counters looks fine.> When I

noesberger · ‎06-14-2015

Hi

I have a problem in my home network and I'm not able to find the root-cause.

Sometimes during the day it happens, that I can't connect to the internet. The problem is that I can't ping the Cable Modem from my PC and the SG300 (acting as default-gw) has a very high latency on the ping and often also complete packet loss.

I have some sonos devices in the network, some of them are connected with cable and i found the following article: https://sonos.custhelp.com/app/answers/detail/a_id/2129/~/sonos-stp-cisco-switch-settings. I've modified the settings as described, but it's still the same problems.

Sometimes I'm still able to connect with ssh to the switch. What should I test to find the root-cause of the problem. I've checked "show spanning-tree" but no port is shown as blocked.

Thanks for any help or ideas.

Michal Bruncko · ‎06-15-2015

Hi

high latency for pinging your default gw could point to broadcast storm in your network. I am recommending you to connect to your switch via console and check system log. If ssh is working, you can use ssh then.

Do you have latest version of your switch firmware? Versions 1.4.x.x supports loopback detection and stp loopback detection. They are both disabled by default so I recommend you to enable them both.

But firstly focus on system log output and perhaps on show interface counters output to see ratio between unicast vs. multicast/bcast packets over each interface.

noesberger · ‎06-15-2015

Hi

Thanks for your reply.

The installed firmware is 1.4.1.3.

When I type "show logging" I can't see any special log entry. Is there an other command I can use to see more logging details?

Here the output of show interface counters:

Port InUcastPkts InMcastPkts InBcastPkts InOctets

---------------- ------------ ------------ ------------ ------------

gi1 63805 214 8008 7316836

gi2 0 0 0 0

gi3 9775099 2882 19190 3999817392

gi4 0 0 0 0

gi5 0 0 0 0

gi6 0 0 0 0

gi7 0 0 0 0

gi8 0 0 0 0

gi9 0 0 0 0

gi10 10 0 25862 2017636

gi11 375989 419510 15211 690009328

gi12 0 0 0 0

gi13 135 185 125 143844

gi14 13525 4256 899 5611210

gi15 37795 0 70491 10365199

gi16 0 0 0 0

gi17 30623 5551 1762 6244427

gi18 0 0 0 0

gi19 0 0 0 0

gi20 11037304 3185 563 12960641550

Port OutUcastPkts OutMcastPkts OutBcastPkts OutOctets

---------------- ------------ ------------ ------------ ------------

gi1 32692 492637 139697 549833649

gi2 0 0 0 0

gi3 11453674 489993 128532 13646568737

gi4 0 0 0 0

gi5 0 0 0 0

gi6 0 0 0 0

gi7 0 0 0 0

gi8 0 0 0 0

gi9 0 0 0 0

gi10 8465 492987 121868 546760532

gi11 476906 70455 131731 105463110

gi12 0 0 0 0

gi13 219 199 251 94458

gi14 18179 53950 48626 13239366

gi15 48651 510732 77248 574120960

gi16 0 0 0 0

gi17 48245 505206 146007 604505222

gi18 0 0 0 0

gi19 0 0 0 0

gi20 9335060 507583 147216 4487544046

Michal Bruncko · ‎06-16-2015

counters looks fine.

> When I type "show logging" I can't see any special log entry

what is logged during time when issue happen? anything?

you can also check switch uptime with "show system" command and confirm if switch is stable without accidental reboots during day.

one more question: during that issue you said that you observing high latency while you ping your modem. what about other devices connected to this switch? are you observing same latency during issue? if there is latency only toward your modem then probably your switch is OK and affected/utilized device is modem (attack from outside?).

SG300-28P