For this case, assume that the requesting host is on class C network 192.1.127.0, has address 192.1.127.19, that there is a gateway at 192.1.127.50, and that on network an 3-bit subnet field is in use (01011000), that is, the address mask is 255.255.255.88.
The host sends the ICMP request to 255.255.255.255:
Source address: 192.1.127.19 Destination address: 255.255.255.255 Protocol: ICMP = 1 Type: Address Mask Request = AM1 Code: 0 Mask: 0The gateway can then respond directly to the requesting host.
Source address: 192.1.127.50 Destination address: 192.1.127.19 Protocol: ICMP = 1 Type: Address Mask Reply = AM2 Code: 0 Mask: 255.255.255.88.In the diskless workstation case the host sends:
Source address: 0.0.0.0 Destination address: 255.255.255.255 Protocol: ICMP = 1 Type: Address Mask Request = AM1 Code: 0 Mask: 0192.1.127.50 will hear the datagram, and should respond with this datagram:
Source address: 192.1.127.50 Destination address: 255.255.255.255 Protocol: ICMP = 1 Type: Address Mask Reply = AM2 Code: 0 Mask: 255.255.255.88.If broadcasting is not allowed 192.1.127.19 sends:
Source address: 192.1.127.19 Destination address: 192.1.127.50 Protocol: ICMP = 1 Type: Address Mask Request = AM1 Code: 0 Mask: 0192.1.127.50 should respond exactly as in the previous case.
Source address: 192.1.127.50 Destination address: 192.1.127.19 Protocol: ICMP = 1 Type: Address Mask Reply = AM2 Code: 0 Mask: 255.255.255.88