I have been having some issues with my RB751u-2HnD, and have been doing some testing and narrowed it down to the wireless interface/wireless security settings. I have another thread about the issues here, but I wanted to ask the wireless experts.

The issue is if I use Skype (video call) from a Macbook or Macbook Air, the Mikrotik CPU jumps to 100% (mainly the 'flash') process, and then either reboots itself or blocks access from all other machines (web access, SNMP queries, Winbox access). This makes it very difficult to send a supout file. This behaviour ONLY happens on wireless; if I use Skype from the same Macbook using a direct wired ethernet connection, the CPU use is negligible. But if I connect via wireless, setup a Skype video call to a user external to the LAN, the CPU will max out.

I have done all the troubleshooting I can, except using netinstall to do a clean install, as I don't have any Windows machines to run the software. I have upgraded the firmware (to 2.38), and I have upgraded through from RouterOS 5.9 > 5.12. I have tried both 12v and 24v PSU units (two versions of each), at the request of Mikrotik support. I have reset the unit to default, and only enabled my PPPoE internet connection. I have tried with uPNP on and off.

[admin@MikroTik] /interface wireless> print
Flags: X - disabled, R - running
0 R name="wlan1" mtu=1500 mac-address=00:0C:42:E2:1C:D0 arp=enabled
interface-type=Atheros 11N mode=ap-bridge ssid="home3" frequency=2412
band=2ghz-onlyn channel-width=20/40mhz-ht-above scan-list=default
wireless-protocol=any antenna-mode=ant-a wds-mode=disabled
wds-default-bridge=none wds-ignore-ssid=no bridge-mode=enabled
default-authentication=yes default-forwarding=yes default-ap-tx-limit=0
default-client-tx-limit=0 hide-ssid=no security-profile=home
compression=no

/interface wireless security-profiles> print
1 name="home" mode=dynamic-keys authentication-types=wpa2-psk
unicast-ciphers=aes-ccm group-ciphers=aes-ccm
wpa-pre-shared-key="interwebaccess" wpa2-pre-shared-key="interwebaccess"
supplicant-identity="" eap-methods="" tls-mode=no-certificates
tls-certificate=none static-algo-0=none static-key-0=""
static-algo-1=none static-key-1="" static-algo-2=none static-key-2=""
static-algo-3=none static-key-3="" static-transmit-key=key-0
static-sta-private-algo=none static-sta-private-key=""
radius-mac-authentication=no radius-mac-accounting=no

When I use the default security settings (i.e. open access), the CPU usage is greatly reduced:

/interface wireless security-profiles> print
Flags: * - default
0 * name="default" mode=none authentication-types="" unicast-ciphers=aes-ccm
group-ciphers=aes-ccm wpa-pre-shared-key="" wpa2-pre-shared-key=""
supplicant-identity="MikroTik" eap-methods=passthrough
tls-mode=no-certificates tls-certificate=none static-algo-0=none
static-key-0="" static-algo-1=none static-key-1="" static-algo-2=none
static-key-2="" static-algo-3=none static-key-3=""
static-transmit-key=key-0 static-sta-private-algo=none
static-sta-private-key="" radius-mac-authentication=no
radius-mac-accounting=no radius-eap-accounting=no interim-update=0s
radius-mac-format=XX:XX:XX:XX:XX:XX radius-mac-mode=as-username
radius-mac-caching=disabled group-key-update=5m
management-protection=disabled management-protection-key=""

Can someone help with the correct wireless settings to use? This is for a simple home setup, so various devices can work just by entering an access key. This is very frustrating, because even with security on, I cannot get the flash process to max out unless I use Skype - if I copy a 10gb file from wireless > wired connection, the CPU rises to ~70%, off which 30% is wireless. If I use the wireless machine to download 7 (legal) torrents via connections to 170 peers, the CPU rises to 30%. Stopping Skype use is not an option! Neither is having no security on the network.

The wireless cards in both laptops are the standard Apple Airport cards: Broadcom BCM43xx

There are so many wireless options, changing each individually to troubleshoot is not really an option. Currently, I'm having to use a separate access point in order to get a stable wireless connection which I can use Skype on....

Many thanks for any assistance.

+1

HTC Smartphone + Skype tops out CPU on 100% (ROS 5.12) Profiler shows: "flash"; writes are not increasing so I assume it reads something from flash, but what and why?

I suggest you redo the tests but this time use a Macbook connected to the wired interface and one connected wireless for Skype. When the issue appears try to connect from the wired one by ssh or telnet and issue "system sup-output" from console or try to connect by using MAC address with Winbox.
Be aware that if CPU is at 100% making supout should take a lot of time.

In such situation new ssh session or commands in already opened session usually just doesn't respond. Sometimes it takes minutes while command in opened session being executed. I'll try but not sure that it's possible.

I suggest you redo the tests but this time use a Macbook connected to the wired interface and one connected wireless for Skype. When the issue appears try to connect from the wired one by ssh or telnet and issue "system sup-output" from console or try to connect by using MAC address with Winbox.
Be aware that if CPU is at 100% making supout should take a lot of time.

As lostar mentions, that isn't really possible. Winbox/SSH/Web Access on the wired interface do not respond when the CPU is maxed out, in the case.

telnet or mac-telnet is the best choice in such situations. You should try that until you succeed, it's your best shot.
Otherwise what are your alternatives?

+1

HTC Smartphone + Skype tops out CPU on 100% (ROS 5.12) Profiler shows: "flash"; writes are not increasing so I assume it reads something from flash, but what and why?

we tried it but we couldn't make the router to start using the flash process. Could you email to support@mikrotik.com the support output file from your router?

No, because I was rebooted router and I can't reproduce issue today. (no configuration change)
The good point in this is that there is nothing major wrong with the ROS & Skype. There is probably a memory leak somewhere.
I will send support.rif as soon as I can reproduce this issue.

+1

HTC Smartphone + Skype tops out CPU on 100% (ROS 5.12) Profiler shows: "flash"; writes are not increasing so I assume it reads something from flash, but what and why?

we tried it but we couldn't make the router to start using the flash process. Could you email to support@mikrotik.com the support output file from your router?

I still have issues using a Macbook or Macbook Air and Skype. I have not been able to create a supout file.
This is a major barrier to me adopting Mikrotik across the business.

I had this once and since that I still can't reproduce this issue. I would recommend you to start with a factory default configuration and test with it. If it works you should go step-by-step in configuring your router and testing about every few steps.

Please check interface queues since bridge-local is defauled to only-hardware-queue while it not supports it. I have changed it to default.

I still have issues using a Macbook or Macbook Air and Skype. I have not been able to create a supout file.
This is a major barrier to me adopting Mikrotik across the business.

Please check interface queues since bridge-local is defauled to only-hardware-queue while it not supports it. I have changed it to default.

Thanks for the input; I will test that over the weekend if I get a chance. I have ordered non-mikrotik hardware for the production install and am currently using external access points which are stable.

A default config still has the issue. Can you explain the queue settings more - I don't seem to have a bridge queue?

[admin@MikroTik] /queue interface> print
Flags: D - dynamic
# INTERFACE QUEUE DEFAULT-QUEUE
0 ether1-gateway only-hardware-queue only-hardware-queue
1 ether2-master-local only-hardware-queue only-hardware-queue
2 ether3-slave-local only-hardware-queue only-hardware-queue
3 ether4-slave-local only-hardware-queue only-hardware-queue
4 ether5-slave-local only-hardware-queue only-hardware-queue
5 wlan1 only-hardware-queue wireless-default

[admin@MikroTik] /interface bridge> print
Flags: X - disabled, R - running
0 R name="bridge-local" mtu=1500 l2mtu=1598 arp=enabled
mac-address=00:0C:42:E2:1C:CC protocol-mode=rstp priority=0x8000
auto-mac=no admin-mac=00:0C:42:E2:1C:CC max-message-age=20s
forward-delay=15s transmit-hold-count=6 ageing-time=5m

From your /queue interface print
Try changing the only-hardware-queue to wireless-default.

I posted this on a different thread.

Apple does not always play nice with other "N" routers.

Just in case this information helps...

I do know that the Apple.com site has stated at one point that they have known compatibility issues with "N" routers. I have accessed all RouterBoard units I have deployed and changed the wireless setting from B/G/N to B/G only. NO one has noticed the difference and not one call for Wireless cutting out.

I posted this on a different thread.

Apple does not always play nice with other "N" routers.

Just in case this information helps...

I do know that the Apple.com site has stated at one point that they have known compatibility issues with "N" routers. I have accessed all RouterBoard units I have deployed and changed the wireless setting from B/G/N to B/G only. NO one has noticed the difference and not one call for Wireless cutting out.

Thanks for the advice. I've made that change, but still not fixed. Alongside an update to 5.17, in general it no longer restarts the router, but no new devices can join (wired or wireless), and no access to winbox or web admin. So essentially locked up until the Skype call finished, which is useless.

Back to an alternative router for me then