3Com MSR 50 Series Configuration Manual page 1698

1698 C 90: DAR C
HAPTER ONFIGURATION
Figure 476 Fields of the IP datagram
The protocol field in the header is 8-bit long. This field is called protocol domain.
The values of protocol domain indicate the protocol type of IP packets.
See the following table for values of protocol domain in the IP datagram.
Corresponding protocols of protocol domain values in the IP datagram
Protocol domain value
1
2
4
6
8
17
47
50
51
88
IP fragmentation format
See Figure 477 for the "3-bit Flag" structure of IP datagram.
Figure 477 3-bit Flag
In which, the later 2 bits control the fragment of IP packets. The 3 bits are defined
as follows:
Reserved: it is required to be 0;
■
Do not fragment bit: 0 indicates fragmentation is allowed, and 1 indicates no
■
to fragment;
Protocol type
ICMP
IGMP
IPINIP
TCP
EGP
UDP
GRE
ESP
AH
EIGRP