9
4
I'd like to connect two pairs of veth on a linux bridge, and try to ping from one pair to the other, to test the bridge function.
The below script is tested on several machines, some of them work as expected and the others do not.
After some troubleshooting, I've found that:
brctl showstp <br>
tells both ports are in forwarding statebrctl showmacs <br>
shows both local and external macs correctly
Questions:
- Why the bridge won't forward packets? (don't know differencies among those machines)
- Or, how should I keep troubleshooting?
Any suggestions are appreciated.
--
#!/bin/bash
BR=br1
ip link add veth0 type veth peer name veth1
ip link add veth2 type veth peer name veth3
ip link add $BR type bridge
ip netns add ns0
ip netns add ns1
ip link set veth0 netns ns0
ip link set veth2 netns ns1
ip link set veth1 master $BR
ip link set veth3 master $BR
ip link set $BR up
ip link set veth1 up
ip link set veth3 up
ip netns exec ns0 ip link set veth0 up
ip netns exec ns1 ip link set veth2 up
ip netns exec ns0 ip addr add 172.30.0.1/24 dev veth0
ip netns exec ns1 ip addr add 172.30.0.2/24 dev veth2
ip netns exec ns0 ping 172.30.0.2
EDIT
tcpdump -ni br1
shows:
23:23:31.097396 ARP, Request who-has 172.30.0.2 tell 172.30.0.1, length 28
23:23:31.097431 ARP, Reply 172.30.0.2 is-at 9e:47:56:91:34:e6, length 28
23:23:31.097443 IP 172.30.0.1 > 172.30.0.2: ICMP echo request, id 21210, seq 1, length 64
23:23:32.096804 IP 172.30.0.1 > 172.30.0.2: ICMP echo request, id 21210, seq 2, length 64
23:23:33.096803 IP 172.30.0.1 > 172.30.0.2: ICMP echo request, id 21210, seq 3, length 64
ip netns exec ns1 tcpdump -ni veth2
shows
23:33:58.198790 ARP, Request who-has 172.30.0.2 tell 172.30.0.1, length 28
23:33:58.198823 ARP, Reply 172.30.0.2 is-at 9e:47:56:91:34:e6, length 28
^C
The bridge is bridging arp packets but not bridging icmp packets?
you probably don't want to turn off iptables though, the other answer modifies it to allow it to work. – Peter Oehlert – 2020-02-22T17:35:04.917