Hello,

I have some PTP multihop links that doesnt perform well. Seems the bandwith drastically decrease while passing an hop.
The main problem is that if I test 2 point, the throughput is max. If i go throgh 3 hops, it will decrease (like half less each hop).
The things are worst with TCP than UDP.

For example, consider this scenario: From RB-OmniTik to RB2011 i have like 40Mbps. From RB-OmniTik to the first RB 711G-5Hnd v.5.23 I have 7Mbps. Please pay attention that there are no new wireless hop, because the 711G-5Hnd is connected by wire to the RB2011.
BUT if i test the ethernet wired from RB 711G-5Hnd to the RB2011 it performs 98Mbps (!). So there is no a wire issue.

If i test from the RB-OmniTik to the last RB1100H2 i have 7Mbps.

I have tried a lot of configuration and a lot of example found on the forum, but them didn't help:
- upgranding and downgrading ROS versions, I also tested the new 6.7. No difference.
- swap the hardware and use the same hardware for PTP
- swap frequency (there is no noise/interference)
- force the GigE ethernet to 100Mbps without auto-negotiation.
- the nework work using OSPF and MPLS routing. I also tried to put all in bridge, and only L3 routing without MPLS. Same issue.
- I tried to swap the RB2011 with RB750, RB450 and RB1100H2, same issue.

So, i think there is definitelly a bug in ROS in multihop routing or L2 frame forwarding, and the thing are worst where there are nv2/wireless hops.

A REPLY FROM MIKROTIK AND A SERIOUS DEBUG IS NEEDED. Otherwise, I will start to swap my hardware to a new vendor.

Mayby helps this setup other device but is the same config.

http://www.wirelessinfo.be/index.php/mi ... /omnitikpp
Goodluck

already tried, no luck

Try to give the same routeros all devices

Try to give all devices the same routeros, sorry my mistake i posted this twice

Yes very important to upgrade all devices to current 6.6 or 6.7 OS.

Then, have you tryed putting the two wireless PTP links in dual chain mode?

If you can that should increase the tru put.

tried dual chain, single chain (selecting various combination of ht-chain0 ht-chain1). I think to a bug because the problem when passing the wired section as I decribed. But the wired ethernet segment works if you test it from the RB711 ethernet to the RB2011 ethernet.

The single PTP works. They doesn't works and the thrughput decrease if you traverse more than 1 hop.

Have all devices the same routeros now?

Set distance not dynamic but full the distance example 3 km for an 2.6 km link

Have all devices the same routeros now?

Set distance not dynamic but full the distance example 3 km for an 2.6 km link

I will try to set the distance. But, as I said, it seems the problem insn't related to the wireless itself:

A=====>B---->C====>D=====>E

where:
--- means wireless
=== means wired ethernet

a=Omnitik
b=RB SXT-5Hnd
c=RB SXT-5Hnd
d=RB2011
e=RB711G-5Hnd

A to D = 40Mbbs
A to E = 7Mbps
D to E = 98Mbps

why this uge difference from A to E ? the only diffierence is a 2 meter long ethernet cable, that WORKS because D to E is 98Mbps. I expect A to E at least 40Mbps like A to D.

How do you test this link? Using btest or iperf? Remember that these mikrotik devices don't have a very fast CPU and are not able to saturate most links when testing TCP performance using btest.

Hello,

I have some PTP multihop links that doesnt perform well. Seems the bandwith drastically decrease while passing an hop.
The main problem is that if I test 2 point, the throughput is max. If i go throgh 3 hops, it will decrease (like half less each hop).
The things are worst with TCP than UDP.

every hop increase latency that affect throughput. bigger latency equals lower throughput.

- the nework work using OSPF and MPLS routing. I also tried to put all in bridge, and only L3 routing without MPLS. Same issue.
- I tried to swap the RB2011 with RB750, RB450 and RB1100H2, same issue.

you should improve latency at your links. you will have lower lattency when you use nstreme... but its not very stable at mt6.7 like rock as mt3.3 ;(

So, i think there is definitelly a bug in ROS in multihop routing or L2 frame forwarding, and the thing are worst where there are nv2/wireless hops.
A REPLY FROM MIKROTIK AND A SERIOUS DEBUG IS NEEDED. Otherwise, I will start to swap my hardware to a new vendor.

maybe... but on ubiquiti rocket m5 you will have same situation. i had tested it.

i have had these issues too and mikrotik cannot drastic explain loss on multihops.
infact bandwidth test in udp stops working in such scenario.
have had similar ROS on all devices.

A to D = 40Mbbs
A to E = 7Mbps

Set ack-timing on both links but..
You have to set the greatest distance on both links

A to D = example 4 km
A to E = example 6 km

Set ack-timing to 7 km for A to D and for A to E

gringoZ is probably right. Low throughput is often the result of high latency.
Lowering the latency of the link or increasing the TCP window size on the endpoints will probably fix your problems.
What is your speed when testing UDP?

RB 711G-5Hnd to the RB2011 it performs 98Mbps?
this is UDP test what about TCP

gringoZ is probably right. Low throughput is often the result of high latency.
Lowering the latency of the link or increasing the TCP window size on the endpoints will probably fix your problems.
What is your speed when testing UDP?

We've seen this behavior, too. If latency is the problem you should not see it with modern Systems
like windows 8. There are built in mechnisms to increment the tcp window size automaticaly.

We think it has to do with queueing within ROS or may be the lack of ethernet flow control/pause frames.

gringoZ is probably right. Low throughput is often the result of high latency.
Lowering the latency of the link or increasing the TCP window size on the endpoints will probably fix your problems.
What is your speed when testing UDP?

We've seen this behavior, too. If latency is the problem you should not see it with modern Systems
like windows 8. There are built in mechnisms to increment the tcp window size automaticaly.

We think it has to do with queueing within ROS or may be the lack of ethernet flow control/pause frames.

If i'm right,i cannot adjust the window size on an edge router, using the mangle. I think that it is adjustable only by the client or the server, right?

gringoZ is probably right. Low throughput is often the result of high latency.
Lowering the latency of the link or increasing the TCP window size on the endpoints will probably fix your problems.
What is your speed when testing UDP?

We've seen this behavior, too. If latency is the problem you should not see it with modern Systems
like windows 8. There are built in mechnisms to increment the tcp window size automaticaly.

We think it has to do with queueing within ROS or may be the lack of ethernet flow control/pause frames.

If i'm right,i cannot adjust the window size on an edge router, using the mangle. I think that it is adjustable only by the client or the server, right?

Yes. The tcp "window" is at the endpoints of tcp communications. It is the size of all packets which can be transmitted until the Sender stops sending waiting for acknowledgement. It adapts automaticaly on modern systems (Win XP did not). Higher latency needs a bigger window size.

for reducing latency, maybe do I need to switch to legacy 802.11/N for my ptp without use nv2?

If the latency will increase a bit for each hop, how do you use for your multi-hop PTP link to maintain a good throughput?

always nstreme
but problem is, as u describe from Omnitik to RB711G basically u have only one wireless link

This is ur quote "RB 711G-5Hnd to the RB2011 it performs 98Mbps?"
it cant be TCP test, can u do TCP Test

Between the 711 and 2011 is wired, so the test is 98Mbps tcp. Can you use nstreme with dual chain and N? I never tried, but i read that is unstable

Between the 711 and 2011 is wired, so the test is 98Mbps tcp. Can you use nstreme with dual chain and N? I never tried, but i read that is unstable

believe it or not I can never reach 98Mbit TCP test with BTest - from board to board

Yes u can use nstreme on N, its a little slower but nstreme has its own advantages like low latency
in wireless protocol just select nstreme instead of nv2 and on ap-side on wlan u can find Nstreme TAB with more options
u can select dynamic size or best fit -see what is best for u

In addition both RB711G and RB2011 have a giga-bit lan, why are they connected to 100mbits? (except if u dont have giga PoE )

In addition both RB711G and RB2011 have a giga-bit lan, why are they connected to 100mbits? (except if u dont have giga PoE )

because the PoE that is not gigabit

So, I test today some configurations and I will post my results.

I have same problem on my network. But now I think it's related to RB2011.
If I do BT to RB2011, over two wireless NV2 links, I get full throughput. But I get more then 50% lower values if I BT to router which is connected to RB2011 over Ethernet. Both UDP and TCP.
There is a major problem somewhere and I have lots of trouble lately.

I hv tried it across a RB1100 as well. or a 433ah too
It is not specific to rb2011

I have same problem on my network. But now I think it's related to RB2011.
If I do BT to RB2011, over two wireless NV2 links, I get full throughput. But I get more then 50% lower values if I BT to router which is connected to RB2011 over Ethernet. Both UDP and TCP.
There is a major problem somewhere and I have lots of trouble lately.

Can u repeat this test but instead RB2011 put simple switch (t-plink, dlink) , than make another test put RB2011 ethernet ports in switch "mode".

Can u repeat this test but instead RB2011 put simple switch (t-plink, dlink) , than make another test put RB2011 ethernet ports in switch "mode".

I have tried that. IT hardly differs. I have had two set of radios. A to B with Groove Metal and 27 dbi grids. Bandwidth test gave over 60 mbps. Another set of radios Groove metal with 23 dbi grids. Bandwidth test gave over 90 mbps. Both links are almost 25 km and Height from ground 30 mtrs+. Actual bandwidth test from my PC never gave more than 4 mbps from A to D. I had the two Grooves connected to switch port of a RB2011 and then a RB 1100 and a RB750 and a SWITCH as well but all gave similar result.

I replaced the two Grooves (C & D) with a 433AH and two mini PCI cards (dbii) Now I am getting over 10mbps but still I was expecting at least 30 mbps. I do get 30 mbps at the Ethernet drop of the 433ah.

Did anyone find out whats the root cause of this issue as I am experiencing something very similar ?
thanks
Brendan

+1 ?

+1!