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Monitoring traffic over VLAN Interfaces

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I've got a network that has a number of VLAN's on it, one VLAN is used to bridge between two remote locations over a LES circuit and I've been monitoring that VLAN interface and discovered that there isn't much traffic being registered on it. I started to monitor the physical interface and got a much higher amount of traffic being transferred.

I appreciate that when monitoring this vlan (vlan2) on one switch it is only going to register data passing that interface on that switch so I won't see a full picture of traffic on that VLAN but I'm also only monitoring one port on that switch.

In order for clients to get from one network to the other they have to route via this VLAN interface, so I would have expected to see as much traffic entering and leaving the VLAN interface as there is the physical interface.

Any ideas why the figures are so different?

bandwidth physical-interface prtg traffic-graph vlan-interface

Created on Nov 9, 2010 2:22:54 PM by  alienbob (111) 1 1



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It looks like CEF switches the packets rather than them being routed so they don't ever register as having passed the VLAN interface.

Created on Dec 7, 2010 6:20:57 PM by  alienbob (111) 1 1



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