[a-nsp] VLAN in SNMP Interface Table

[Mike Hammett]

If the first paragraph were true, we'd never have port counters on a switch. 




----- 
Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 

----- Original Message -----

From: "Doug McIntyre" <merlyn at geeks.org> 
To: arista-nsp at puck.nether.net 
Sent: Monday, December 9, 2019 7:36:05 AM 
Subject: Re: [a-nsp] VLAN in SNMP Interface Table 

On Sun, Dec 08, 2019 at 06:02:47PM -0600, Mike Hammett wrote: 
> This looks like it's only on layer 3 interfaces, which doesn't do me a whole lot of good. 


I don't know of any hardware that keeps track of layer-2 VLAN packet 
counts going through the switch. Generally, stats are updated on times 
when switches have to _do_ something. Forwarding along layer-2 is 
usually done in ASICs and the switch doesn't do anything special for 
decoding the VLAN headers. OOTH, doing a layer-3 routing termination 
is doing something, which is where I measure everything, on the 
layer-3 edge. And every type of hardware I touch can monitor that. 

As posted before, if you need this sort of thing, you'll probably have 
to go to sflow type collectors in order to get what you want. Or 
consider making your network do layer-3 VLAN terminations somewhere so 
that you can measure it. 

Perhaps there is some weird EVPN/vxlan setup you could make that the 
switch will have to do punting of traffic out to a VTEP, and you could 
measure those counts, but I have zero experience monitoring such a setup. 

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