Mikrotik SXT-5D's In Bridge Mode - Part II

How to Connect two Mikrotik SXT-5D's In Bridge Mode - Part II

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by

JTech

on 04-22-2011 at 04:46 AM (274465 Views)

Setting up the Bridge

To setup the SXT to bridge network traffic do the following to each SXT:

• Click the Bridge button on the left
• Click the Plus button on the menu bar

• Click the STP tab at the top
• Change the “Protocol Mode:” to RSTP
• Click OK

Back at the Bridge window:

• Click the Ports tab at the top
• Click the Plus button on the menu bar
• What defaults in the “New Bridge Port” window is what you want, so click OK. This adds Ether1 to the bridge
• Click the Plus button on the menu bar again.
• Click the “Interface” drop down menu and select Wlan1
• Click Ok

Your Bridge window should look similar to this:



Note: As soon as you finish adding the last bridge your going to get disconnected from one of the SXTs. To get reconnected you’ll need to unplug it from the network switch. They’re still connected wirelessly - Just open WinBox and use the MAC address tool to connect.

Bandwidth Test Between Two Mikrotik SXT-5Ds

I’m not going to cover connecting networks between two SXTs - may be in another post - instead, we’ll make a few changes that will allow us to do a quick bandwidth test. These changes should get you on your way to connecting through the devices as well

First Change the IP address on our client bridge (right SXT) to something else besides 192.168.88.1.

• Click the IP button on the left then Addresses
• Double click on the default address - 192.168.88.1
• Change it to 192.168.88.2 (make sure to leave the /24 in there)
• Click OK

You should now be able to do a bandwidth test.

• WinBox Into the Access Point SXT (Still using the MAC Address Tool)
• Click the Tools button on the left then Bandwidth Test
• Change the “Test To:” field to the address of the client - 192.168.88.2
• Click the “User” field and enter admin for the username
• Click the Start button

Now if you were to test TCP traffic at this point - The results wouldn't be as impressive. This is because you’re relying on the SXT’s to both process and create traffic. This causes a hit to the processor that slows everything down.



Testing through an SXT to a RouterBoard 800 is a different story. Note that you would probably see more...but the SXT only has a 100MB ethernet port.



Getting the most out of your SXT

Now if you really want to push the SXT’s to get the maximum throughput there are a few things to change.

If you haven’t already, you might get as much separation as possible from one SXT to another. In all of the tests below - the SXTs are about 30 feet (10 meters) from each other. This will help their performance.

The first thing we’re going to change is the TX power. With the radios still so close together the signals will to be too high and you’re not going to get the best results.

Do the following to both SXTs:

• Double click on the Wlan1 in the Wireless Tables
• Click the Advance Mode button at the bottom right (If you’re already in advance mode - you’ll see a Simple Mode button instead - don’t click it just go to the next step.)
• Click the TX Power tab
• Click the TX Power Mode list and select All rates fixed
• Now here is where it gets tricky....if the radios are just a few feet away then you shouldn’t have any problems setting the TX Power to 0. The goal here is to lower the TX power until you get the signals to be somewhere between -45 and -60 dB on both sides.

IMPORTANT: Make sure that you change the TX Power settings back to defaults before you unplug your SXT’s and try to deploy them in the field. Otherwise...you’ll be sad.

Now for the additional changes to max everything out. There are a few changes here that have the potential to increase latency, AMPDU Priorities being one of them. I’m not suggesting that you leave these settings in the real world...I’m just showing what is possible.

If you have any questions about these settings, again, hop over to the forum and ask away!

Make the following changes on both sides *beginning with the client first*.

• Double click on the Wlan1 interface in the Wireless Tables
• Click the Advance Mode button at the bottom right (If you’re already in advance mode - you’ll see a Simple Mode button instead - don’t click it just go to the next step.)
• Click the HT tab
• Set “HT Guard Interval” to long
• Click the “HT Extension Channel” list and select Above Control
• Select all 7 Options under “HT AMPDU Priorities”

With the new settings our UDP Bandwidth test looks like this.



And testing Both ways



If you have any questions or suggestions or nitpicks or whatever...I’d be glad to help you out over in the forum