-
Find all the Fragments and Field Values for Fragment Headers in Slide 20 of our notes.
Original Datagram (=Packet) = 404 Octets/Bytes
Offset = 0
More = 0
Fragment (Data+IP Header=Payload) Limit = 208 Bytes
With a minimum 20 bytes Header Size
- *IMPORTANT: Offset calculation is done on the Data Payload ONLY!!!
- --> Offset = Payload / 8
Original datagram payload = Data(384bytes) + Header(20bytes)
1st Fragment: - Length = 208 Bytes
- Offset = 0
- More = 1
- 2nd Fragment:
- Length = 208 Bytes
- Offset = (208-20)/8 = 23.5 bytes
- More = 1
- 3rd Fragment:
- Payload = (384 - (188+188)) = 8bytes left
- = 8 + 20 = 28bytes
- Length = 28 bytes
- Offset = 8(payload) / 8 = 1
- More = 0
-
An IP Datagram of length 4326 Bytes needs to be sent on a LAN (Local Area Network) that uses CSMA/CD Protocol. How many fragments will need to be sent for this original IP Datagram? Mention all needed fields for all resulting fragments
- Original Datagram (=Packet) = 4326 Bytes
- Max Payload of Ethernet = 1500 Bytes
- Max IP packet size = 1500 = Data(1500-20 = 1480 bytes) +Header(20 bytes)
- 1st Fragment:
- Length = (1480+20) = 1500 bytes
- Offset = 0
- More = 1
- 2nd Fragment:
- Length = 1500 bytes
- Offset = (1500 - 20)/8 = 185 bytes
- More = 1
- 3rd Fragment:
- Length = 4306(original) - 1480 - 1480 = 1346bytes
- = 1346 + 20 = 1366 bytes
- Offset = 4326(original)-1346(length)=2980
- = (2980 - 20) / 8 = 370 bytes
- More = 0
-
Find the Number of Networks and Number of Hosts that can be supported by a Class A, Class B and Class C (used for unicast) IP Address Type.
- Clss | Lft Bits | NetID | HostID | #Networks | #Hosts
- A 0xxx 8 24 ~27 (-2) ~224 (-2)
- B 10xx 16 16 ~214 (-2) ~216 (-2)
- C 110x 24 8 ~221 (-2) ~28 (-2)
-
Read RFC-791, RFC-1071 and RFC-790. What are they, what is their significance?
- RFC-791 refers to the Internet Protocol (IP): Forwarding and Addressing in the Internet, focusing on IPv4. It revises aspects of addressing, error handling, option codes, and the security,
- precedence, compartments, and handling restrictions features of the Internet
- Protocol.
- RFC-1071 refers to the computing
- of Internet Checksum that is used by the standard Internet protocols IP, UDP,
- and TCP. It informs about the techniques and algorithms for efficiently
- computing the Internet Checksum, considering that the efficiency of checksum
- implementation is critical to a good performance.
- RFC-790 refers to the Assigned
- Network Numbers/Assigned Numbers. This Network Working Group Request for
- Comments documents the currently assigned values from several series of numbers
- used in network protocol implementations.
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