transmitted, 2094 received, 0% packet loss, time 2110253ms
rtt min/avg/max/mdev = 35.064/44.800/1070.474/65.431 ms, pipe 2
Not much,but 14 packets lost of 2100
tcpdump on main-router:
[18:03] frank@bpi-r2-e:/var/lib/tftp$ sudo tcpdump -v icmp -i lan0 >/dev/null
tcpdump: listening on lan0, link-type EN10MB (Ethernet), capture size 262144 bytes
^C4022 packets captured
4022 packets received by filter
0 packets dropped by kernel
[18:37] frank@bpi-r2-e:/var/lib/tftp$ uname -r
4.14.78-bpi-r2-main
did tcpdump on ppp0 (may wan where masquerade is setup)
[19:04] frank@bpi-r2-e:/var/lib/tftp$ sudo tcpdump -v icmp -i ppp0 >/dev/null
[sudo] Passwort für frank:
tcpdump: listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 262144 bytes
^C2645 packets captured
2645 packets received by filter
0 packets dropped by kernel
client says
--- 1.1.1.1 ping statistics ---
1046 packets transmitted, 1034 received, 1% packet loss, time 1046582ms
rtt min/avg/max/mdev = 36.604/43.582/1066.369/52.799 ms, pipe 2
you can run (maybe with watch before to see counting)
netstat -i
to see where Packets are dropped, i have indeed some for lan0 which is my main-lan-interface (but there are 25m cable between r2 and switch, which may cause errors)
pinged google-dns over night and this is the result:
--- 8.8.8.8 ping statistics ---
46758 packets transmitted, 46742 received, +4 errors, 0% packet loss, time 46826538ms
rtt min/avg/max/mdev = 10.029/22.975/1042.775/87.433 ms, pipe 2
16 packets lost of 46700 and these are caused for sure by my 24h connection-reset (done by cronjob)