Subject: RE: [IPFIX] Exporint options data packet

From: "Bhuvaneswari R P - TLS ,Chennai" <[email-masked]>
Date: Wed, 2 May 2007 16:37:42 +0530

Sorry, I wanted to ask for netflow exporter only. It was a typo.

I still have a doubt, if the rate at which I should send options
Data should depend on options template sending rate? This applies
To when I select to send options data record on regular basis rather
Than only when they change.

Bhuvana.

-----Original Message-----
From: Paul Aitken [mailto:[email-masked]] 
Sent: Wednesday, May 02, 2007 3:47 PM
To: Bhuvaneswari R P - TLS ,Chennai
Cc: [email-masked]
Subject: Re: [IPFIX] Exporint options data packet

Bhuvana,

> Can anyone inform me at what frequency should a netflow
> Collector send options data packet?

Zero. Collectors receive, they don't send. Exporters send options to 
Collectors.

If the option pertains to data records, then the option should be sent 
before those data records to ensure the collector can decode the 
received data records.

However, if the option data isn't directly related to data records (eg, 
it's system meta-data) then it can be sent whenever you like. Perhaps on

a regular basis, or perhaps only when the information changes.

It also depends on how reliable the transport is and how important the 
data is. ie, the less reliable the transport, the more often you'll want

to send the data.

-- 
Paul Aitken
Cisco Systems Ltd, Edinburgh, Scotland.

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---

From: Paul Aitken <[email-masked]>
Date: Wed, 02 May 2007 12:42:16 +0100

Bhuvana,

> I still have a doubt, if the rate at which I should send options Data
> should depend on options template sending rate?

No.

Send (options) templates enough that the collector can be sure to
interpret the (options) data records.

eg, with fully reliable SCTP, send the template just once. With UDP, you
may wish to send templates many times in different messages.

Send (options) data records when there is information to be conveyed.

> This applies To when I select to send options data record on regular
> basis rather Than only when they change.

If you're sending data regularly but infrequently (say, once per hour) 
you might combine the template export with the data export, especially 
if all the option data fits into a single IPFIX message. But note that 
templates should be sent only once when you're using SCTP.

However, if the options export requires multiple IPFIX messages and you 
have an unreliable transport, the danger is that the first message 
(containing the template) is lost, so the subsequent records cannot be 
decoded.

In this case you may choose to have a more regular template refresh (eg 
every 20 or 30 minutes) to be more confident that any of the options 
data records can be decoded because the collector already has the template.

However, if you're exporting options data very frequently (eg, several 
times per minute) then including the options template every time will 
consume export resource unnecessarily.

---

From: Paul Aitken <[email-masked]>
Date: Wed, 02 May 2007 12:42:16 +0100

Bhuvana,

No.