can this be a unicast flooding problem? pls tell me if you need further info. -----Original Message----- From: Jason R. Martin [mailto:nsxfreddy@xxxxxxxxx] Sent: Wednesday, July 27, 2005 11:01 PM To: sameer.neugui@xxxxxxxxxxxxxxxx; Linux 802.1Q VLAN Subject: Re: [VLAN] STP+VLAN On 7/27/05, sameer <sameer.neugui@xxxxxxxxxxxxxxxx> wrote: > Hi all, > > I am basically facing a problem with STP. But since STP is related to VLAN > in some respect I guess there would be someone here who can help me. > > Background: > > We have developed a layer two switch. This uses Cirrus logic's ep9301 > processor, embedded Linux 2.4.21 kernel as the OS and zarlink's switch > controller. > > The observation: > > 1)we have 2 switches, switch A and switch B > > 2)port 1 and port 2 of switch A are connected to port 1 and port 2 of switch > B > > 3)1 PC is connected to port 0 of switch A and another to COM port of switch > A to observe STP > > 4)We restart the 2 switches and observe that one of the links is blocked and > the other in forwarding state. STP is always enabled on reboot > > 6)We start to ping switch A and the switches and the two PC hang. > > 7)the LEDs on the switch device that signify the activity are seen > continuously glowing. > > 8)switch A and B, PC 1 and 2 cannot be accessed at all. > > 9) We remove one of the links and the STP reconfigures and the switch A can > be pinged. > > 10)Most of the time we have observed, although not a confirmed pattern, that > if we remove the blocked link, the STP just disables the port on switch A > (we have not observed the counter part on the switch B > > 11)Neither the switches nor the PCs were on the rest of the company network > > Its not a hang exactly as upon some topology change the system is back to > working. I also checked on the internet. On cisco site I found something > called unicast flooding. Is this the reason for the system to blog down? > what would be the fix or some pointer in this regard? Sounds to me like the link that is "blocked" isn't really blocked and you're getting a loop. Jason
