Subject: Re: Scaling Max IP address limitation

From: David Jones <[email-masked]>
Date: Sun, 24 Jun 2007 19:03:06 -0500

Robert Iakobashvili wrote:
> Hi,
>
>> On Sun, 24 Jun 2007 12:20:01 -0500 David Jones <[email-masked]> 
>> wrote:
>
>> > I am trying to add multiple IP addresses ( v6 ) to my FC7 box on eth0.
>> > But I am hitting a max limit of 4000 IP address . Seems like there 
>> is a
>> > limiting variable in linux kernel (which one? ) that prevents from
>> > adding more IP addresses than 4096. What do I need to change in Linux
>> > kernel  ( and then recompile ) to be able to add more IP addresses 
>> than
>> > 4K addresses per system? ..
>
>
> We are adding tens of thousand IPv4 addresses using netlink interface
> without any problems. The maximum we added was 60K of secondary
> IPv4 addresses. It consumes some memory, however.
>
> We have also added thousands of IPv6. I will try to test, if there is any
> limit for doing it.
>

I am using the "ip add " command looping sequentially up until RTNETLINK 
starts refusing to add more IP addresses. I am using a simple shell 
script to do the trick. One quick fact : If I exhaust 4K addresses on 
one port , then I can not add more IP's  ( v4/v6 alike ) on any port on 
the system. So seems like its a system wide limitation . Tried digging 
through the kernel source code but no luck so far. So definitely need 
pointers in this regard.
How are you adding via Netlink interface ?
Thanks,
-d