I assume you use 10.100.1.254 mask 255.255.0.0 for your FE. So the total available subnet you can use is 10.100.0.1 - 10.100.255.254. This is a huge subnet, I would suggest you lower down it to 255.255.255.0 if you do not require that big subnet.
As for the Serial, I assume you are using 10.101.1.254/255.255.255.0
FYI, most point-to-point link just require not more than 2 host, so please use 10.101.1.254/255.255.255.252. (other available IP is 10.101.1.253). It just my opinion.. you can still use 255.255.255.0 if you want. :-)
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...