high interface vlan utilization?

[baselzind]

on my both core switches 6500 WS-SUP720-BASE. the interface vlan for the server vlan is showing high utilization (txload 143/255, rxload 203/255) also only my 2 server interface vlan are showing high utilization and none of my other links do whether it is edge switches or the firewall. does this means i have high intervlan traffic going through these vlans? is it dangerous? how can i reduce it?

[MHM Cisco World]

Mtu mismatch, the vlan have mtu 1500 and forward traffic between two jumbo l2 interface.

Check this point.

[baselzind]

But how do you know it is a mtu mismatch issue? why couldn't it be heavy load? also how come the interface vlan showing high load and not the physical interface?

[MHM Cisco World]

can you share show interface ?

[baselzind]

today the utilization was below 150/255 and I'm monitoring it. However I would like to understand what does interface vlan utilization means? especially that it isn't a physical port? Does it means there is alot of intervlan data going through it? or does all the vlan data go through it regardless if it is an intervlan traffic or not?

[Joseph W. Doherty]

Hmm, I forget what Cisco defaults as to the expected bandwidth of a SVI, but in practice, since it entails all the edge ports of a VLAN (including those not on the same physical device as the SVI), it can be quite a lot.

For example, as you mention a sup720, such might support (w/o fabric blocking) seven 4 port 10g line cards (i.e. 40g per line card slot), or 280 Gbps ingress and egress (w/o considering sup slots).  (Or consider a 6513, with sup2T that supported [also w/o fabric blocking] 80 Gbps on 11 line cards.)

If the SVI doesn't logically consider its bandwidth (about) 280 Gbps, percentage usages will be incorrect.

In theory, as the sup can handle handle all that bandwidth at wire-speed, even 100% utilization, shouldn't be "dangerous" (although, in most Enterprises, very unusual [NB: BTW, in a SP environment, years ago, I did see 8 port Etherchannels, using 10g ports, on 7609s, dropping packets like crazy as there was more than 80 Gbps to transmit.  The physical port drops were of concern, not "utilization" of any related SVI.].)

[baselzind]

so high SVI utilization especially on the server vlan isn't an indication of a major issue I get from you?

[Joseph W. Doherty]

None of which I'm aware.

You also might cross check all the VLAN ports, ingress/egress, sum them up, and see how that compares with the SVI for that VLAN.  (NB:  SVI shouldn't be greater that interface sums, although might be less because interface sums might be higher because of intra-VLAN traffic, i.e. traffic that doesn't use the SVI.)

[baselzind]

all the interfaces in the vlan which are like 9 have like tx/rx 1/255 for 10/255 at most

[Joseph W. Doherty]

tx/rx ratios of 1/255 and/or 10/255, whether on physical interfaces or virtual interfaces, are based on the "bandwidth" the device "believes" the interface has.  For those to be accurate, you need to insure the interface "bandwidths" are accurate too.

Possibly a good chance your SVI's "bandwidth" doesn't accurately reflect the aggregate bandwidth that might pass through it.