Switch 3750 - Interface VLAN counters

Hello all,

I use MRTG to poll (SNMP) my cisco switches and to graph in/out bandwidth for some specific ports.

I would like to poll a 3750 switch to get in/out bandwidth for some VLAN interfaces. I already do that on 4507 switch and there is no problem. But with my 3750, interface vlan counters seems to be wrong... !?!.

I explain :

My 3750 is a WS-C3750G-12S (12.2(35)SE1), so with 12 mini-gbic interfaces. All the interfaces are in trunk mode.

Example :

-> Interface g1/0/1 accepts vlans 3 and 4

-> Interface g1/0/2 accepts vlans 3 and 5

-> interface g1/0/3 accepts vlans 3 and 6

-> interface g1/0/4 accepts vlans 100 -> outgoing vlan / default route.

-> ...

I 'd like to get in/out statistics for traffic from/to Vlan 3 routed from/to other vlans.

But in/out counters of interface vlan 3 don't seems to be with the right value : I don't go over 1 or 2 packets/s :

---------------------------- Vlan3 is up, line protocol is up Hardware is EtherSVI, address is 001a.a20b.454e (bia 001a.a20b.454e) Internet address is MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set ARP type: ARPA, ARP Timeout 04:00:00 Last input 00:00:01, output 00:00:00, output hang never Last clearing of "show interface" counters never Input queue: 0/75/121/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/40 (size/max) 5 minute input rate 6000 bits/sec, 1 packets/sec 5 minute output rate 1000 bits/sec, 1 packets/sec 6362193 packets input, 2219645443 bytes, 0 no buffer Received 0 broadcasts (1868101 IP multicasts) 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 1696302 packets output, 395717492 bytes, 0 underruns 0 output errors, 0 interface resets 0 output buffer failures, 0 output buffers swapped out


If I do 'sh interface' on the other physical interfaces, I have a lot of trafic and I'm sure that Vlan 3 traffic is aimed to be routed to Vlan 100 (--> internet). And I have the same problem with the interface vlan 100.

So what's wrong.... is there a specific command on the interface to get these statistics ?

Thanks in advance for your help.

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i dont think the 3750 / 3560s support vlan rate stats (or more accurately, stats for L3 interfaces to a VLAN).

however "show int vlan xxx" does show traffic on a 3560 here - v12.2(40)SE, so there is something being collected you should be able to get at.

most SNMP collectors poll the total input / output stats and calc rates themsleves...... so try doing it that way.

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