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MikroTik App
 
chris84
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Posts: 31
Joined: Tue Mar 27, 2007 12:05 pm
Location: Vienna
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Low throughput of small packets

Thu May 20, 2010 2:41 pm

Hi forum,

one of our customers needs a 20Mbps full-duplex point to point link, in this case nstreme2 (Dual Nstreme) is the way to go. Therefore we use two 433AH rbs with four AR5006X 802.11abg cards and four antennas.
Antenna Type:
Airwin 19 dB (5100 - 5900 MHz)
Horizontal

The link is very good:

Rx Signal Strength: -54 dBm
Tx Signal Strength: -56 dBm

Tx/Rx Rate: 54M/54M

Tx Band: 5580 MHz
Rx Band: 5320 MHz

Framer policy: best fit
Framer limit: 4000
The ros bandwidth test show 40 Mbps if tcp and both is used, which exceeds the needed bandwith.

After some days of testing the customer told us that they had experienced low throughput with small packets (64 bytes). They did their tests with a RFC ethernet tester (EXFO 200).

Does anybody know how we can improve the throughput of small packets?

tnx in advance

chris
 
missinlnk
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Posts: 113
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Re: Low throughput of small packets

Thu May 20, 2010 4:06 pm

Can you define low throughput? What were they seeing? And how are you Mikrotik's configured? Are you routing or bridging? Any other features in use on the router?
 
chris84
newbie
Topic Author
Posts: 31
Joined: Tue Mar 27, 2007 12:05 pm
Location: Vienna
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Re: Low throughput of small packets

Fri May 21, 2010 2:47 pm

They just get ~8 Mbps with 64 bytes framesize.

The rbs bridge the traffic. Connection tracking is turned off and no other special services are on.
 
snowcrash
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Joined: Wed Aug 05, 2009 4:27 am

Re: Low throughput of small packets

Fri May 21, 2010 9:49 pm

I would try turning the framer policy to none. I belive that when it is set to best fit with a size of 4000 it holds all those little 64k packets until it can get as close to 4000 before sending one big packet over the wireless. I have heard of n-streme not working so well on low bandwidth links.
 
Insider
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Re: Low throughput of small packets

Sat May 22, 2010 9:42 am

I would try turning the framer policy to none. I belive that when it is set to best fit with a size of 4000 it holds all those little 64k packets until it can get as close to 4000 before sending one big packet over the wireless. I have heard of n-streme not working so well on low bandwidth links.
No no, i got the answer :). USE HT GUARD INTERVAL: BOTH in nstreme setting.. with N cards. I was bugging around this for a week, finally I found yesterday. Unfortunately nobody from MT did not helped me, I asked twice.
Now I can get over 60 000 packets over link per second. The price is but latency yet as those small fuckers are packed in bigger frame and it takes time to get thru buffer.. (20ms in complete run). This way, you will get full valuable throughput about 52mbit full duplex TCP in SINGLE HT 20MHz or 117 mbit in 40MHz

But... I met another issue I am battling with now.. There is constant PL each 7-8 secs for approx 100ms.
TO omprove trhuput Disable CSMA, use exact size policy and framer as I said
Frequency microwave transvertors, design, development, manufacture
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