How I can include big tcp window?

Hi. How I can include big tcp window in OpenWRT?

You add the values to /etc/sysctl.conf


Hi @lleachii ! A question:

What ‘big tcp window’ means in this context ??

Tried to follow the link but is too difficult to me. What kind of speed are we talking about ?

You'd have to ask the OP. I assume bigger than the default.

This has nothing to do with speed (although, a lot people have tried to tweak this settings to do so since early netwokring days).


TCP tuning
Like most modern OSes, Linux now does a good job of [auto-tuning]
tuning/background/#t1) the TCP buffers, but the  
default maximum Linux TCP buffer sizes are too 
small. The following settings are recommended:

So we are talking of TCP buffers that for router machines indirectly affect speed ? Or Am I wrong again ? Your first link was pointing at kernel 2.6 page is there a table where to find how this buffer size evolved with Linux versions or are they always the same ?

I guess, for forwarded traffic this tweaks do nothing? Cause the client machines are using their own tcp window?

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That's right this will only affect traffic to and from the router, not traffic passing through the router, so for example updating the package list or installing packages.

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What about traffic on vlan I mean packets that need to be tagged or untagged ? Do they pass through router or not ? Or it depends on the type of switch in use ?

What does your question have to do with the TCP window?

Tcp window means how many packets an endpoint will send before waiting for acks. Its a behavior of the endpoint not something a router can change. Like the telephone network can't change how long a business conference call goes on.

The TCP window scale option is an option to increase the receive window size allowed in Transmission Control Protocol above its former maximum value of 65,535 bytes. This TCP option, along with several others, is defined in IETF RFC 1323 which deals with long fat networks. Wikipedia

Was thinking first answer to OP link was related to this but the link was describing TCP buffers. So my question was about TCP buffer if I am not wrong !

I’ ll rephrase : does kernel setting for TCP buffers affect tagged packets processing at high bandwidth rate in openwrt based routers ? Is this a meaningful question or am I missing something again ?

Yes it's a good question but no it won't affect a router, since a router works with one packet at a time. Only the endpoints actually work with the full data stream. A router doesn't need memory to hold tens or hundreds of packets and assemble an entire file transfer etc because after it sends off a packet it never needs that packet again

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