So I was trying to set up some fancy (legacy technology at this point) Frame Relay stuff for labbing OSPF. I encountered:
R1(config)#int s1/2.1 multipoint % Warning: cannot change link type
Hmm weird I thought. Before blaming this on GNS3 or a crappy image, I did some shallow digging on Google. Apparently, a lot of newbies like me have run into this problem. The solution is that Cisco subinterfaces default to being in point-to-point mode. Once created, it cannot be changed to a multipoint interface without doing the following:
R1(config)#no int s1/2.1 Not all config may be removed and may reappear after reactivating the sub-interface R1(config)#int s1/2.1 multipoint R1(config-subif)#
Hey I’m in! Just a quick FYI for those who may be miffed by the idiosyncrasies of Cisco IOS. This was on 12.4T.