4 mikrotik bridges lower TCP one session throughput

RouterOS General
1

HI,

I have 4 Mikrotik nstreme bridges:
RB1000(bt server)<–>MT (nstreme bridge)<–>MT (nstreme bridge)<–>AP(nstreme ap bridge)<–>CPE-RB411AH(BT client)

From CPE-RB411AH to RB1000 the throughput result (UDP) is 24Mb for DL and UL
From CPE-RB411AH to AP(nstreme ap bridge) the throughput result (TCP) is 22Mb for DL and UL

From CPE-RB411AH to RB1000 the throughput result (TCP) is 22Mb for DL (one session)
From CPE-RB411AH to RB1000 the throughput result (TCP) is 2Mb for UL (one session)
From CPE-RB411AH to RB1000 the throughput result (TCP) is 22Mb for UL (20 sessions)



Mikrotik Software version is 4.11 an all devices.

Can any body help why in one session there is only 2Mb of throughput?

br
TopLek

2

The TCP test has trouble reaching full throughput unless you use several sessions, especially on devices with wimpier CPUs. You may notice the CPU usage on one or both sides go to 100% while its running. We have a hard time fully trusting it as a result.

The UDP test will probably give you a good idea of the full speed the path is capable of if all else is perfect, but won’t as effectively show any problems with delayed, dropped or reordered packets like the TCP test will.

3

This is not a CPU problem. An all devices CPU usage is less than 50%.
The same result are when I’m uploading FTP file. Maximum 2Mbps. The download side is OK (22Mb).

Also latency (icmp) is low.

4

So one session goes 2mbit, but 20 gets 22mbit over the same link in the same direction?

Are there any queues or firewall rules? Or a rate limit in the wireless profiles?

Are you FTPing directly to the routerboard or to something behind it?

5

Yes this is exactly the same direction. Exactly the same devices are forwarding packets.

There is no queues and firewall rules and no rate limit in wireless profiles also.
The Ftp is before RB1000.

The point is that BT test are both side 22Mb TCP (one session) traffic for:
1: AP(nstreme ap bridge)<–>CPE-RB411AH(BT client)
2: RB1000(bt server)<–>AP(nstreme ap bridge)

So in fact the upload and download UDP and download TCP (one session) is about 22Mb to 24Mb

BUT between RB1000(bt server) and CPE-RB411AH(BT client) upload from CPE is only 2Mb.