We have 2 sites interconnected with WAN links. The WAN connectivity is based on Serial P2P links. However the problem that we are facing is that when we configure the HDLC protocol at both ends, the line protocol remains down even though both side routers are Cisco(Cisco 2600 series). We are able to bring the Line Protocol up with the PPP.
Please can someone advise as to what could be the possible reason for the same and suggest some points that we can check.
Many thanks in advance.