Thanks Stephen.
Can i attach an interface with IP assigned to it already/statically to a bridge?
So if i understand correctly from your response, i should run dhcpclient on br0 interface to assign IP for the same? and Lets say br0 gets an IP assigned by DHCP-Server as "12.0.0.1".
Now my intention is to assign IP address to the Host(say host1) behind Router-1 using the DHCP-Server running on/behind Router-2 as shown below:
Host1 <------> (eth2)[Router-1](eth1:100.1.1.1) <----------EoGRE Tunnel----->(eth0:100.1.1.254)[Router-2](DHCP-Server)
So i thought Bridging eth2 to eth1 in Router-1 is the only way to achieve the same as i want the dhcp-broadcast packet from Host-1 to get tunneled over EogRE till Router-2. Is this assumption correct? or i am missing something here?
Or i should not assign any IP to eth2 and instead do it in br0 in Router-1?
Any guidance would be very helpful and greatly appreciated.
Thanks,
...Balaji.J
On Tue, Dec 13, 2016 at 11:11 PM, Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx> wrote:
You can't and shouldn't try to do anything that assigns an IP addressOn Tue, 13 Dec 2016 21:13:43 +0530
Balaji J <ping2balaji@xxxxxxxxx> wrote:
> Hi all,
>
> I am trying to setup a bridge with 2 interfaces attached to it in Router-1.
> Interface-1: eth1 ==> EoGRE Tunnel interface(gretap) connecting to another
> Router-2 where DHCP server is running.
> Interface-2: eth2 ==> Trying to use DHCP to assign IP for this eth2
> interface from DHCP-Server running on Router-2.
>
> Basically the setup i am expecting is like:
> (eth2)[Router-1](eth1:100.1.1.1) <----------EoGRE
> Tunnel----->(eth0:100.1.1.254)[Router-2](DHCP-Server)
>
> Following are the setup i did to check the 1st stage to see if the
> dhcp-discover broadcast is going out of Router-1 over EoGRE tunnel or not.
> But i am not able to achieve the same.
>
> Can anyone please let me know what is missing here? Thanks in advance.
>
> Router-1:
> 1) ip link add eogre type gretap local 100.1.1.1 remote 100.1.1.254 ==>
> created gretap with endpoints.
> 2) ip link set eogre up ==> brought the eogre interface up.
> [root@centos]# ifconfig
> eogre Link encap:Ethernet HWaddr 9E:25:FC:54:7F:F2
> inet6 addr: fe80::9c25:fcff:fe54:7ff2/64 Scope:Link
> UP BROADCAST RUNNING MULTICAST MTU:1462 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:0 (0.0 b) TX bytes:492 (492.0 b)
>
> eth1 Link encap:Ethernet HWaddr 08:00:27:3C:FB:14
> inet addr:100.1.1.1 Bcast:0.0.0.0 Mask:255.255.255.0
> inet6 addr: fe80::a00:27ff:fe3c:fb14/64 Scope:Link
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:13 errors:0 dropped:0 overruns:0 frame:0
> TX packets:40 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:1398 (1.3 KiB) TX bytes:4103 (4.0 KiB)
>
> eth2 Link encap:Ethernet HWaddr 08:00:27:5E:7F:83
> BROADCAST MULTICAST MTU:1500 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
> 3) brctl addbr br0 ==> created bridge interface
> 4) brctl addif br0 eogre ==> attach eogre interface to bridge
> 5) brctl addif br0 eth2 ==> attach eth2 interface to bridge
> 6) sysctl -w net.ipv6.conf.eth2.disable_ipv6=1 ==> disable ipv6 in eth2
> just to avoid unwanted ipv6 signalling messages from it.
> 7) ifconfig eth2 up ==> eth2 iface up with no IP in it yet.
> 8) ifconfig eogre up ==> eogre iface up
> 9) ifconfig br0 up ==> Bridge up.
> 10) brctl show ==>
> bridge name bridge id STP enabled interfaces
> br0 8000.0800275e7f83 no eogre
>
> eth2
>
> 11) brctl showstp br0
>
> [root@centos-dev ~]# brctl showstp br0
> br0
> bridge id 8000.0800275e7f83
> designated root 8000.0800275e7f83
> root port 0 path cost 0
> max age 19.99 bridge max age
> 19.99
> hello time 1.99 bridge hello time
> 1.99
> forward delay 14.99 bridge forward delay
> 14.99
> ageing time 299.95
> hello timer 0.50 tcn timer
> 0.00
> topology change timer 0.00 gc timer
> 1.50
> hash elasticity 4 hash max 512
> mc last member count 2 mc init query count 2
> mc router 1 mc snooping 1
> mc last member timer 0.99 mc membership timer
> 259.96
> mc querier timer 254.96 mc query interval
> 124.98
> mc response interval 9.99 mc init query interval
> 31.24
> flags
>
>
> eogre (0)
> port id 0000 state
> forwarding
> designated root 8000.0800275e7f83 path cost 100
> designated bridge 8000.0800275e7f83 message age timer
> 0.00
> designated port 8001 forward delay timer
> 0.00
> designated cost 0 hold timer
> 0.00
> mc router 1
> flags
>
> eth2 (0)
> port id 0000 state
> forwarding
> designated root 8000.0800275e7f83 path cost 4
> designated bridge 8000.0800275e7f83 message age timer
> 0.00
> designated port 8002 forward delay timer
> 0.00
> designated cost 0 hold timer
> 0.00
> mc router 1
> flags
>
> 12) dhclient -i eth2 ==> This command triggers a DHCP-DISCOVER
> broadcast(both l2/l3 broadcast destination addressed) from eth2 and
> initiate ip allocation process.
>
> Now if i capture packets in wireshark in eth1+br0+eogre interface of
> Router-1, i don't see the dhcp-discover packet sent from eth2 interface
> going over EoGRE Tunnel to Router-2.
> But the same DHCP-Discover packet i can see if i capture in eth2
> interface(obvious reason).
>
> Is it not like whatever packets coming in or originating from eth2 will be
> bridged to eogre interface using bridge "br0"?
> I am using kernel 2.6 in CentOS
>
> Can someone please help here?
>
> Regards,
> ...Balaji
to a device that is a member of a bridge. In your case that is eth2.
The correct thing to do is run DHCP client on the bridge device.
