Spanning tree cost question

[peter.troster]

Hi all,

I did a little network diagram and I am hoping somebody can help.

http://img.photobucket.com/albums/v652/mypersonalpics/f34b1916.jpg

As you can see from my diagram, I have 2 core devices which are 6509's and then connected directly to SW1 and SW4, I have 4 3560's. The switches are daisy chained using cooper. I have reduant links on SW1 and SW4 yet I only want to use the primary link unless it fails switch to the secondary link. For this I am using the command "spanning-tree cost 25" on SW4 and on int g0/3 which faces to R2. With my network monitoring software, I am still seeing traffic coming in (recieve) the g0/3 on SW4 yet not going out. I am wondering if the cost is not set properly or if maybe I am doing it the wrong way all together or maybe if this over 100 mb/sec traffic on the port which is in "blocked" state is normal.

Any help is appreciated.

Thanks

[Jon Marshall]

Peter

So not traffic is being sent to clients via SW4 from the output. I'm assuming that Po1 or Po12 is the interconnect ?

So the question remains what is the traffic. Perhaps you could also look at "sh spanning-tree vlan 500" to make sure that no traffic should be forwarded on the gi1/5 link as well.

If not then it may be worth spanning the port gi1/5 or the port gi0/3 on SW4 to see exactly what is accounting for the traffic.

Jon

[peter.troster]

Hi John,

Yes Po1 is the interconnect from R1 and R2 and I have done sh span vlan 500 across all switches and compared as I previously have with vlan 10 with a co-worker and we see no issues. As per spanning port, a co-worker suggested that to the network admin yet there is limitations to how many we can do and we are currently spanning some ports for more serious issues until tomorrow night so possible tomorrow night I will switch it and sniff some traffic and possible see what is what. My purpose here was that the config was configured properly as I have done the same in lab trying to replicate the same issue and I am not able to and there is zero traffic when using a traffic genorator on the test lab.

Thanks

[Jon Marshall]

Peter

The output of the commands you posted show that blocking is occuring where you want it to and that client mac-addresses are being learnt via R1 so i would say from what we can see you have configured things correctly.

Labs always produce slightly different results

Let me know how you get on if you decide to SPAN the port.

Jon

[peter.troster]

Thanks for the help Jon, I really appreicate it. If I am able to span the port, I will do some more work and let you know of my findings. As for the lab, everything always works as it is suppose to in the labs so this is no different as I have learnt with my little experience.

Thanks again

[contech-nelsong]

Is R1 or R2 the root bridge?

[gianluca2891]

If there is a high level of multicast (or broadcast) traffic in the network, it ma be the incoming one you see on the blocked interface.