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vlan and physical interface counters 3560x

Archil Sokhadze
Level 1
Level 1

HI All,

i am expiriencing following issue on switch ,

vlan interface and physical interface (that is serving for this vlan ) have different input/output counters,

there is only one physical interface in this vlan .

sh int vlan 64

30 second input rate 9000 bits/sec, 9 packets/sec

30 second output rate 0 bits/sec, 0 packets/sec

sh int g0/9

30 second input rate 4412000 bits/sec, 924 packets/sec

30 second output rate 4006000 bits/sec, 689 packets/sec

sh vlan

64   TEST_NET                       active    Gi0/9

5 Replies 5

mahmoodmkl
Level 7
Level 7

Hi,

The outputs u  r seeing is as below.

The first is related the traffic recieved by the SVI and the second is traffic recieved from the device which is connected to that port.

And please clarify whether this switch is doing any intervlan routing.

Thanks

yes its doing inter vlan routing , so normally counters should match i guess.

Hi

I dont think that they should match.

may some expert can put some light on this but i think we need to consider  the traffic which is switched in hardware as well.

Thanks

m.kafka
Level 4
Level 4

Hi Archil,

is Gi0/9 configured as switchport mode access or trunk, and what is the current state, access or trunk (never forget about DTP, dynamic trunking protocol)? What is connected to Gi0/9? A host or a switch resp router?

If Gi0/9 is trunk then the "unexplained packets" could be destined for VLAN1, which is most likely your native VLAN and will be untagged. That could explain, that you see more packets on the physical interface (VLAN1, untagged plus VLAN64, tagged) than on the interfacce Vlan64 (VLAN64 tagged only).

Another possibility is, that the interface is forwarding traffic, which is unrelated to VLAN64, but I can't think of any protocol like CDP, DTP, VTP, LACP etc... that would produce such a high data rate.

But still this concerns me: the high rate, around 4 Mbit/s, produced by around 1000 packets per second. This means the packet size is in average around 500 bytes with around 1000 packets per second. Are you sure you don't have any switching loops? Or maybe its really the simple explanation, trunk with native VLAN1 and lot of traffic destined for VLAN1.

Just a guess, Rgds,

MiKa

mode is access, operational mode is also static access.  this port is connected hp switch (which has only vlan 1) .

normally traffic is quite low, than i am initiating larg traffic flow from internal network (other vlan) and counters are increasing on g0/9 (thats normall)  but not on vlan 64 interface.

same is on internal side, counters of g0/1(in access mode as well) are increasing but for interface vlan72 they are not affected.

scheme is like this

pc---HP--->(g0/1)vlan72(switch)vlan64(g0/9)----HP---->gateway

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