I have seen a similar thing. If you do a speed test using RouterOS built-in
test try changing the packet size to 200-300. As far as I can tell, this is
a truer representation of normal internet traffic and does drop the
throughput considerably.

M3P is a good way around this as it will aggregate all the small packets
into a 1500byte packet. I have run the test using 200-300 byte packets on a
M3P link and it gives similar results to a 1500byte test (i.e. full
throughput). There is of course always a down side. With M3P it will wait up
to 15ms to fill that 1500byte packet and therefore adds delay. The impact of
this is that if you normally ping across a link with 1-2ms you will now get
+30ms (15ms on sending the ping and another 15ms on the reply) but when
there is traffic on the link this delay reduces as the 1500byte payload is
being filled quicker.

I have posted a request to Mikrotik to make M3P's 15ms timer user
configurable as I think a delay of 5ms should be plenty to fill the 1500byte
payload during heavy traffic whilst the feature isn't really necessary
during quiet periods. As per normal, I am yet to get any response from MT :(

Give it a go and let us know if it helps.

Cheers,

P.

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of David E. Smith
Sent: 28 October 2005 18:45
To: wireless@wispa.org
Subject: [WISPA] Real-world RouterOS tuning (or, Atheros/RB532 redux)

Okay, I'm a bit puzzled here, and since there are a few folks out there 
playing with these, maybe you'll have some advice.

I just put up a pair of RouterBoard 532s for a heavily-trafficked 
backhaul link. It's about as simple a setup as you can get - just 
Ethernet up to one Atheros, running as an AP, across a 1/2 mile link to 
a client, back down the Ethernet. Simple enough, eh? Since it's just one 
radio hop, I haven't set up WDS or anything fancy, just a few simple 
routing statements to direct traffic from one end to the other.

Using the RouterOS built-in tests, this link claims to be capable of 
almost 40Mbps one-way. I know the tests are somewhat idealized, and 
probably a bit optimistic, but I'm having trouble getting speeds even a 
third of that.

I don't believe it's an RF issue, because it's a short link with good 
antennas. Signal strength is around -58, noise is in the mid-90s. Also, 
when there's no other traffic on the link, I can get the same "test" 
performance there that I was getting on my workbench, where the built-in 
bandwidth tests report 35+ Mbps.

It's just that the darn boards seem to choke in the face of real-world 
traffic. (My real traffic load is around 10Mbps aggregate, balanced 
about 80-20 between upload and download.)

I've tried hopping around to different frequencies, which I didn't 
expect to help. I've tried both enabling and disabling their proprietary 
NStreme protocol, and enabling/disabling radio compression. I haven't 
yet experimented with M3P (the "packet packer protocol" option), but I'm 
a bit skeptical on it as well.

The (informal) testing I've done thus far shows the link not really 
handling traffic beyond about 15Mbps or so. (The "informal" testing was 
done with a few Web-based speed tests. More formal testing, with tools 
like nuttcp or qcheck, will be coming soon, but I'm really skeptical at 
this point.)

Any suggestions on how to further tune the performance on these boards 
would be welcome.

Thanks!

David Smith
MVN.net


-- 
"You don't seem the lying kind... a shame that I can read your mind."
-- 
WISPA Wireless List: wireless@wispa.org

Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless

Archives: http://lists.wispa.org/pipermail/wireless/

-- 
No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.1.362 / Virus Database: 267.12.5/150 - Release Date: 27/10/2005
 

-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.362 / Virus Database: 267.12.5/150 - Release Date: 27/10/2005
 

-- 
WISPA Wireless List: wireless@wispa.org

Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless

Archives: http://lists.wispa.org/pipermail/wireless/

Reply via email to