Concurrent hits limitation

[Brad Dameron]

There is no way you are doing 5000 full 4-way handshakes a second under
ISC DHCP. We have tested this in the LAB extensively with the fastest
core hardware we could get using RAM disks and even then the most we
ever saw was around 450/second. 2-way handshakes you might see double
that. 
 
Brad Dameron
  

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________________________________

From: dhcp-users-bounces+brad.dameron=clearwire.com at lists.isc.org
[mailto:dhcp-users-bounces+brad.dameron=clearwire.com at lists.isc.org] On
Behalf Of Bunny Singh
Sent: Tuesday, January 19, 2010 6:39 AM
To: dhcp-users at lists.isc.org
Subject: Re: Concurrent hits limitation


Hi, 
 
We are going to update the RAM to 6 gb and no battery backed cache is
configured.
 
> I find it hard to believe that you'll see 5000 DORAs per second,
unless
>all of your clients come online at the same time. Do they?

Right now we have 48000 active clients, and i am wonder what would
happen after the downtime, when lots of hits will come at the same time.
Right now approx 250 concurrent connection (showing in the LB connection
established option) are there for the bootps. 
 
So i just want to know what would be the sizing and the recommendation
as per the Ip database and server specification.
 
Regards
Daljit Singh

--- On Mon, 1/18/10, Bunny Singh <jump2fly82 at yahoo.com> wrote:



	From: Bunny Singh <jump2fly82 at yahoo.com>
	Subject: Re: Concurrent hits limitation
	To: dhcp-users at lists.isc.org
	Cc: sthaug at nethelp.no
	Date: Monday, January 18, 2010, 1:19 PM
	
	
 
 
We are using dynamic DNS update and running two scsi disk on RAID-1. We
are having  IBM X3650 server with 4 gb RAM.
 
How many IP addresses do you have among your 800 subnets? What's your
lease time? What's your *target* for DHCP updates (Request/Ack) per
second?
 
We have around 2, 00,000 Ip's. Our lease time is 4 days, Target hits
(DORA) will be 5000 per second.
 
Actually we are in to IPTV services so clients booting their STB's
several times in a day.
 
Also Please suggest is the server failover for the huge IP database is
good or  we will put the servers (without running failover protocol)
behind the Loadbalance in Active Standby state.
 
Regards
Daljit Singh


--- On Mon, 1/18/10, sthaug at nethelp.no <sthaug at nethelp.no> wrote:



	From: sthaug at nethelp.no <sthaug at nethelp.no>
	Subject: Re: Concurrent hits limitation
	To: dhcp-users at lists.isc.org, jump2fly82 at yahoo.com
	Date: Monday, January 18, 2010, 12:13 PM
	
	
	> I want to know about the limitation in DHCP server. Actually
we are running dhcp on failover mode with 800 subnet and it will be
going to expand.
	>  
	> I need to know how many hits (concurrent connections) dhcp
services can handle..
	
	Heavily dependent on your disk subsystem. Also on whether you
use dhcpd
	to perform dynamic DNS updates.
	
	Handling DHCP requests is *disk intensive*. A good RAID
subsystem with
	lots of battery backed cache, or a solid state disk, will do
wonders.
	

	How many IP addresses do you have among your 800 subnets? What's
your
	lease time? What's your *target* for DHCP updates (Request/Ack)
per
	second?
	
	Steinar Haug, Nethelp consulting, sthaug at nethelp.no
<http://us.mc450.mail.yahoo.com/mc/compose?to=sthaug@nethelp.no> 
	



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