They cannot communicate.
HDLC
HDLC
HDLC
encapsulation hdlc
Data link layer protocols like PPP and HDLC define how data is encapsulated for transmission across a WAN link.
HDLC
HDLC
HDLC
1. Frame Relay 2. HDLC 3. PPP
there may be the issue with the layer 2 protocol like hdlc or ppp is not configured or wrongly configured if the interface is serial interface.
Serial interfaces do not pass any MAC information because the information is formed using WAN encapsulation (PPP. HDLC, Frame Relay).
multiprotocol support