Hi. We’ve been using the same topology for our Fast Ethernet network for awhile, it has grown quite a bit lately and we’ve wanted to change it around. We’ve been running into some problems with broadcasts traversing vlan boundaries and we’ve become a tad stumped by this.. Here is an example of what we’re doing with the network.

We’re using Black Diamond 6808 switches by extreme, those switches are connected to Cisco GSR 12000 routers which then connect to the Internet

On the extremes every server is connected to its own vlan, and the upstream connection to the router Is in its own vlan. The extreme is doing layer3 (so all of the IP addresses are routed to the switch)

So the VLAN would look something like this..

192.168.0.0/29 The Server’s IP would be 192.168.0.2 The Black Diamond’s IP would be 192.168.0.1 So the server’s gateway would be .1

We have IP forwarding enabled on all of the VLANs so that the traffic can go from the SERVER’s VLAN to the UPSTREAM’s VLAN.

I realize that there are certain design flaws inherit here, can someone point out a better way to design this, if you have any questions I would be happy to answer them.

Also all of the vlans are untagged in the black diamond, and there is no vlan configuration for them whatsoever in the GSR 12000.  

The basic problem is that once in a blue moon we get problems where something will eat up a great deal of cpu cycles in the switch and its almost always a broadcast storm. (which is supposed to be eliminated by private VLANs.

One idea I had was to use the black diamond as a layer2 switch and then use the GSR to do the routing, but that seems kind of round-about.

Any other ideas?

Also the other question I had was are there any very good either open source or fairly affordable netflow analyzer software packages out there right now?

Thanks,

Andrew