At 10:24 AM 1/24/2007, you wrote: >Hazelsnitzel wrote: >>Greetings, >>My task leader wants to use a 24-port Cisco Catalyst 2950 in >>conjunction with a Linux box to emulate multiple low-speed links, >>but I am too much of a novice at networking and VLANs to know >>whether his idea is feasible. >>We currently emulate a single low-speed link by interposing a Linux >>box with two NICs between the endpoints on the link. We use the >>Linux box as a bridge and use Linux traffic control (i.e., tc HTB >>or TBF) and "Netem" to emulate link characteristics. Eleven Linux >>boxes would be required to emulate 11 low-speed links. My task >>leader's idea is to use a single "one-armed" Linux box and the >>24-port 2950 to emulate up to 11 links. >>The intranet in our lab uses OSPF and we are not allowed to >>increase the number of router advertisements, so we can't use the >>Linux box as a router. However, if this constraint were removed, I >>assume (#1) that we still couldn't use the Linux box as a router >>because both endpoints of each link are always in the same >>subnet. Is this assumption correct? >>I also assume (#2) that we can't use the Linux box as a bridge. I >>assume that if the traffic emanating from the bridge were simply >>returned to it on a trunked link, it would only forward frames to >>the destination if the source and destination MAC addresses were in >>the same VLAN. >>I would like to know if my two assumptions are correct and whether >>anyone has a suggestion about how to solve this problem. Could it >>be done by developing some custom forwarding software? If so, >>what would be required? > >It can be done. We offer a product based on VLANs and our (non-open-source) >network emulation tool. >I'm not sure if netem can be used in bridge mode though... > >Here's a link to our 48-port network emulator product sheet (we offer other >quantities of ports as well): >http://www.candelatech.com/lanforge_v3/ct970_product.html > >The diagram shows one LANforge machine and one bridge machine, but we can >now do all of this in a single machine for a more efficient use of hardware. > >If you are interested in more information related specifically to LANforge, >please contact me directly (greearb@xxxxxxxxxxxxxxx). > >Thanks, >Ben > > >>Thanks, >>Bob >>_______________________________________________ >>Vlan mailing list >>Vlan@xxxxxxxxxxxxxxx >>http://www.candelatech.com/mailman/listinfo/vlan > > >-- >Ben Greear <greearb@xxxxxxxxxxxxxxx> >Candela Technologies Inc http://www.candelatech.com > >_______________________________________________ >Vlan mailing list >Vlan@xxxxxxxxxxxxxxx >http://www.candelatech.com/mailman/listinfo/vlan Ben, Thanks for your reply. My task leader has already purchased the Catalyst 2950 and a Dell PowerEdge so we need to try to make it work with this hardware. [ Catalyst 2950 ] [ Linux Bridge ]--[eth0]--[trunked]---[ Port 1 ] +-------[eth1]--[trunked]---[ Port 2 ] VLAN 2 [ Port 3 ]---- 192.168.2.3 VLAN 3 [ Port 4 ]---- 192.168.2.4 VLAN 4 [ Port 5 ]---- 192.168.3.3 VLAN 5 [ Port 6 ]---- 192.168.3.4 ..... ..... .......... In this configuration, VLANs 2 and 3 emulate one link and VLANs 4 and 5 emulate another. Will this configuration work? Are there any adverse consequences to having two trunked links as shown? Regards, Bob
