Cisco Cisco Firepower Management Center 4000

Protection

The following listing describes protocol-specific information that might appear in an IPv4 packet.

The Internet Protocol version number.

The number of bytes in the header, including any IP options. An IP header with no options is 20 
bytes long.

The values for differentiated services that indicate how the sending host supports Explicit 
Congestion Notification (ECN):

0x0

 — does not support ECN-Capable Transport (ECT)

0x1

 and 

0x2

 — supports ECT

0x3

 — Congestion Experienced (CE)

The length of the IP packet, in bytes, minus the IP header.

The value that uniquely identifies an IP datagram sent by the source host. This value is used to trace 
fragments of the same datagram.

The values that control IP fragmentation, where:

values for the Last Fragment flag indicate whether there are more fragments associated with the 
datagram:

0

 — there are no more fragments associated with the datagram

1

 — there are more fragments associated with the datagram

values for the Don’t Fragment flag control whether the datagram can be fragmented:

0

 — the datagram can be fragmented

1

 — the datagram must not be fragmented

The value for the fragment offset from the beginning of the datagram.

The remaining number of hops that the datagram can make between routers before the datagram 
expires.

The transport protocol that is encapsulated in the IP datagram; for example, ICMP, IGMP, TCP, or 
UDP.