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Re: Alternative to BGP-4 for multihoming?

  • From: Dana Hudes
  • Date: Sun Mar 12 17:52:16 2000

Products like the Nortel Accelar 700 do layer 7 redirect.

----- Original Message ----- 
From: "Peter A. van Oene" <[email protected]>
To: <[email protected]>
Sent: Sunday, March 12, 2000 4:44 PM
Subject: Re: Alternative to BGP-4 for multihoming?

> This is great feedback / moderate flaming.  However, consider the
> following.  
> I have only moderate experience with the F5 3DNS & similar products however
> I am familiar with BGP routing.  My client base are high traffic e-commerce
> style (for lack of a better over used marketing term) web sites.  They sit
> on /28's and smaller in some cases.  I'm certainly not going to be
> successful in acquiring ASN's for these people to do proper load balancing
> between multiple ISP's and most major ISP's see little benefit in modifying
> route tables to include our small netblock.  Its these cases I'm concerned
> with.  In my mind, irrespective of the comments on the functionality of DNS
> for this purpose, I see little other choice.
> As a direct FYI, the 3DNS can make fairly intelligent decisions about where
> to direct traffic beyond simply gauging TCP/53 handshake times.  These is
> quite a detailed, informatative interaction that can take place between the
> 3DNS and F5's local load distributor, the BIG-IP.
> That being said, if anyone has better ideas on how to provide for high
> availability to millions of web sites worldwide, please let me know.
> Pete
> *********** REPLY SEPARATOR  ***********
> On 3/12/00 at 1:32 PM Chris Brenton wrote:
> >"Peter A. van Oene" wrote:
> >> 
> >> Essentially, the 3DNS box assumes the DNS entry for the site for which
> the
> >> customer requires multihoming and it intelligently balances traffic
> amongst
> >> any geographically disparate sites.  This allows for high availability.
> >
> >If I'm not mistaken, it accomplishes this in a somewhat obtrusive
> >manner. The box attempts an xfer back to TCP/53 on the querying DNS
> >server. Based on response time, a proper route is chosen. I've seen a
> >lot of posts to Intrusion & GIAC from people who assumed someone was
> >trying enumeration in preparation for an attack, only to find out it was
> >one of these boxes.
> >
> >I also seem to remember a post on GIAC showing Snort traces of one of
> >these boxes actually performing a full xfer if the box was not locked
> >down. Do you use one of these boxes? If so, any idea what happens to the
> >xfer data?
> >
> >Ignoring the argument as to whether its appropriate to attempt xfers on
> >unsuspecting networks, I also see this as being pretty inefficient. A
> >good quantity of sites are now running split DNS so the querying server
> >is not even reachable. This means a fair percentage of the time the load
> >balance attempt will outright fail.
> >
> >Don't see this replacing BGP anytime soon. ;)
> >
> >Chris
> >-- 
> >**************************************
> >[email protected]
> >
> >* Multiprotocol Network Design & Troubleshooting
> >
> >* Mastering Network Security
> >
> -------
> Peter Van Oene
> Senior Systems Engineer