Hi Guys,

Its my first MT router. I have started up with factory default config and changed it to fit my requirements.
Factory default is:
1. port WAN, 2,3,4,5 grouped to Switch port.
Firewall NAT srcnat masquerade.

My change: 1. Port WAN Uplink - Bridged to DMZ VLAN
2,3,4,5 Ports - Default untagged traffic, DMZ VLAN


Problem is that traffic from WAN to LAN port is peaks at about 65Mbps, while traffic from LAN to WAN peaks at about 30Mbps.
CPU utilization is not high. (10-20%). - So it's 30% of 100Mbps link rate!
But if I try to reach the server attached to the LAN port of RB750G from distant location results are catastrophic.
In country traffic within 2-3 hop is up to 30Mbps,
European countries 4-8 hops (ping 30) ~6Mbps,
USA California 10+ hops (ping 180) 0.7 Mbps
Australia lot of hops (ping >300) 0.3 Mbps.

This is same on NAT-ed interface and Bridged interface too.
Same tests without MT Router are at least 10 times better; in country traffic are on stable 100Mbps.
Several tests are made with similar results. This one was http download of a 4GB file on a single thread. As additional threads are added performance is growing. So it looks like something is limiting throughput in MT router.

Checked things:
There are no queues defined or any limit applied.
CPU is not overloaded <50%.
Same results in NATed and Bridged mode.
MT Router is attached to a Cisco WS-C3750 and/or Cisco WS-C3550 switch. No difference. No frame/packet errors.
Both sided are in 100Full duplex by auto negotiation. - Changed all possibilities with no/or minor change. Best performance was using 10Mbps Full duplex !!!
After RouterOS downgrade to 4.17 everyting become about 3 times faster in local traffic, but as latency increases performance drop still drastic.
MikroTik BW test in TCP mode drops connection constantly, While in UDP mode (packet size 1500) between two PCs tops at 35 Mbps/ thread.

Please help.

Best regards,
r.

This is a known problem with v5.2

switch back to the latest 4.x firmware and your problem is solved

Thanks,

I agree. Downgrading to 4.17 helps much, but not as much as it should... It's a gigabyte router and it should easily push 100Mbps in bridged mode (since there is no much processing requirement for that). So I still unhappy even with 4.17 with its ~20Mbps/thread upload capability in real WAN environment.

I see demo2.mt.lv already use RouterOS 5.3 and hope this issue fill be fixed in it.

This is a known problem with v5.2

switch back to the latest 4.x firmware and your problem is solved

Is it possible to bridge two ports and achieve nearly wire speed (100Mbps) performance on RB750G? - WAN port should be bridged to a DMZ VLAN in my case. Could you please help?

Bridging goes through the CPU. Use the switch chip instead, that's all in hardware and will be wire speed at a gig.

Thanks for your reply, I would be happy to use switch chip but I can't found how to tag/untag VLAN traffic between WAN port and DMZ VLAN. Can you help me regarding this?

Additionally regardless if it goes through CPU or not specification states it can route up to 560Mbps. Bridging is not more CPU intensive than routing. CPU load is still low and throughput of the router still around 20-30 Mbps. In higher latency network its 2-3 Mbps! It's absolutely unacceptable. If I start upload on multiple threads I'm able to reach 100Mbps without any issue even more 300-400Mbps is reachable too. The question is why is it not able to put whole bandwidth on single thread while there are enough CPU resources?

Bridging goes through the CPU. Use the switch chip instead, that's all in hardware and will be wire speed at a gig.

Benchmark tests for 750G can be found here: http://www.routerboard.com/pdf/routerbo ... _tests.pdf

Mtmx80, please generate and send supout.rif file to support@mikrotik.com if you are experiencing much lower results.
http://wiki.mikrotik.com/wiki/Manual:Su ... utput_File

Thank you,
That's the one what I was researched to decide what to purchase.
Firewall On
Conntrack On
Mode: Bridging (There is no FW nor NAT on bridge)
Small packets: 32.93Mbps 50200 packets
Medium size packets: 199.28Mbps 47000 packets
Large packets: 505.19Mbps 41600 packets

I have div it with 2 due to two way communication and once more with 2 to be sure half of advertised should go for sure....but it doesn't. and its nothing to do with CPU performance. Its bug somewhere in packet processing/forwarding.

I have opened a ticket and sent the support.rif few days ago. I hope this issue is caused by my mistake in configuration and you will be able to pinpoint where it is.

Benchmark tests for 750G can be found here: http://www.routerboard.com/pdf/routerbo ... _tests.pdf

Mtmx80, please generate and send supout.rif file to support@mikrotik.com if you are experiencing much lower results.
http://wiki.mikrotik.com/wiki/Manual:Su ... utput_File

I found out this:

It could be issue with TCP Window sizes. We will probably hear that there is nothing to do with TCP window sizes in MT router, but I think differently. Cisco routers has TCP Wndow size/scaling support too, so there should be a good reason for that.

There is a quite good article on TCP throughput calculation depending on latency (WAN): http://bradhedlund.com/2008/12/19/how-t ... nce-links/
Performance is proportional with window size. It looks like MT blocks window size scaling and that is the reason of bad performance.

Hi guys,

I can confirm that there is huge performance improvement in ROS 5.3 even compared to 4.17. So do not downgrade, it's better to wait few days and upgrade to 5.3.

Life is nice again

So where's the 5.3?

So where's the 5.3?

send email to support.

Hi guys,

I can confirm that there is huge performance improvement in ROS 5.3 even compared to 4.17. So do not downgrade, it's better to wait few days and upgrade to 5.3.

Life is nice again

that's good to hear!

I believe I'm having the same issue with my RB750G - with 4.17 everything was fine. I'm streaming HD videos across my RG750G from one local subnet to another and after upgrading to 5.2 I'm getting terrible performance (haven't done any 'scientific tests' but my video playback it suddenly very choppy.

Could anyone confirm that this is fixed in 5.3 ? Any word on when it is release to the general public ?

I got 5.3 from support and it does indeed seem to fix the issue

Hi guys,

I can confirm that there is huge performance improvement in ROS 5.3 even compared to 4.17. So do not downgrade, it's better to wait few days and upgrade to 5.3.

Life is nice again

Is it also normal in 5.5 or only 5.3?