a networking question

[Tapas Mishra]

On Thu, Jan 6, 2011 at 6:39 PM, stan <stanb at panix.com> wrote:
> I have a workstation in my lab with 10.04 on it. I want to create a
> situation where I can atache test devices on various 192.168.x.x subnets to
> one of the switches it is already pluged in to. Taht is I want multiple
> subnets on the smae physcial "wire" Here is what I have put in
> /etc/network/interfaces:
>
> auto lo
> iface lo inet loopback
> address 127.0.0.1
> netmask 255.0.0.0
>
> auto eth0
> iface eth0 inet static
> address 10.209.120.12
> netmask 255.255.255.0
> gateway 10.209.120.1
>
>
> # auto eth1
>
> # iface eth1 inet static
> # address 192.168.1.5
> # netmask 255.255.255.0
>
> # iface eth1 inet static
> # address 192.168.1.6
> # netmask 255.255.255.0
>
> # iface eth1 inet static
> # address xxx.85.106.148
> # netmask 255.255.255.128
>
> auto br0
> iface br0 inet static
> address xxx.85.106.148
> broadcast xxx.85.106.255
> netmask 255.255.255.128
> # gateway xxx.85.106.143
> bridge_ports eth1
> bridge_fd 2.5
>
> auto eth1:0
> iface eth1:0 inet static
> name Ethernet alias LAN card
> address 192.168.100.2
> netmask 255.255.255.0
> broadcast 192.168.100.255
> network 192.168.100.0
>
> auto eth1:1
> auto eth1:1
> iface eth1:1 inet static
> name Ethernet 2nd alias LAN card
> address 192.168.1.11
> netmask 255.255.255.0
> broadcast 192.168.1.255
> network 192.168.1.0
>
> And here is what netstat -rn reports:
>
> stan at plabws1:/etc/network$ netstat -rn
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags   MSS Window  irtt
> Iface
> xxx.85.106.128  0.0.0.0         255.255.255.128 U         0 0          0
> br0
> 192.168.100.0   0.0.0.0         255.255.255.0   U         0 0          0
> eth1
> 10.209.120.0    0.0.0.0         255.255.255.0   U         0 0          0
> eth0
> 192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0
> eth1
> 192.168.122.0   0.0.0.0         255.255.255.0   U         0 0          0
> virbr0
> 169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0
> eth0
> 0.0.0.0         10.209.120.1    0.0.0.0         UG        0 0          0
> eth0
>
> But I cannot ping something on 192.168.1.x What am I doing wrong?
>
You need to enable ip forwarding on the machine where bridge is.
Correct entry for a bridge is as follows

auto lo
iface lo inet loopback

# The primary network interface
auto eth2
iface eth2 inet manual

auto br0
iface br0 inet static
        address 192.168.1.14
        netmask 255.255.255.0
        network 192.168.1.0
        broadcast 192.168.1.255
        gateway 192.168.1.10
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers 192.168.13.2
        dns-search myserver.net
        bridge_ports eth2
        bridge_fd 9
        bridge_hello 2
        bridge_maxage 12
        bridge_stp off

You can not have eth0 and br0 simultaneously at the same time.
The output of brctl show on my machine shows

brctl show
bridge name	bridge id		STP enabled	interfaces
br0		8000.0026b9824238	no		eth2
							vnet0
							vnet1
							vnet2
							vnet3
Paste your outputs on paste.ubuntu.com here it becomes cluttered to read.
-- 
http://mightydreams.blogspot.com