Hello,

using tcp would be an option, as Alex mentioned, if you can control the udp mtu size. The alternative can be also sctp transport, which should be better that tcp. If you have a recent kernel, that could be better. However, I have to say that I haven't seen much use of sctp lately myself, so do a little testing yourself before pushing to production.

Then, looking at the compress option, enhancing gzcompress also for headers should be easy. But I think that it would require sort of encoding at the beginning, to know is an encrypted packet and eventually specify the algorithm for compression. Not sure if such protocol is defined somewhere else and we can reuse it, or we just brew one ourselves.

Actually, the proposal above with gzcompress module would be to make it simpler (as I thought of doing at some point when I sent packages over long distance and narrow band), because that is already possible if you use an embedded scripting language and corex module -- the example there is pretty much what you are looking for:

  * https://www.kamailio.org/docs/modules/stable/modules/corex.html#async.evr.network_io

Cheers,
Daniel

The customary inter-Kamailio solution is jumbo frames (if you control network end-to-end) or TCP.

—

Sent from mobile, with due apologies for brevity and errors.

On Apr 1, 2019, at 10:33 AM, Igor Olhovskiy <igorolhovskiy@gmail.com> wrote:

Hi!

Was looking on some way to compress SIP signalling between internal servers. But found out, there are no some pre-defined or recommended mechanism of doing this.

Yes, I found gzcompress module, but it will help only in case of big body, but not whole message itself. Like in some cases you can have 4-5 RR headers, which is already a lot of info.

What I googled is

1. SigComp
2. Compact Header form

As I found, SigComp is really not widely-used method and it support along opensource SIP servers/PBXes is not documented.

For Compact Header form - is there any way of using Kamailio to compress message this way?

Maybe also there is a way of having some intermediate proxy-layer software, that will gzip/gunzip SIP signalling in realtime?

All of this actually cause info in SIP/SDP grows rapidly, unfortunately MTU size is not.

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Daniel-Constantin Mierla -- www.asipto.com
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