If I have Spanning Tree enabled and redundant links between switches will sho cdp nei det show all the connected links (even those that are not passing traffic because spanning tree has disabled them)?
Yes. Administrative and control plane traffic are still allowed over a "blocked" STP port. This is how trunks and etherchannels maintain their operational readiness when they are configured for dynamic negotiation. Otherwise, the failover time will be considerably longer during an outage.
A blocked port can't send any other packets that BPDUs
CDP packets are an exception to this rule?
In fact, a blocked port is allowed to send and receive any frames that will be processed by the switch without forwarding the further. Because such frames are never forwarded through a switch, they can not be caught in a switching loop. Think of protocols like CDP, LLDP, VTP, PAgP, LACP, UDLD, even STP. All these protocols can be both sent and received on a blocking port. It is in fact important that sending/receiving, for example, LACP frames is not prohibited on blocking port - otherwise, EtherChannels would cease working in this case.
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...