# IPV6 causes slow internet [solved]

## jesnow

I was having problems with the internet being slow on one of my boxes. Then I noticed that somehow

CONFIG_IPV6=y had crept into my .config. Vis Google I noticed some indications that this might be the cause of the problem. 

Is this normal? If so why? Should I just set it to N and recompile?

TIA 

Jon.Last edited by jesnow on Wed Jan 07, 2009 2:15 am; edited 1 time in total

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## GODhack

ipv6 servers are buggy

OR/AND

packets translation from 4 to 6 and backwards adds more lag.

I think best idea is to use IPv4 until the last day this is possible.

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## jonfr

Please post your ifconfig output out. You cannot have IPv6 unless you are connected to a PoP.

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## jesnow

 *jonfr wrote:*   

> Please post your ifconfig output out. You cannot have IPv6 unless you are connected to a PoP.

 

I'm sure I wasn't *using* IPV6, but somehow I would guess that there was code that was checing for it and slowing eveything down. I did compile with CONFIG_IPV6=N and it did go back to normal. If you want to track this down I'm happy to help. I have lots of slow kernels to choose from. 

Cheers

Jon.

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## jonfr

If your IPv6 address is Link, not Global then you don't have a IPv6 address that works on the internet. Also, if you do have IPv6 address and are getting a slow connection. Then your IPv6 connection is problay configured wrong.

Check the Gentoo Linux IPv6 Home router guide.

http://www.gentoo.org/doc/en/ipv6.xml

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## jesnow

 *jonfr wrote:*   

> If your IPv6 address is Link, not Global then you don't have a IPv6 address that works on the internet. Also, if you do have IPv6 address and are getting a slow connection. Then your IPv6 connection is problay configured wrong.
> 
> Check the Gentoo Linux IPv6 Home router guide.
> 
> http://www.gentoo.org/doc/en/ipv6.xml

 

I suspect more likely, I configured IPV6  in the kernel, and nowhere elae, and every net access had to timeout on IPV6  before defaulting to IPV4. I really had nothing configured, and thought I would play with it later. A mistake, I guess. 

Jon.

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## jonfr

It is ok to configure the IPv6 into the kernel, that will give you a lan IPv6 that you can use on your Lan. Please post your ifconfig output so I can help you fix your issue.

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## sedorox

I think the problem is that by configuring IPv6 in the kernel, you're telling applications to look up the IPv6 address first, since you have support for it. Before you didn't have support in the kernel, so the applications just avoided it all together. If you use Firefox, and have IPv6 enabled in your kernel, go to about:config, and search for network.dns.disableIPv6 and set it to true, if it already isn't. See if this helps bring you back to normal speed. If it does, it just means the applications are waiting on the v6 timeout. so you can either leave that, or remove it from the kernel. If you don't ever plan to mess with v6, just remove it from the kernel.

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## jonfr

IPv6 support for programs is set by ufed.

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