Mininet can't ping from switch (s1) to host (h1-h4)

Question

I'm creating a simple mininet with a simple command like below. I'm using the OpendayLight SDN controller along with 192.168.20.0/24 subnet. Remote controller IP is hosted at 192.168.8.5. It connects with remote, no problem there. The problem is in short I can't ping from switch (s1) to host (h1-h4) and vice-versa.

sudo mn --topo single,4 --controller=remote,ip=controllerIP --switch ovsk,protocols=OpenFlow13

After that I set IP for hosts and default gateway,

h1 ifconfig h1-eth0 192.168.20.5/24
h2 ifconfig h1-eth0 192.168.20.6/24
h3 ifconfig h1-eth0 192.168.20.7/24
h4 ifconfig h1-eth0 192.168.20.8/24

Gateway:

h1 route add default gw 192.168.20.4
h2 route add default gw 192.168.20.4
h3 route add default gw 192.168.20.4
h4 route add default gw 192.168.20.4

I can ping between hosts like below:

mininet> pingall
*** Ping: testing ping reachability
h1 -> h2 h3 h4 
h2 -> h1 h3 h4 
h3 -> h1 h2 h4 
h4 -> h1 h2 h3 
*** Results: 0% dropped (12/12 received)

But can't ping from s1 to h1-h4:

mininet> s1 ping h1
PING 192.168.20.5 (192.168.20.5) 56(84) bytes of data.
^C
--- 192.168.20.5 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2039ms
mininet> s1 ping h2
PING 192.168.20.6 (192.168.20.6) 56(84) bytes of data.
^C
--- 192.168.20.6 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2056ms

And vice-versa:

mininet> h1 ping 192.168.20.4
PING 192.168.20.4 (192.168.20.4) 56(84) bytes of data.
^C
--- 192.168.20.4 ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 1017ms
mininet> h2 ping 192.168.20.4
PING 192.168.20.4 (192.168.20.4) 56(84) bytes of data.
^C
--- 192.168.20.4 ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 1026ms

Dump flows are below: (I've tried chatGPT, other sites and added a few extra later)

badcode@ovs-mininet:~$ sudo ovs-ofctl dump-flows s1 -O OpenFlow13
 cookie=0x2b00000000000025, duration=7194.065s, table=0, n_packets=139, n_bytes=8974, priority=2,in_port="s1-eth1" actions=output:"s1-eth2",output:"s1-eth3",output:"s1-eth4",output:enp0s10,CONTROLLER:65535
 cookie=0x2b00000000000026, duration=7194.065s, table=0, n_packets=111, n_bytes=7734, priority=2,in_port="s1-eth2" actions=output:"s1-eth1",output:"s1-eth3",output:"s1-eth4",output:enp0s10,CONTROLLER:65535
 cookie=0x2b00000000000027, duration=7194.065s, table=0, n_packets=91, n_bytes=6566, priority=2,in_port="s1-eth3" actions=output:"s1-eth1",output:"s1-eth2",output:"s1-eth4",output:enp0s10,CONTROLLER:65535
 cookie=0x2b00000000000028, duration=7194.065s, table=0, n_packets=88, n_bytes=6376, priority=2,in_port="s1-eth4" actions=output:"s1-eth1",output:"s1-eth2",output:"s1-eth3",output:enp0s10,CONTROLLER:65535
 cookie=0x2b00000000000029, duration=7194.065s, table=0, n_packets=858, n_bytes=506220, priority=2,in_port=enp0s10 actions=output:"s1-eth1",output:"s1-eth2",output:"s1-eth3",output:"s1-eth4",CONTROLLER:65535
 cookie=0x0, duration=2990.045s, table=0, n_packets=42, n_bytes=1902, in_port=LOCAL actions=output:enp0s10
 cookie=0x0, duration=2972.128s, table=0, n_packets=144, n_bytes=84960, in_port=enp0s10 actions=LOCAL
 cookie=0x0, duration=2336.855s, table=0, n_packets=0, n_bytes=0, priority=10,in_port=LOCAL actions=output:"s1-eth1",output:"s1-eth2",output:"s1-eth3",output:"s1-eth4"
 cookie=0x0, duration=2392.952s, table=0, n_packets=0, n_bytes=0, priority=10,ip,nw_dst=192.168.20.4 actions=LOCAL
 cookie=0x2a00000000000100, duration=209.469s, table=0, n_packets=0, n_bytes=0, idle_timeout=600, hard_timeout=300, priority=10,dl_src=9a:51:97:ef:7a:22,dl_dst=4a:a9:8d:0a:77:d2 actions=output:"s1-eth4"
 cookie=0x2a00000000000101, duration=209.469s, table=0, n_packets=0, n_bytes=0, idle_timeout=600, hard_timeout=300, priority=10,dl_src=4a:a9:8d:0a:77:d2,dl_dst=9a:51:97:ef:7a:22 actions=output:"s1-eth2"
 cookie=0x2a00000000000108, duration=209.469s, table=0, n_packets=0, n_bytes=0, idle_timeout=600, hard_timeout=300, priority=10,dl_src=9a:51:97:ef:7a:22,dl_dst=46:d8:9c:ed:b6:cb actions=output:"s1-eth3"
 cookie=0x2a00000000000109, duration=209.469s, table=0, n_packets=0, n_bytes=0, idle_timeout=600, hard_timeout=300, priority=10,dl_src=46:d8:9c:ed:b6:cb,dl_dst=9a:51:97:ef:7a:22 actions=output:"s1-eth2"
 cookie=0x2a00000000000110, duration=209.469s, table=0, n_packets=0, n_bytes=0, idle_timeout=600, hard_timeout=300, priority=10,dl_src=d2:d0:60:e4:d5:5e,dl_dst=4a:a9:8d:0a:77:d2 actions=output:"s1-eth4"
 cookie=0x2a00000000000111, duration=209.469s, table=0, n_packets=0, n_bytes=0, idle_timeout=600, hard_timeout=300, priority=10,dl_src=4a:a9:8d:0a:77:d2,dl_dst=d2:d0:60:e4:d5:5e actions=output:"s1-eth1"
 cookie=0x2a00000000000118, duration=209.469s, table=0, n_packets=0, n_bytes=0, idle_timeout=600, hard_timeout=300, priority=10,dl_src=d2:d0:60:e4:d5:5e,dl_dst=46:d8:9c:ed:b6:cb actions=output:"s1-eth3"
 cookie=0x2a00000000000119, duration=209.469s, table=0, n_packets=0, n_bytes=0, idle_timeout=600, hard_timeout=300, priority=10,dl_src=46:d8:9c:ed:b6:cb,dl_dst=d2:d0:60:e4:d5:5e actions=output:"s1-eth1"
 cookie=0x2a0000000000011c, duration=209.468s, table=0, n_packets=2, n_bytes=84, idle_timeout=600, hard_timeout=300, priority=10,dl_src=9a:51:97:ef:7a:22,dl_dst=d2:d0:60:e4:d5:5e actions=output:"s1-eth1"
 cookie=0x2a0000000000011d, duration=209.468s, table=0, n_packets=3, n_bytes=126, idle_timeout=600, hard_timeout=300, priority=10,dl_src=d2:d0:60:e4:d5:5e,dl_dst=9a:51:97:ef:7a:22 actions=output:"s1-eth2"
 cookie=0x2a0000000000011e, duration=209.468s, table=0, n_packets=0, n_bytes=0, idle_timeout=600, hard_timeout=300, priority=10,dl_src=4a:a9:8d:0a:77:d2,dl_dst=46:d8:9c:ed:b6:cb actions=output:"s1-eth3"
 cookie=0x2a0000000000011f, duration=209.468s, table=0, n_packets=0, n_bytes=0, idle_timeout=600, hard_timeout=300, priority=10,dl_src=46:d8:9c:ed:b6:cb,dl_dst=4a:a9:8d:0a:77:d2 actions=output:"s1-eth4"

Ifconfig:

br1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 200.175.2.4  netmask 255.255.255.0  broadcast 200.175.2.255
        inet6 fe80::a00:27ff:fef0:4ada  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:f0:4a:da  txqueuelen 1000  (Ethernet)
        RX packets 24107  bytes 11222188 (11.2 MB)
        RX errors 0  dropped 3995  overruns 0  frame 0
        TX packets 509  bytes 37275 (37.2 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
br2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.3.4  netmask 255.255.255.0  broadcast 192.168.3.255
        inet6 fe80::a00:27ff:fec6:694f  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:c6:69:4f  txqueuelen 1000  (Ethernet)
        RX packets 5511  bytes 1095542 (1.0 MB)
        RX errors 0  dropped 3995  overruns 0  frame 0
        TX packets 215  bytes 18327 (18.3 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet6 fe80::a00:27ff:fec6:694f  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:c6:69:4f  txqueuelen 1000  (Ethernet)
        RX packets 1702  bytes 772901 (772.9 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 9837  bytes 1389222 (1.3 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
enp0s8: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.8.6  netmask 255.255.255.0  broadcast 192.168.8.255
        inet6 fe80::39e4:4849:bea5:6b62  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:9d:0a:a8  txqueuelen 1000  (Ethernet)
        RX packets 369026  bytes 116598716 (116.5 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 361966  bytes 177779457 (177.7 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
enp0s9: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet6 fe80::59bf:89b5:ed9f:8bdd  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:f0:4a:da  txqueuelen 1000  (Ethernet)
        RX packets 21694  bytes 11275929 (11.2 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 8509  bytes 1168325 (1.1 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
enp0s10: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        ether 08:00:27:dc:21:86  txqueuelen 1000  (Ethernet)
        RX packets 1686  bytes 766328 (766.3 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 9125  bytes 1097566 (1.0 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 35718  bytes 5114924 (5.1 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 35718  bytes 5114924 (5.1 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
s1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.20.4  netmask 255.255.255.0  broadcast 192.168.20.255
        inet6 fe80::a00:27ff:fedc:2186  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:dc:21:86  txqueuelen 1000  (Ethernet)
        RX packets 4205  bytes 415946 (415.9 KB)
        RX errors 0  dropped 4057  overruns 0  frame 0
        TX packets 165  bytes 12118 (12.1 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
s1-eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet6 fe80::e0df:c0ff:fe6f:7ab0  prefixlen 64  scopeid 0x20<link>
        ether e2:df:c0:6f:7a:b0  txqueuelen 1000  (Ethernet)
        RX packets 192  bytes 13200 (13.2 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5443  bytes 891826 (891.8 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
s1-eth2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet6 fe80::849d:bbff:fe96:31b1  prefixlen 64  scopeid 0x20<link>
        ether 86:9d:bb:96:31:b1  txqueuelen 1000  (Ethernet)
        RX packets 163  bytes 11870 (11.8 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5471  bytes 893066 (893.0 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
s1-eth3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet6 fe80::1045:58ff:fed5:a307  prefixlen 64  scopeid 0x20<link>
        ether 12:45:58:d5:a3:07  txqueuelen 1000  (Ethernet)
        RX packets 154  bytes 11324 (11.3 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5477  bytes 893198 (893.1 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
s1-eth4: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet6 fe80::3847:ebff:fe19:5487  prefixlen 64  scopeid 0x20<link>
        ether 3a:47:eb:19:54:87  txqueuelen 1000  (Ethernet)
        RX packets 152  bytes 11128 (11.1 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5478  bytes 893304 (893.3 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Routing table and arp:

mininet> s1 route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.8.1     0.0.0.0         UG    100    0        0 enp0s8
192.168.3.0     0.0.0.0         255.255.255.0   U     0      0        0 br2
192.168.8.0     0.0.0.0         255.255.255.0   U     100    0        0 enp0s8
192.168.20.0    0.0.0.0         255.255.255.0   U     0      0        0 s1
200.175.2.0     0.0.0.0         255.255.255.0   U     0      0        0 br1
mininet> h1 route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.20.4    0.0.0.0         UG    0      0        0 h1-eth0
192.168.20.0    0.0.0.0         255.255.255.0   U     0      0        0 h1-eth0
mininet> s1 arp -n
Address                  HWtype  HWaddress           Flags Mask            Iface
192.168.20.4                     (incomplete)                              br1
192.168.8.1              ether   52:54:00:12:35:00   C                     enp0s8
192.168.3.5              ether   08:00:27:87:ff:98   C                     br2
192.168.3.43                     (incomplete)                              br2
192.168.8.5                      (incomplete)                              br1
200.175.2.5                      (incomplete)                              br2
192.168.8.5                      (incomplete)                              s1
192.168.20.5                     (incomplete)                              s1
192.168.8.5              ether   08:00:27:71:5f:7b   C                     enp0s8
192.168.20.6                     (incomplete)                              s1
192.168.3.5                      (incomplete)                              br1
192.168.8.5                      (incomplete)                              br2
192.168.8.3              ether   08:00:27:f6:22:eb   C                     enp0s8
200.175.2.5              ether   08:00:27:ad:25:87   C                     br1
192.168.3.4                      (incomplete)                              br1
mininet> h1 arp -n
Address                  HWtype  HWaddress           Flags Mask            Iface
192.168.20.4                     (incomplete)                              h1-eth0
192.168.20.6             ether   9a:51:97:ef:7a:22   C                     h1-eth0
192.168.20.7             ether   46:d8:9c:ed:b6:cb   C                     h1-eth0
192.168.20.8             ether   4a:a9:8d:0a:77:d2   C                     h1-eth0
mininet>

You can see that the arp resolution says incomplete for s1 (192.168.20.4).

How can I solve the issue and be able to ping from s1 to hosts? I also want to achieve pinging hosts(h1-h4) from other two bridges br1 & br2 (in ifconfig you can see) but s1 isn't pinging so I guess first I need to solve this issue.

Tried port forwarding inside s1:

s1 sysctl net.ipv4.ip_forward=1
s1 sysctl -p

Tried to add explicit flows to handle ARP traffic:

dpctl add-flow s1 -O OpenFlow13 priority=100,arp,actions=output:ALL

Also, to forward ICMP traffic:

dpctl add-flow s1 -O OpenFlow13 priority=100,icmp,actions=output:ALL

Added a flow that matches traffic destined to 192.168.20.4 and forwards it to the LOCAL interface.

dpctl add-flow s1 -O OpenFlow13 priority=10,ip,nw_dst=192.168.20.4,actions=LOCAL

And a flow that forwards traffic from LOCAL (the switch) to the correct host interfaces.

dpctl add-flow s1 -O OpenFlow13 priority=10,in_port=LOCAL,actions=output:s1-eth1,s1-eth2,s1-eth3,s1-eth4

But nothing seems to work.

score 0 · Answer 1 · answered Sep 30 '24 at 06:36

Based on the answer provided here: https://unix.stackexchange.com/a/754593

I first deleted my mininet setup and then tried the exact example and it worked. Then I connected the controller and it stopped working. So, I realized the problem is within the dump-flows. You can see in my earlier output that there's a lot of flow-rules.

So, I disconnected the controller and it started working again, ran sudo ovs-ofctl dump-flows s1 to see the current flow-rule and there was just one simple rule.

So, what I did to fix this, was connected the controller again, then deleted all the flow rules and added the simple rule that I found before connecting the controller.

sudo ovs-ofctl del-flows s1 -O OpenFlow13
# not exactly sure but chatgpt said something about topology that's why I kept it. I'm guessing this rule is for ODL controller to show topology via DLUX or something, will appriciate if someone clarifies it.
sudo ovs-ofctl add-flow s1 "cookie=0x2b00000000000012, priority=100, dl_type=0x88cc, actions=CONTROLLER:65535" -O OpenFlow13  
# this was the rule that I saw without the controller, I guess it's just making all the packets using L2 switching 
sudo ovs-ofctl add-flow s1 " cookie=0x0, priority=0 actions=NORMAL" -O OpenFlow13

So, it's now working, I'm completely new in SDN environments or mininet so this could not be the intended way to fix it but somehow it did. I'll be still open to answers from the experienced people or mistakes in the fix here. Sharing my answer here for any future folks facing the same issue.

Mininet can't ping from switch (s1) to host (h1-h4)

1 Answers1