dell 1950 / dell powerconnect 6248 and VLANs
misha at cs.nuim.ie
Wed Jun 6 08:25:28 CDT 2007
On 6 Jun 2007, at 11:49, Arjen wrote:
> I am trying to configure vlans on my CentOS 4.5 box on a dell 1950.
> I am
> able to create a vlan on eth1
> eth1 is up but no IP address
> eth1.2 is a vlan interface with address 10.0.0.78 that has set a route
> for 10.0.0.72/255.255.255.248 (shows up in the routing table)
> no iptables or other packet filtering mechanism for the moment
> interface connected to a Dell PowerConnect 6248 to a port that is in a
> configured VLAN on the switch consisting of four switchports. Two
> are connected to the same VLAN on the switch, having IP addresses
> 10.0.0.77 and 10.0.0.76. I have been trying tagged ports in the VLAN
> through the webinterface of the switch.
I am not familiar with Dell PowerConnect switch, but on a Cisco
switches the interface on the switch should be configured as trunk
(i.e. carry all VLANs over it, tagging packets appropriately.
> If I destroy the vlan on the Linux box and set 10.0.0.78 directly
> on the
> NIC and set the VLAN ports on the switch untagged I can reach both
> 10.0.0.77 and 10.0.0.76. If i try to route through the vlan as
> above I cannot. Tcpdump while pinging shows arp requests on the vlan
What you're describing here suggests that interface on the switch is
not going into trunk mode (sorry for uisng Cisco terminologi, I think
it is called 802.1q trunk?)
Can you run tcpdump on eth1 (the one without IP address). I think you
should see the same arp requests. Another thing you can do is to
connect two machiens directly (nic to nic) with a crossover cable and
run tcpdump on the other machine (this should capture packets as seen
by the switch).
does that switch allow mirroring traffic from one interface to the
other? If yes you can avoid using crossover cable and sniff the
traffic this way.
Vanush "Misha" Paturyan
Computer Science Dept.
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