Again its not always so simple. The ISDN bearer channel is rightly regarded as a switched layer2 technology. But considering that the ISDN network allows a client to open a connection to any point on a meshed network it could be considered to show layer3 characteristics.
Also LAPD which runs on the D channel is considered to be layer 2 (a modification of LAPB). So what is Q.931 which runs over it? This is a layer 3 protocol in a very real sense. The D-channel also supports X.25 packet data over LAPD so again this could be considered to be both Layer 2 and 3.
But if you look at it from the conventional perspective of IP, then these are all just part of a layer 2 process and are therefore all Data Link layer.
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...