The document discusses the header fields of an IP packet, including: - Version, Header Length, Type of Service, Total Length, Identification, Flags, Fragmentation Offset, Time to Live, Protocol, Header Checksum, Source Address, and Destination Address. It provides details on the number of bits used for each field and what information is specified. For example, it states that Version is 4 bits and indicates the IP version used, that Total Length is 16 bits and gives the packet length in bytes, and that Flags is 3 bits and controls fragmentation. The document also gives examples of IP datagrams and asks to identify the values for each header field, like Version, Header Length, Source Address, etc

1. Pertemuan 3
Marti Widya Sari, S.T., M.Eng

2. 30 September 2013IP Packet 2
Version HLen TOS Length
Identification Flags Offset
TTL Protocol Checksum
Source Address
Destination Address
Options (variable) Pad
(variable)
0 4 8 16 19 31
Data

3.  Version : 4 bit
 HLEN (header length) : 4 bit
 TOS : 8 bit
 Length : 16 bit
 Identification : 16 bit
 Flags : 3 bit
 Fragmentation offset : 13 bit
 TTL : 8 bit
 Protocol : 8 bit
 Header checksum : 16 bit
 Source address : 32 bit
 Destination address : 32 bit
30 September 2013IP Packet 3

4.  Version—Versi IP yang digunakan (0100=4)
 IP Header Length (IHL)—Datagram header length
dalam 32-bit words.
 Type-of-Service—Specifies how an upper-layer
protocol would like a current datagram to be
handled, and assigns datagrams various levels of
importance.
 Total Length—Panjang paket dalam bytes,
termasuk data dan header.
 Identification—Nilai integer ebagai identifikasi
paket saat ini. Item ini berguna pada fragmentation
jika paket terdiri atas potongan-potongan paket
besar
30 September 2013IP Packet 4

5.  Flags—Consists of a 3-bit field of which the two
low-order (least-significant) bits control
fragmentation.
◦ The low-order bit specifies whether the packet can be
fragmented.
◦ The middle bit specifies whether the packet is the last
fragment in a series of fragmented packets.
◦ The third or high-order bit is not used.
 Fragment Offset—Indicates the position of the
fragment's data relative to the beginning of the
data in the original datagram, which allows the
destination IP process to properly reconstruct the
original datagram.
30 September 2013IP Packet 5

6.  Time-to-Live—Maintains a counter that gradually
decrements down to zero, at which point the
datagram is discarded. This keeps packets from
looping endlessly.
 Protocol—Indicates which upper-layer protocol
receives incoming packets after IP processing is
complete.
 Header Checksum—Helps ensure IP header
integrity.
 Source Address—Specifies the sending node.
 Destination Address—Specifies the receiving node.
 Options—Allows IP to support various options,
such as security.
 Data—Contains upper-layer information.
30 September 2013IP Packet 6

7.  Diketahui sebuah ip datagram source sebagai berikut :
 45 00 00 54 00 03 00 00 20 06 00 00 7C 4E 03 02 B4 0E
0F 02
 Carilah masing-masing :
a. Version
b. HLEN
c. TOS
d. Length
e. Identification
f. flags
g. Fragmentation offset
h. TTL
i. Protocol
j. Header Checksum
k. Source Address
l. Destination Address
30 September 2013IP Packet 7

8.  Diketahui sebuah ip datagram source sebagai berikut :
 45 00 00 54 00 03 00 00 20 17 00 00 5E 4F 03 02 C4 6E
B4 52
 Carilah masing-masing :
a. Version
b. HLEN
c. TOS
d. Length
e. Identification
f. flags
g. Fragmentation offset
h. TTL
i. Protocol
j. Header Checksum
k. Source Address
l. Destination Address
30 September 2013IP Packet 8