Ireneusz Szcześniak
2011-Apr-24 15:04 UTC
[Bridge] brctl problem: broadcast doesn't get through
Hi, I'm creating a bridge, and then add to it two tap interfaces. No physical interface is added to the bridge. These are the commands: brctl addbr test ip tuntap add mode tap tap0 ip tuntap add mode tap tap1 ifconfig test up ifconfig tap0 up ifconfig tap1 up brctl addif test tap0 brctl addif test tap1 The problem is that the bridge doesn't seem to work correctly. I sent through tap0 some broadcast frames (WOL frames), and they didn't reach tap1. I was sending packets with: etherwake -b -i tap0 00:00:00:00:00:00 The tshark command for tap0 showed the frames being sent with tap0, but another tshark for tap1 didn't show them. Then I added to tap0 the IP address 192.168.10.1/24, and did: arping 192.168.1.2 I saw ARP request broadcast frames on tap0, but they didn't reach tap1. This is the output of ifconfig for test, tap0, and tap1 interfaces: root at computer:~# ifconfig test test Link encap:Ethernet HWaddr 02:07:b1:eb:2c:2a inet6 addr: fe80::944b:d9ff:fe10:b240/64 Scope:Link UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:19 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:3377 (3.2 KiB) root at computer:~# ifconfig tap0 tap0 Link encap:Ethernet HWaddr 02:07:b1:eb:2c:2a inet addr:192.168.10.0 Bcast:192.168.10.255 Mask:255.255.255.0 inet6 addr: fe80::7:b1ff:feeb:2c2a/64 Scope:Link UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:278 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) root at computer:~# ifconfig tap1 tap1 Link encap:Ethernet HWaddr b2:ee:2c:f9:d5:0d inet6 addr: fe80::b0ee:2cff:fef9:d50d/64 Scope:Link UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:19 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) The output of the brctl: root at computer:~# brctl show bridge name bridge id STP enabled interfaces pan0 8000.000000000000 no test 8000.0207b1eb2c2a no tap0 tap1 root at computer:~# brctl showmacs test port no mac addr is local? ageing timer 1 02:07:b1:eb:2c:2a yes 0.00 2 b2:ee:2c:f9:d5:0d yes 0.00 The output of route: root at computer:/home/iszczesniak# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.2.0 0.0.0.0 255.255.255.0 U 2 0 0 eth1 192.168.10.0 0.0.0.0 255.255.255.0 U 0 0 0 tap0 169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth1 0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth1 What am I doing wrong? Thanks, Irek -- Ireneusz (Irek) Szczesniak http://www.irkos.org
Stephen Hemminger
2011-Apr-24 16:40 UTC
[Bridge] brctl problem: broadcast doesn't get through
On Sun, 24 Apr 2011 17:04:47 +0200 Ireneusz Szcze?niak <irek.szczesniak at gmail.com> wrote:> Hi, > > I'm creating a bridge, and then add to it two tap interfaces. No > physical interface is added to the bridge. These are the commands: > > brctl addbr test > ip tuntap add mode tap tap0 > ip tuntap add mode tap tap1 > ifconfig test up > ifconfig tap0 up > ifconfig tap1 up > brctl addif test tap0 > brctl addif test tap1 > > The problem is that the bridge doesn't seem to work correctly. I sent > through tap0 some broadcast frames (WOL frames), and they didn't reach > tap1. I was sending packets with: > > etherwake -b -i tap0 00:00:00:00:00:00 > > The tshark command for tap0 showed the frames being sent with tap0, > but another tshark for tap1 didn't show them. > > Then I added to tap0 the IP address 192.168.10.1/24, and did: > > arping 192.168.1.2 > > I saw ARP request broadcast frames on tap0, but they didn't reach tap1. > > This is the output of ifconfig for test, tap0, and tap1 interfaces: > > root at computer:~# ifconfig test > test Link encap:Ethernet HWaddr 02:07:b1:eb:2c:2a > inet6 addr: fe80::944b:d9ff:fe10:b240/64 Scope:Link > UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 > RX packets:0 errors:0 dropped:0 overruns:0 frame:0 > TX packets:19 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 txqueuelen:0 > RX bytes:0 (0.0 B) TX bytes:3377 (3.2 KiB) > > root at computer:~# ifconfig tap0 > tap0 Link encap:Ethernet HWaddr 02:07:b1:eb:2c:2a > inet addr:192.168.10.0 Bcast:192.168.10.255 Mask:255.255.255.0 > inet6 addr: fe80::7:b1ff:feeb:2c2a/64 Scope:Link > UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 > RX packets:0 errors:0 dropped:0 overruns:0 frame:0 > TX packets:0 errors:0 dropped:278 overruns:0 carrier:0 > collisions:0 txqueuelen:500 > RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) > > root at computer:~# ifconfig tap1 > tap1 Link encap:Ethernet HWaddr b2:ee:2c:f9:d5:0d > inet6 addr: fe80::b0ee:2cff:fef9:d50d/64 Scope:Link > UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 > RX packets:0 errors:0 dropped:0 overruns:0 frame:0 > TX packets:0 errors:0 dropped:19 overruns:0 carrier:0 > collisions:0 txqueuelen:500 > RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) > > The output of the brctl: > > root at computer:~# brctl show > bridge name bridge id STP enabled interfaces > pan0 8000.000000000000 no > test 8000.0207b1eb2c2a no tap0 > tap1 > root at computer:~# brctl showmacs test > port no mac addr is local? ageing timer > 1 02:07:b1:eb:2c:2a yes 0.00 > 2 b2:ee:2c:f9:d5:0d yes 0.00 > > The output of route: > > root at computer:/home/iszczesniak# route -n > Kernel IP routing table > Destination Gateway Genmask Flags Metric Ref Use Iface > 192.168.2.0 0.0.0.0 255.255.255.0 U 2 0 0 eth1 > 192.168.10.0 0.0.0.0 255.255.255.0 U 0 0 0 tap0 > 169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth1 > 0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth1 > > What am I doing wrong? > > > Thanks, > Irek >00:00:00:00:00:00 is an invalid ethernet address and is always dropped by bridge to be in compliance with standards. Use a real ethernet address, for kernel devices there is a convenience routine to generate a random ethernet address. --
Ireneusz Szcześniak
2011-Apr-25 18:29 UTC
[Bridge] brctl problem: broadcast doesn't get through
Now I think I understand better what is happening in my case. I guess that my configuration can be depicted as follows: application that connects to tap1 | ^ | | | tap1 | intf | | v | bridge "test" | ^ v | tap0 | intf | | | v | application that connects to tap0 The reasoning for the arrows above is as follows: 1. When I send a broadcast frame to tap0 with "etherwake -b -i tap0 00:00:00:00:00:00", this frame doesn't reach the bridge, but it reaches the application connected to the tap0 interface. 2. It seems that the tap0 interface is transparent, i.e. the messages that originate at the bridge and that should be sent to the application that connects to tap0 are not consumed by the tap0 interface. Listening with tcpdump or tshark on tap0 shows these messages. 3. When I send in the application connected to tap0 a frame with the destination address of the tap0 interface, this frame is seen at the bridge. If my reasoning is wrong, please let me know. Thanks. Irek On 24.04.2011 17:04, Ireneusz Szcze?niak wrote:> Hi, > > I'm creating a bridge, and then add to it two tap interfaces. No > physical interface is added to the bridge. These are the commands: > > brctl addbr test > ip tuntap add mode tap tap0 > ip tuntap add mode tap tap1 > ifconfig test up > ifconfig tap0 up > ifconfig tap1 up > brctl addif test tap0 > brctl addif test tap1 > > The problem is that the bridge doesn't seem to work correctly. I sent > through tap0 some broadcast frames (WOL frames), and they didn't reach > tap1. I was sending packets with: > > etherwake -b -i tap0 00:00:00:00:00:00 > > The tshark command for tap0 showed the frames being sent with tap0, but > another tshark for tap1 didn't show them. > > Then I added to tap0 the IP address 192.168.10.1/24, and did: > > arping 192.168.1.2 > > I saw ARP request broadcast frames on tap0, but they didn't reach tap1. > > This is the output of ifconfig for test, tap0, and tap1 interfaces: > > root at computer:~# ifconfig test > test Link encap:Ethernet HWaddr 02:07:b1:eb:2c:2a > inet6 addr: fe80::944b:d9ff:fe10:b240/64 Scope:Link > UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 > RX packets:0 errors:0 dropped:0 overruns:0 frame:0 > TX packets:19 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 txqueuelen:0 > RX bytes:0 (0.0 B) TX bytes:3377 (3.2 KiB) > > root at computer:~# ifconfig tap0 > tap0 Link encap:Ethernet HWaddr 02:07:b1:eb:2c:2a > inet addr:192.168.10.0 Bcast:192.168.10.255 Mask:255.255.255.0 > inet6 addr: fe80::7:b1ff:feeb:2c2a/64 Scope:Link > UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 > RX packets:0 errors:0 dropped:0 overruns:0 frame:0 > TX packets:0 errors:0 dropped:278 overruns:0 carrier:0 > collisions:0 txqueuelen:500 > RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) > > root at computer:~# ifconfig tap1 > tap1 Link encap:Ethernet HWaddr b2:ee:2c:f9:d5:0d > inet6 addr: fe80::b0ee:2cff:fef9:d50d/64 Scope:Link > UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 > RX packets:0 errors:0 dropped:0 overruns:0 frame:0 > TX packets:0 errors:0 dropped:19 overruns:0 carrier:0 > collisions:0 txqueuelen:500 > RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) > > The output of the brctl: > > root at computer:~# brctl show > bridge name bridge id STP enabled interfaces > pan0 8000.000000000000 no > test 8000.0207b1eb2c2a no tap0 > tap1 > root at computer:~# brctl showmacs test > port no mac addr is local? ageing timer > 1 02:07:b1:eb:2c:2a yes 0.00 > 2 b2:ee:2c:f9:d5:0d yes 0.00 > > The output of route: > > root at computer:/home/iszczesniak# route -n > Kernel IP routing table > Destination Gateway Genmask Flags Metric Ref Use Iface > 192.168.2.0 0.0.0.0 255.255.255.0 U 2 0 0 eth1 > 192.168.10.0 0.0.0.0 255.255.255.0 U 0 0 0 tap0 > 169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth1 > 0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth1 > > What am I doing wrong? > > > Thanks, > Irek >-- Ireneusz (Irek) Szczesniak http://www.irkos.org