[kamailio/kamailio] do not fragment flag (#1510) - sr-dev

sergey-safarov

24 Apr 2018 24 Apr '18

7:37 p.m.

looks as `do not fragment` flag is applied to TCP transport by default Later will test on default config.

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sergey-safarov

24 Apr 24 Apr

7:38 p.m.

example of INVITE with `do not fragment` flag is enabled [mtu.pcapng.gz](https://github.com/kamailio/kamailio/files/1944306/mtu.pcapng.gz)

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Daniel-Constantin Mierla

25 Apr 25 Apr

4:01 p.m.

Closed #1510.

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Daniel-Constantin Mierla

4:01 p.m.

This is not something done in Kamailio, but more about the tcp/os stack implementation. Usually tcp sends with do not fragment flag set in order to adapt to the largest MTU that can be used on the path. Not aware if this is something that can be configured at OS level, but I checked kamailio tcp code and there is no such flag set.

If you want to discuss more, bring this topic to sr-users, there might be other people that know more about system options/how to tune this.

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sergey-safarov

26 Apr 26 Apr

7:42 a.m.

Thanks Daniel (@miconda) Looks as [this](http://appcrawler.com/wordpress/2014/06/27/net-ipv4-ip_no_pmtu_disc-and-dont...) case descriptions is same

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Daniel-Constantin Mierla

10:24 a.m.

As I get it from that article, then it can be controlled at OS level via:

``` net.ipv4.ip_no_pmtu_disc = 1 ```

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Daniel-Constantin Mierla
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