configured two Catalyst 2960G switches connected via trunk ports. Configured on both of them int vlan1 with IP address from the same subnet 192.168.52.0/24. Configured all other ports on both switches with
sw mo acc
sw acc vlan 1
When I physically ethernet-connect to switch #1 I can ping and telnet it but not #2. And vice versa when I plug the laptop cable to switch #2 i can perfectly well ping and telnet it but NOT #1. From the IOS console I can sh cdp neighbors, it shows me the other devices properties and port number but even from there the ping does not succeed.
to make long story short: it was not a switching problem. E.g. both trunk ports had the vlan 1 as native, both interfaces were up, etc...
What really caused the problem was a remnant from the past, where all the ports of one of the switches were "restricted" to single client with
The latter was confidgured for the trunk port as well, leading to the default setting of maximum 1. If it wasn't for the Cisco Network Assistant that I fired up and saw over 1000 blocked connections it would have been even longer to define this single line of misconfiguration.
Still thanks a million for the help offered at hard times!