Reporting of network occupancy rate on a per-VLAN basis

[sundoo]

Hello, 

The question is apparently simple. A network is given, consisting of
- 1 network core switch: HP 5500-EI (Layer3) 
- 4 access switches: HP 5120-EI (Layer2)

They are connected in the shape of a star (the core switch in the center)
The task is to measure the occupation rate of this network on a per-VLAN basis. 

[B]For example :[/B] 
To be able to generate statistics like: During the last week - Monday to Sunday - the network occupation with VLAN 10 traffic was 30% and VLAN 60 traffic was 70%.

Could anyone tell if IMC is capable of doing that ? 

Thank you in advance

[Peter_Debruyne]

Hi,

I believe you need to be more specific on the volume question. For instance, if a vlan 10 pc downloads 10GB from a server in vlan 20, do you expect the reporting to show the 10GB for vlan 10, vlan 20 or both vlans ? (if both, the sum of the vlan reports would be more than the actual total traffic).

With default IMC you cannot see this level of detail on the traffic stats, this can be achieved with an sflow collector. The IMC NTA module (extra license) can provide these statistics (eg flows from 10.1.10.0/24 or flows from 10.1.20.0/24 if these would represent your vlans.

Sflow is a standard, so other collectors are supported as well. For the switches you need the EI versions for sflow support, but that seems ok for your setup,

Best regards,Peter

[sundoo]

Hello Peter, 

Thank you for the fast reply. Actually, I think I'll modify my question: 

The network contains several data VLANs (network users) and 3 voice VLANs (VoIP and SIP phones). The objective is to be able to tell what is the overall ratio between Voice and Data traffic. 

For example: 

during last week we had about 80% of Data (Traffic measured on all the data VLANs) and 20% of Voice (traffic measuerd on all the Voice VLANs). 

However, for DATA - we can assume that there is no inter-vlan traffic. (The only traffic is to Internet and to an external datacenter - can be easily measured on the router port leading to the datacenter)

But for VOICE - There are, however, calls between users. (need to measure the traffic from user A to user B within the same voice VLAN). 

I was also thinking about sFlow. But my understaing is that the sFlow can classify traffic only on source or destination IP basis. And it can't analyze the dot1Q tag in the frame (in order to tell which trafic - which VLAN). Is that correct ? 

Thank you anyway. You confirmed my thoughts about sFlow. 

[Peter_Debruyne · Accepted solution]

Hi,

yes sflow is based on src/dst l2/l3/l4, but not the vlan tag. But since each vlan will (typically) have an IP subnet, it should be fairly simple to produce the vlan reports based on the IP information.

When this is just occasional reporting, I have used the accounting feature of the QOS policies in the past to see how much traffic was sent for a given class.

This would be an example:

######################
system-view
 # define classes with vlans
traffic classifier tc-voice operator and
 if-match service-vlan-id 10
traffic classifier tc-data operator and
 if-match service-vlan-id 20

 # define accounting behavior
 # this is for 5120. other switches may require
 # the byte or packets keyword after accounting
traffic behavior tb-accounting
 accounting

 # define qos policy, link class to behavior
qos policy qospol-accounting
 classifier tc-voice behavior tb-accounting
 classifier tc-data behavior tb-accounting

# active qos policy at global level, can also be done at vlan or int
 qos apply policy qospol-accounting global inbound

# verify the results
display qos policy global

  Direction: Inbound

  Policy: qospol-accounting
   Classifier: tc-voice
     Operator: AND
     Rule(s) : If-match service-vlan-id 10
     Behavior: tb-accounting
      Accounting Enable:
        39 (Packets)
   Classifier: tc-data
     Operator: AND
     Rule(s) : If-match service-vlan-id 20
     Behavior: tb-accounting
      Accounting Enable:
        0 (Packets)


# if required, clear statistics ( in user-view)
reset qos policy global

Maybe this can help you already.

Best regards,Peter

[sundoo]

Hey, 

I never thought about implementing this using QoS policies :)

Thanks a lot, I just implemented this solution and it works just great. 

I was wondering, wouldn't there be a way to count the inbound bytes using this mechanism  (not the packets) ? :) This way I could have the exact amount of data that crossed the switch :)

Thanks again for your help

[Peter_Debruyne]

Hi,

the 5120 only supports packet accounting, for the 5500 and 5800 switches you can do byte or packet counting.

So for the 5120 it would be

traffic behavior tb-accounting

 accounting

For the 5500/5800 it would be

traffic behavior tb-accounting

 accounting byte

OR

traffic behavior tb-accounting

 accounting packet

Best regards,Peter

[sundoo]

Hello Peter, 

Thanks for the reply.

I have a couple of 5500 EI with Comware 5.20.99 R2215

And the command accounting byte is not supported. :(

[SWITCH-behavior-tb-accounting]accounting ?
<cr>

Only accounting alone is supported. Isn't it the last version of software ? 

[Peter_Debruyne]

sorry, I must have done that on a 5500-HI, so SI and EI do not support the byte count ...