We have problem with the ring of 802.1q trunk links. All the links are 1Gbps, and only one of them is 100Mbps. 100Mbps link connects root switch (3750) port with non-root (CE-500) one. Surprisingly, SPT blocks 1Gbps ports on that non-root switch. Link cost of 100Mbps is properly set to 19, while one for 1Gbps is set to 4. What's the reason?
Well so SW1-4 are using their paths to root through SW1 but only SW5 is taking the direct path.
If the above understanding is correct, then STP is behaving normally
Selection of root path depends on the port cost. Gig port cost is 4 and FE cost is 19. For SW5, the cost through sw4-3-2-1-root becomes 20 but the cost of the path directly to root is 19. So the switch is choosing the direct path even though it is having less bandwidth.
Yes you can alter port cost on a perticular switch for a perticular VLAN or for all the traffic. Of course, if you HAVE to do this, please do it very carefully and after considering other techincal details of your network. Please check thefollowing link for this
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...