[prev in list] [next in list] [prev in thread] [next in thread] 

List:       loadbalancing-l
Subject:    Re: AW: [load balancing] Redundany datacenters (TTL=0)
From:       Rob Pickering <rob () rpanetwork ! co ! uk>
Date:       2003-02-25 16:35:34
[Download RAW message or body]


I think the point is that whilst in practice sending out replies with 
very short TTLs is unlikely to break things, it probably doesn't 
*guarantee* convergence in seconds on link failure either.

If you budget for convergence times closer to 10 mins with occasional 
stragglers like big ISP web-caches holding the "old" address for HTTP 
then this is a more reasonable expectation for the technology.

--
    Rob.

--On 25 February 2003 15:30 +0100 Joerg.Fritsch@tesion.de wrote:

> Hello,
>
> on the market there are numerous products (i.e. alternatives to
> BGP) which do WANLink LoadBalancing based on DNS and NAT. Radware
> LinkProof, RainConnect, Nortel WanLinkLB. These products all work
> with very low TTLs and I haven't heared of any big problems yet! I
> think some of the arguments against low TTLs might be esoteric.
>
> However vendors usually recommend TTLs around 60s. You can watch
> such low TTLs when doing
> 'dig a1974.g.akamai.net' or 'dig www.zdf.de' several times. In the
> answer section they have a TTL of 20s which you see decreasing with
> several subsequent dig-commands.
>
> It is kind of interesting ;-)))
>
> --Joerg
> http://www.firewalls-illustriert.de
>
>
> -----Ursprüngliche Nachricht-----
> Von: Anders Marius Jørgensen [mailto:lists@anders-marius.dk]
> Gesendet: Dienstag, 25. Februar 2003 11:12
> An: lb-l@vegan.net
> Betreff: [load balancing] Redundany datacenters (TTL=0)
>
>
> - Whats the Internet / dns community attitude to using a low TTL
> value (e.g 0)
> ____________________
> The Load Balancing Mailing List
> Unsubscribe:    mailto:majordomo@vegan.net?body=unsubscribe%20lb-l
> Archive:        http://vegan.net/lb/archive
> LBDigest:       http://lbdigest.com
> MRTG with SLB:  http://vegan.net/MRTG
> Hosted by:	http://www.tokkisystems.com
>



____________________
The Load Balancing Mailing List
Unsubscribe:    mailto:majordomo@vegan.net?body=unsubscribe%20lb-l
Archive:        http://vegan.net/lb/archive
LBDigest:       http://lbdigest.com
MRTG with SLB:  http://vegan.net/MRTG
Hosted by:	http://www.tokkisystems.com

[prev in list] [next in list] [prev in thread] [next in thread]