Cotse - Connected: An Internet Encyclopedia - 3. A Class C Network Case (illustrating non-contiguous subnet bits)

3. A Class C Network Case (illustrating non-contiguous subnet bits) Connected: An Internet Encyclopedia
3. A Class C Network Case (illustrating non-contiguous subnet bits)

Up: Connected: An Internet Encyclopedia
Up: Requests For Comments
Up: RFC 950
Up: Appendix II. Examples
Prev: 2. A Class B Network Case
Next: Appendix III. Glossary

3. A Class C Network Case (illustrating non-contiguous subnet bits)

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:                    0

The 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:                    0

192.1.127.50 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:                    0

192.1.127.50 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

Next: Appendix III. Glossary

Connected: An Internet Encyclopedia
3. A Class C Network Case (illustrating non-contiguous subnet bits)


		Cotse.Net

Protect yourself from cyberstalkers, identity thieves, and those who would snoop on you.
Stop spam from invading your inbox without losing the mail you want. We give you more control over your e-mail than any other service.
Block popups, ads, and malicious scripts while you surf the net through our anonymous proxies.
Participate in Usenet, host your web files, easily send anonymous messages, and more, much more.
All private, all encrypted, all secure, all in an easy to use service, and all for only $5.95 a month!

Service Details