CRS112x strange issue

mikusk · Fri Aug 02, 2019 6:24 pm

Hi,
I am fighting with this switch whole week. I am new to mikrotik but I think that there is something wrong with my SW.

Default configuration: all ports in one bridge and IP 192.168.88.1 assigned to bridge.

The problem is that only 192.168.88.0/24 can communicate thru the SW. I connected 2 PCs and assign them IP 192.168.11.2 and 192.168.11.3 ping ends with time out. I don't know why if this is just L2 switch it should SW based on MAC and not checking L3 layer.

After I changed computers IPs to 192.168.88.2 and 192.168.88.3 all looks fine and you can see speed test result and all configuration bellow. Please note speed was around 112MB/s and CPU 9%
https://drive.google.com/file/d/1myX-lB ... sp=sharing

Then I add IP 192.168.11.1/24 to the bridge / remove 192.168.88.1 and change computers IPs to 192.168.11.2 and 192.168.11.3. Communication was OK but performance slowed down to 45 MB/s and CPU utilization goes to almost 100%
https://drive.google.com/file/d/1vgetTw ... sp=sharing

I don't know much about RouterOS but this looks for me quite strange nothing changed just IP and boom I lost more than 50% of performance

Could you please recommend me something what can cause this ? Or should I ask for replacement ?

Thanks and regards,
MK

xvo · Sat Aug 03, 2019 11:53 am

It's not "just L2 switch", but also a router at the same time.
Not a powerful one, so when it routes instead of switching, you see a huge performance drop.
Keep that in mind configuring your network.

mikusk · Sat Aug 03, 2019 3:09 pm

Hi,

I know that it can be configured as router, but if you look at the links my configuration is only as l2 switch no routing no fw no vlans and still if i copy file from computers in same subnet so routing is not required I got this performance drop. It looks like for some reason it is hitting cpu but I dont know why

What is even more strange when bridge ip is 192.168.88.1 and all test pc are in this subnet all is good speed is 110MB/s and cpu is 9% when I change bridge ip and test pc to something else i got this performance drop and cpu utilisation.

Nothing changed just:
From:
add address=192.168.88.1/24 interface=bridge network=192.168.88.0

To:
add address=192.168.11.1/24 interface=bridge network=192.168.11.0

Thanks and regards,
MK

Sent from my SM-J530F using Tapatalk

mkx · Sat Aug 03, 2019 5:07 pm

Did you tey to reboot CRS after change of IP? It shouldn't matter, but who knows ...

Does /interface bridge port print show 'H' in flags column for ether and sfp ports?

mikusk · Sat Aug 03, 2019 5:41 pm

Hi,

SW restarted several times it did not help. When I change IP of bridge back to factory default 192.168.88.1/24 and switch both PCs to this subnet speed immediately change from 40 to 110 MB/s and CPU utilization goes down to 9% ...

Here is my configuration nothing changed from default except last line when I change it to:

add address=192.168.11.1/24 interface=bridge network=192.168.11.0

after that switch is starting hitting CPU during copy operation from 192.168.11.11 to 192.168.11.199

/interface bridge
add admin-mac=64:D1:54:FC:99:39 auto-mac=no comment=defconf name=bridge
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
/ip hotspot profile
set [ find default=yes ] html-directory=flash/hotspot
/interface bridge port
add bridge=bridge comment=defconf interface=ether1
add bridge=bridge comment=defconf interface=ether2
add bridge=bridge comment=defconf interface=ether3
add bridge=bridge comment=defconf interface=ether4
add bridge=bridge comment=defconf interface=ether5
add bridge=bridge comment=defconf interface=ether6
add bridge=bridge comment=defconf interface=ether7
add bridge=bridge comment=defconf interface=ether8
add bridge=bridge comment=defconf interface=sfp9
add bridge=bridge comment=defconf interface=sfp10
add bridge=bridge comment=defconf interface=sfp11
add bridge=bridge comment=defconf interface=sfp12
/ip address
add address=192.168.88.1/24 interface=bridge network=192.168.88.0

Here is bridge interfaces status:

#     INTERFACE     BRIDGE     HW  PVID PRIORITY  PATH-COST INTERNAL-PATH-COST    HORIZON
 0 I H ;;; defconf
       ether1        bridge     yes    1     0x80         10                 10       none
 1   H ;;; defconf
       ether2        bridge     yes    1     0x80         10                 10       none
 2   H ;;; defconf
       ether3        bridge     yes    1     0x80         10                 10       none
 3 I H ;;; defconf
       ether4        bridge     yes    1     0x80         10                 10       none
 4 I H ;;; defconf
       ether5        bridge     yes    1     0x80         10                 10       none
 5 I H ;;; defconf
       ether6        bridge     yes    1     0x80         10                 10       none
 6 I H ;;; defconf
       ether7        bridge     yes    1     0x80         10                 10       none
 7 I H ;;; defconf
       ether8        bridge     yes    1     0x80         10                 10       none
 8 I H ;;; defconf
       sfp9          bridge     yes    1     0x80         10                 10       none
 9 I H ;;; defconf
       sfp10         bridge     yes    1     0x80         10                 10       none
10 I H ;;; defconf
       sfp11         bridge     yes    1     0x80         10                 10       none
11 I H ;;; defconf
       sfp12         bridge     yes    1     0x80         10                 10       none

Really appreciate any help ..

Thanks,
MK

mkx · Sat Aug 03, 2019 7:31 pm

How are PCs set-up ... IP address, subnet mask, default gateway? Is there a DHCP server involved or you set them up manually?

xvo · Sat Aug 03, 2019 8:35 pm

Hi,

I know that it can be configured as router, but if you look at the links my configuration is only as l2 switch no routing no fw no vlans and still if i copy file from computers in same subnet so routing is not required I got this performance drop. It looks like for some reason it is hitting cpu but I dont know why

Lack of configuration to properly route the traffic doesn't mean that it won't try to do so anyway.
And that is why you have no connection when CRS subnet ≠ PC's subnet.

Can't say, why moving all the devices to .11. subnet still makes CRS to route instead of switching.

First of all you can try to add a firewall rule dropping everything in forward chain, to completely disable any possible L3 communication between PCs.
Then you can check the configuration on the PC's, to be sure, that you don't specify CRS as default gateway.

But no matter what you will find, your initial network layout with two different subnets coexisting in one broadcast domain is not a proper one.

mikusk · Mon Aug 05, 2019 11:21 am

thank you man

based on your tips I found static route to 192.168.11.0 on one computer probably from some previous testing after route removed everything working fine.
So no strange issue on Mikrotik but my fault I was too concentrate on Mikrotik and forgot to check testing computers.

Now when it is working I will start with VLANs to divide broadcast domains.

Thank you very much for your help.
MK

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