I wonder in my study I found configured 2 router point2point with different ip segment that with HDLC both router can not ping each other, but with PPP their are can.
R1#sho run int s1/0 Building configuration... Current configuration : 98 bytes ! interface Serial1/0 ip address 192.168.1.1 255.255.255.0 no fair-queue clockrate 128000 endR2#sho run int s1/1 Building configuration... Current configuration : 65 bytes ! interface Serial1/1 ip address 192.168.4.2 255.255.255.0 endHDLC as point2point protocols
R1#sho int s1/0 Serial1/0 is up, line protocol is up Hardware is M4T Internet address is 192.168.1.1/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation HDLC, crc 16, loopback not set ---------cut ----------------------both p2p config I used default so it’s use HDLC
R2
R2#sho ip int brief Serial1/1 192.168.4.2 YES manual up upR1
R1#sho ip int brief Serial1/0 192.168.1.1 YES manual up up R1#sho int s1/0 Serial1/0 is up, line protocol is up Hardware is M4T Internet address is 192.168.1.1/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation PPP, ------------ cut unused line------------Lets ping:
R1#ping 192.168.4.2 Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 192.168.4.2, timeout is 2 seconds: ..... Success rate is 0 percent (0/5)ping are failed from R1 to R2
then lets compare with PPP
R1#sho run int s1/0 Building configuration... Current configuration : 142 bytes ! interface Serial1/0 ip address 192.168.1.1 255.255.255.0 encapsulation ppp no fair-queue clockrate 128000 ppp authentication chap endPPP configure in both router for match L2 P2p Protocols
R1#ping 192.168.4.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.4.2, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 24/76/96 ms R1#notes:
“PPP advertise out the interface ip address to the other Router using /32 prefix. so Router will think OK it’s same subnet with me, then let reply the echo”
“A route with a /32 prefix, representaing a single host, is calles a host route”