Re: [IPFIX] IPFIX export: SNMP versus physical Interface

Brian Trammell <trammell@tik.ee.ethz.ch> Tue, 26 July 2011 13:31 UTC

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From: Brian Trammell <trammell@tik.ee.ethz.ch>
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Date: Tue, 26 Jul 2011 09:29:30 -0400
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References: <4E2EB359.8070309@cisco.com> <20110726131514.GA6421@elstar.local> <4E2EBFEA.7080109@cisco.com>
To: Paul Aitken <paitken@cisco.com>
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Subject: Re: [IPFIX] IPFIX export: SNMP versus physical Interface
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hi Paul,

The intent is clear from your email, but the terminology here seems like it might be implementation-specific; i'd be in favor of the change but it should be clear that:

10/14 are for "interfaces" as the term is most commonly used (I'm not saying that's the right way to say it, need more coffee)

252/253 are for "physical interfaces" in the special case that the physical interface is different than the notional interface.

Speaking of this in terms of interface "virtualization" requires someone to know more about precisely what sort of virtualization...

Cheers,

Brian


On Jul 26, 2011, at 9:23 AM, Paul Aitken wrote:

> Juergen,
> 
>> On Tue, Jul 26, 2011 at 01:30:17PM +0100, Paul Aitken wrote:
>>> Dear IPFIXers,
>>> 
>>> I noticed that the definitions of fields 10 and 14, and fields 252
>>> and 253 are confusingly similar. See below.
>>> 
>>> Cisco uses fields 10 and 14 to export the logical or virtual
>>> interface (eg. SVI, tunnel), while fields 252 and 253 export the
>>> actual physical interface.
>>> 
>>> For example, if we have an SVI configured on a VLAN, the SNMP index
>>> of the SVI would be exported using fields 10 and 14, while the SNMP
>>> index of the physical port in that VLAN would be exported with
>>> fields 252 and 253.
>>> 
>>> So I propose to update fields 10 and 11 to say, "the index of the
>>> logical or virtual interface ...", to contrast with 252 and 253
>>> which say, "The index of a networking device's physical interface
>>> ...".
>> Not sure this is right because if I only have a physical interface and
>> no logical/virtual interfaces, I think I still want to report the
>> physical interface in fields 10 and 11, no? I am not sure why there is
>> actually a need to change something here.
> 
> In this case, physical == logical, so either 10/14 or 252/253 would be correct.
> 
> We've always used 10/14 in this case.
> 
> P.
> 
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