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alis.tommy
Beginner

RSPAN Broadcast, impact network intermitten

HI All,

I've configured RSPAN on the customer network.

The impact is, there's a network intermitten on the customer network.

And the source problem is broadcast traffic from the destination port on the RSPAN.

Is anyone found out broadcast problem while configuring RSPAN?

Thansk

5 REPLIES 5
daniel.dib
Rising star

Not sure what you are trying to say here. RSPAN will mirror traffic, it does not create any traffic in it self. If you are mirroring lots of traffic it will put use on the uplinks though so always consider that.

What's the problem with the broadcast?

Daniel Dib
CCIE #37149

Daniel Dib
CCIE #37149
CCDE #20160011

Please rate helpful posts.

Hi Daniel,

Thanks replying.

I'm mirror source from 10 port on one access switch. All the 10 port is connecting 10 IP Phone and 10 PC.

Then the destination port is Server farm switch on port something.

ip phone and pc ---- access switch --- distribution switch --- core switch --- server farm switch --- server recording

After running for several week, we found out network intermitten on the LAN.

Impact is a lot of request time out on when ping to the interface vlan from client pc (on LAN)

The server monitoring found out, broadcast from the source VLAN RSPAN.

I'm wondering to know what is the source problem here, and way to check it out.

Thanks

So on those 10 ports you have one data VLAN and one voice VLAN? The RSPAN would mirror the broadcast sourcing from those VLANs so if there is excessive broadcast in the RSPAN VLAN that should be sourcing from one of those VLANs.

Can you check those ports if they have a lot of broadcasts in? Do you have STP enabled? Do you have a physical loop? You could have a bridging loop going on but you should see some other symptoms as well then like high CPU on the switches.

The way RSPAN works is that it disables MAC learning so that it can forward the traffic. So if there is a bridging loop that traffic could loop around but I'm not sure that RSPAN is what is causing your issue here.

Daniel Dib
CCIE #37149

Daniel Dib
CCIE #37149
CCDE #20160011

Please rate helpful posts.

So on those 10 ports you have one data VLAN and one voice VLAN? yes it is.

Can you check those ports if they have a lot of broadcasts in?  how to check it.

Do you have STP enabled?  stp is enable, but no physical loop. redundant link all in the shutdown mode to prevent the stp looping issue cause this network intermitten.

but after disable the RSPAN, network became normal.

OK, that seems strange. To see broadcasts on an interface do show interface and look for broadcasts.

Check if your uplinks are using a lot of capacity. Maybe enabling RSPAN put too much load on your uplinks.

It's difficult to diagnose but I've never heard RSPAN cause anything like that, check your version if it has any bugs regarding RSPAN or open a TAC case.

Daniel Dib
CCIE #37149

Daniel Dib
CCIE #37149
CCDE #20160011

Please rate helpful posts.