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Lollo
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High and unstable ping and disconnections at 5Ghz

Tue Aug 07, 2007 9:32 pm

Hello!

I'm experiencing (as stated in the subject) unstable and high ping times over my radio links. That's a problem since many play online games and they keep crashing because of the latency and the frequent disconnections!

That's my radio topology:

User CPE @ 5Ghz ------> AP Bridge (wlan1) | Bridge WDS (wlan0) ------> Bridge WDS (wlan1) | Bridge WDS (wlan0) ------> Bridge WDS (wlan0) | Internet Gateway (eth0)

I'm using Routerboard R532A as bridge with R52 (5Ghz) radio modules + 19dB antenna. User CPE is a RIC522 The whole radio link is about 8Km.
The bridge radio links have good (IMHO) radio values: -105dBm Noise Floor and ~ +50SNR!

Latency itself keeps randomly floating from 9ms to 88-120ms from user CPE to the Internet Gateway. That's a pretty high value, considering our latency target for the radio link is a stable 10ms! :(

How can I tweak the link to improove its condition? Searching through the forum I've found out that Data Rates negotiation could be causing troubles. I've changed it this way:

Basic Rate: 6Mbps
Data Rate: 6Mbps-18Mbps-36Mbps

But I think that I need to raise Basic Rate and provide just ONE data rate to avoid the unstable ping: is that correct and safe?

One last thing. I know this is a dumb question, but I need to be sure :D If I set my AP Data Rate to 6Mbps ONLY, does that mean that each client can get to 6Mbps or that the WHOLE bandwidth is 6Mbps (the sum of all clients)?

Thank you very much for your replies!
Last edited by Lollo on Tue Aug 14, 2007 9:40 pm, edited 1 time in total.
 
Lollo
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Re: High and unstable ping and disconnections at 5Ghz

Wed Aug 08, 2007 9:53 am

Almost forgot: do you need any more information?
 
boardman
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Re: High and unstable ping and disconnections at 5Ghz

Tue Aug 14, 2007 4:43 am

Almost forgot: do you need any more information?
Have you already "unpluged" your customers from the network and did some btest tests through your link do you have the same performance issues?

If yes you have interference problems. Switch frequencies.

If not some of your customers are "killing" your link, check for broadcast, P2P applications, virus activity, something like that, use filter rules if you can....

And use default on your Data Rates and control BW with queues.

Best

Jorge
 
0ldman
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Re: High and unstable ping and disconnections at 5Ghz

Tue Aug 14, 2007 7:26 am

Is it changing speeds? Try limiting it just to 6mb for a bit, see what happens.
There is a latency hit when going from 6 to 9, 18, 24, etc...

Although with your signal, I don't see why it isn't a steady 54mb.

May be one bad radio causing problems for everyone.
 
Lollo
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Re: High and unstable ping and disconnections at 5Ghz

Tue Aug 14, 2007 9:59 pm

Thank you very much for your replies, they helped me a lot.

As 0ldman said, switching data-rates was part of the issue, since locking it to Basic-Rate 6/36 and Data-Rate 6/36 helped limiting the ping.

Now I'm getting a lot more ping replies near 10ms, but still too many peaks up to 120ms.

I can't understand too why it isn't a steady 54Mb/s, that problem is really driving me crazy. Signal Strength at 54Mbit/s is -50dBm ... and it has the same power at other data-rates :D Is it safe to force my link to work ONLY at 54MBit/s? I mean, setting Basic and Data rate to ONLY 54mbit, w\o 6!

Ah, my radio topology was a bit.. wrong ;) I've updated my first post with the correct topology :o

Now with my whole radio link set to 36Mbps, I made a BW test from AP Bridge to an antenna near the Internet Bridge, and I got something like 14,9Mbit/s with "udp receive"...

Could WDS be an issue for both latency and throughput? I'm also adding some queues on my AP to limit p2p-upload..
 
0ldman
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Re: High and unstable ping and disconnections at 5Ghz

Thu Aug 16, 2007 7:23 am

What is your ACK set at?
 
Lollo
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Re: High and unstable ping and disconnections at 5Ghz

Thu Aug 16, 2007 9:52 am

What is your ACK set at?
Ack Timeout? If that's what you are asking for, it is set to "dynamic". Also, I've noticed that my units reach 100% CPU spikes and, meanwhile, some packets gets lost (and I bet this affects latency too). Should I try to set CPU frequency of my RB532s to 333 instead of 266?
 
Lollo
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Re: High and unstable ping and disconnections at 5Ghz

Thu Aug 16, 2007 8:52 pm

*** buzz *** :) Nobody else experiencing the same issue?
 
Lollo
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Re: High and unstable ping and disconnections at 5Ghz

Sun Aug 19, 2007 2:43 pm

Just a little update: I've changed my network in order to let each unit work with 1 radio module only.

User CPE @ 5Ghz ------> AP Bridge (wlan1) | eth0 ------> eth0 | Bridge WDS (wlan0) ------> Bridge WDS (wlan1) | eth0 ------> eth0 | Bridge WDS (wlan0)------> Bridge WDS (wlan0) | Internet Gateway (eth0)

I'm also planning to enable 2 antennas per unit on my PtP links, one Rx and one Tx, as follows


Bridge 1 Tx (Antenna A) ------> Bridge 2 Rx (Antenna A)
Bridge 1 Rx (Antenna B) ------> Bridge 2 Tx (Antenna B)

Using high-gain Rx antenna dishes. Should this help? I need to increase throughput too, since it looks like traffic is killing my latency as well :|
 
boardman
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Re: High and unstable ping and disconnections at 5Ghz

Sun Aug 19, 2007 6:22 pm

Hi,

I believe you are pointing your energies to the wrong direction,

- If you are planning to use two antennas one for TX and one for RX, then you will have to use Dual-Nstreme, but for dual-nstreme you will need a bigger CPU, I have read some post of people being able to use RB532's to achieve daul-nstreme but according to the manual and to my own personal experience, dual-nstreme is going to top your CPU, you are mentioning it is peaking 100% usage already, so I believe that is going to get worst.

- I believe WDS is not going to work on dual-nstreme

- As I suggested on my first post on this thread, Have you already tried your setup without customers connected? Results?

- Have you checked for Broadcast on your network?

- Do you have ANY kind of filter on your AP's or edge router in order to DROP FORWARDED annoying packets like 135-137 UDP/TCP , TFTP, RPC, NEtbus, backOrifice, excesive pings.?

- Do you have somewhere in your network a way to "control"/drop excesive connections?

- Do you have somewhere in your network a way to "limit"/drop P2P connections?

- Have you tried with a sniffer to "see" what's going on through your links?

There are several things that can be causing this, you need to dig into it, there is no magical solution when this kinf of weird thing starts to happen. But going dual-nstreme on your setup will not solve anything.

And please for all means upgrade to the latest RouterOs version and UPGRADE your Routerboards BIOS and increase CPU speed to highest available there.

Hope this helps you...


Best Regards

Jorge Boardman
 
Lollo
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Re: High and unstable ping and disconnections at 5Ghz

Sun Aug 19, 2007 6:43 pm

- If you are planning to use two antennas one for TX and one for RX, then you will have to use Dual-Nstreme, but for dual-nstreme you will need a bigger CPU, I have read some post of people being able to use RB532's to achieve daul-nstreme but according to the manual and to my own personal experience, dual-nstreme is going to top your CPU, you are mentioning it is peaking 100% usage already, so I believe that is going to get worst.
I kinda solved the 100% peak usage with my new link topology, it looks like WDS with 2 radio modules was overcharging my routerboards :(
- I believe WDS is not going to work on dual-nstreme
Yeah, true that :( But I was thinking to move to a "routed" solution, instead of a WDS based one
- As I suggested on my first post on this thread, Have you already tried your setup without customers connected? Results?
Yes, it is about 6-8ms with some 40ms peaks (randomly).
- Have you checked for Broadcast on your network?
Not really, would you tell me how to? Thank you :)
- Do you have ANY kind of filter on your AP's or edge router in order to DROP FORWARDED annoying packets like 135-137 UDP/TCP , TFTP, RPC, NEtbus, backOrifice, excesive pings.?
Yes, I had that, but I when I had queues or packet marking/filtering rules active on the AP, winbox stopped listing MAC addresses from Winbox login screen :( I had to disable them :( Do you know anything about this?
- Do you have somewhere in your network a way to "control"/drop excesive connections?
Not yet, how much connections per user do you think would be a good value?
- Do you have somewhere in your network a way to "limit"/drop P2P connections?
I'm handling all p2p and bandwidth shaping on my PPPoE server, which is between the end point of my radio link and my internet gateways. I think that's not helping much with radio links, since the control is "too far away" from the AP, don't you think? But still, because of the winbox problem, I can't enable those on the AP.
- Have you tried with a sniffer to "see" what's going on through your links?
A lot of traffic is going on in there :) Do I have to look for something specific?
There are several things that can be causing this, you need to dig into it, there is no magical solution when this kinf of weird thing starts to happen. But going dual-nstreme on your setup will not solve anything.
I was really hoping that doubling bandwidth would help :(
And please for all means upgrade to the latest RouterOs version and UPGRADE your Routerboards BIOS and increase CPU speed to highest available there.

Hope this helps you...

Best Regards

Jorge Boardman
Following some forum user advice, I'm already updating all my equipment's software to latest version (2.9.46)! Most of my bridges/APs are 2.9.35 while many CPEs are 2.9.27 or less!

Ah, what about Routerboard BIOS? So that's a separate thing from RouterOS update, does this REALLY help?

One last thing: all my 532A are at 266Mhz. Do you think would be safe pushing them to 333Mhz?

Thank you very much for your attention and for your help, I really appreciate that.
 
boardman
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Re: High and unstable ping and disconnections at 5Ghz

Sun Aug 19, 2007 7:42 pm

- If you are planning to use two antennas one for TX and one for RX, then you will have to use Dual-Nstreme, but for dual-nstreme you will need a bigger CPU, I have read some post of people being able to use RB532's to achieve daul-nstreme but according to the manual and to my own personal experience, dual-nstreme is going to top your CPU, you are mentioning it is peaking 100% usage already, so I believe that is going to get worst.
I kinda solved the 100% peak usage with my new link topology, it looks like WDS with 2 radio modules was overcharging my routerboards :(
- I believe WDS is not going to work on dual-nstreme
Yeah, true that :( But I was thinking to move to a "routed" solution, instead of a WDS based one

That is a good idea, specially if you have more than a hundred customers.
- As I suggested on my first post on this thread, Have you already tried your setup without customers connected? Results?
Yes, it is about 6-8ms with some 40ms peaks (randomly).
- Have you checked for Broadcast on your network?
Not really, would you tell me how to? Thank you :), please read broadcast, multicast and unicast, ask Mr. Google or Mr. Wikipedia, also do a little research on domain broadcast and MAC domain, on IP networks. (If you route your broadcast domain wil get split into smaller ones, which is good), routing has it's advantages in certain circumstances, but bridging has its own on certain circumstances, its all a matter of planning according to your growth ratio.
- Do you have ANY kind of filter on your AP's or edge router in order to DROP FORWARDED annoying packets like 135-137 UDP/TCP , TFTP, RPC, NEtbus, backOrifice, excesive pings.?
Yes, I had that, but I when I had queues or packet marking/filtering rules active on the AP, winbox stopped listing MAC addresses from Winbox login screen :( I had to disable them :( Do you know anything about this?

mmm check on the mac domain thing mentioned before ....
- Do you have somewhere in your network a way to "control"/drop excesive connections?
Not yet, how much connections per user do you think would be a good value? Well this will depend on the "size" of your customer, but a very rough guess will be around 10-20 connections per PC on your customer's network.
- Do you have somewhere in your network a way to "limit"/drop P2P connections?
I'm handling all p2p and bandwidth shaping on my PPPoE server, which is between the end point of my radio link and my internet gateways. I think that's not helping much with radio links, since the control is "too far away" from the AP, don't you think? But still, because of the winbox problem, I can't enable those on the AP.

First of all IT WILL HELP no matter where it is located in your network, as a matter of facts the P2P transactions are going to be between your customers and the internet, so having those kind of filters @ your gateway definitively will work.

If your winbox can not show MAC address ... mmmh ... make a list and reach your gear thru IP, if you have dhcp make a static bind MAC to IP .
- Have you tried with a sniffer to "see" what's going on through your links?
A lot of traffic is going on in there :) Do I have to look for something specific? Use an external sniffer like Iris or something similar, attach a HUB (not a switch, 'cuse the broadcast domain thing mentioned before) between your network (the part you want to sniff) and look for excesive broadcast packets (255.255.255.255, or , FF:FF:FF:FF:FF:FF)
There are several things that can be causing this, you need to dig into it, there is no magical solution when this kinf of weird thing starts to happen. But going dual-nstreme on your setup will not solve anything.
Please read Mikrotik's WIKI on firewall section, lot of tips and clues there.

I was really hoping that doubling bandwidth would help :(

I doubt it, I believe you DO NOT have a bandwidth problem but if you are in doubt use THE DUDE and measure and graph your bandwidth on a per link basis, ....
And please for all means upgrade to the latest RouterOs version and UPGRADE your Routerboards BIOS and increase CPU speed to highest available there.

Hope this helps you...

Best Regards

Jorge Boardman
Following some forum user advice, I'm already updating all my equipment's software to latest version (2.9.46)! Most of my bridges/APs are 2.9.35 while many CPEs are 2.9.27 or less!

Ah, what about Routerboard BIOS? So that's a separate thing from RouterOS update, does this REALLY help?

NO, the BIOS upgrade is already included into the RouterOSpackage.npk, just after installing the latest version of routerOS, open a new terminal in your winbox go to /system routerboard then issue a print command, and you will see your current BIOS version and the new available version, just issue a upgrade command and ask yes when prompted, that simple it is... it's on the manual. =)

One last thing: all my 532A are at 266Mhz. Do you think would be safe pushing them to 333Mhz?

YES it is completely safe I have several 266's running at 333 w/o a problem, and several 333 running at 400 ....

Thank you very much for your attention and for your help, I really appreciate that.

Best

Jorge -- sorry for my lousy english ... I officially speak spanish ... =)
 
Lollo
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Re: High and unstable ping and disconnections at 5Ghz

Wed Aug 22, 2007 9:18 pm

I just wanted to thank for your precious replies, my link is now pinging 6ms to 12ms, with just some very rare 17ms peaks :)

Bandwidth was/is also a problem, but I'm working on it as well :D
 
boardman
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Re: High and unstable ping and disconnections at 5Ghz

Fri Aug 24, 2007 1:50 am

I just wanted to thank for your precious replies, my link is now pinging 6ms to 12ms, with just some very rare 17ms peaks :)

Bandwidth was/is also a problem, but I'm working on it as well :D

No problem, glad you figure it out....


Jorge

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