Re: Tracking traffic usage at router or switch port?

[Mel Beckman <mel () beckman org>]

The reason there can be a (small) difference between those two test points is encapsulation overhead. If the provider 
is counting traffic that is still in an MPLS envelope, it will count more bytes than it will after the traffic has been 
stripped down to just the Ethernet frame on the switch port. This isn’t a big deal for large packets, but for small 
packets, such as those used for streaming protocol (e.g., VoIP) the percentage of overhead can be as high as 15%.

 -mel

> On Jun 1, 2016, at 10:58 AM, Jason Lee <jason.m.lee () gmail com> wrote:
>
> NANOG Community,
>
> Typically where would you expect a service provider to monitor bandwidth
> usage on your circuits? On the physical switch port interface or on the
> vlan interface at the router? In some of the field testing I've been doing
> there can be a difference in the bandwidth usage on the vlan interface at
> the router vs the physical switch port. Is there any particular reason for
> using one vs the other? Is there an industry best practice for this?
>
> Thanks,
>
> Jason