Prioritize management Vlan...

Hi There,

I've written a tool in PHP / javascript for our support guys that measures bandwidth throughput on the Canopy in real time feeding a graph with Json.

Anyway , this works pretty well up until the point when the customer floods his link which causes the script to take much longer then expected to fetch the data via SNMP and ends up giving wrong results.  I am calculating for the time the script takes to fetch the data but the results is always  out when the link is flooded. 

The simplets sollution I can think off is to prioritze the management VLAN so that the script will always have priority when pulling traffic from the interface but this doesn't seems to help much... Well, either that or I blotched it. 

Currently I'm remarking the priority of my Management Vlan to 7 on the  Access point but I can see latency increasing when I flood the Customers link with traffic.  If the above is correct , shouldn't any traffic to the management interface via my Management Vlan be uneffected regardless what the customer does?

Thanks in advance,


Hi Steph,

When you say flooding the link, do you mean you are using all the bandwidth becuase if that is the case then the latency will happen as you are running out of bandwidth.


Hardik Patel

I am assuming that we all have fair understanding of "how network works" at least.Mostly the prioritization here in this case. 

In simple words Prioritization means " Giving importance to one than other",in other words "the fact or condition of being regarded or treated as more important than others".

Consider a scenario where you have traffic A and traffic B and traffic C. You prioritize traffic A as "High", traffic B medium and traffic C low. This actually means during the congestion time in the link (in your words flooding the traffic and making pipe full)the drop level will be like this. 

First drop traffic C (low priority)

Second if needed drop traffic B (medium priority)

Then if still no bandwidth available you may can drop traffic A(high priority).

So setting up the priority doesn't mean that your high priority traffic will not get dropped :) believe me it is "fact".

So what shall we do in such cases ????????????

Well don't worry there is couple of options you can play with something called QoS (Quality Of Service).

So I would highly insist you to "Allocate some amount of bandwidth" to traffic A. So that even if during the high congestion time also only the  traffic C and traffic B will get dropped.But since you have allocated the dedicated bandwidth for traffic A. This will never get dropped. Believe me this is another fact :) .

This is kind of creating a sub-pipe(allocated bandwidth) inside the main pipe (total bandwidth).


Hope  this helps in future as well. All the content/information provided above is based on my own experience and work ability.Please verify it before implementation.

Deepesh Chandra Sharma.
Technical Specialist-L3 Networks.
Cisco Certified Network Professional.
Cambium Certified over PMP/PTP/ePMP.