About the IPv6 Basic Packet Header
This topic identifies the IP version 6 (IPv6) basic packet header fields with their bit lengths and uses.
Specifies that IP version 6 is used. The IPv6 version field contains a value of 6 indicating that IPv6 is used, as opposed to 4 for IP version 4.
Allows source nodes or routers to identify different classes (or priorities for quality of service) for IPv6 packets. (This field replaces the IPv4 Type of Service field.)
Identifies the flow to which the packet belongs. Packets in a flow share a common purpose, or belong to a common category, as interpreted by external devices such as routers or destination hosts.
Note: For IPv6 flow-based packets, Junos OS for SRX Series devices does not use the flow label field.
Specifies the length of the IPv6 packet payload, or contents, expressed in octets.
Identifies the type of Internet Protocol for the header that immediately follows the IPv6 header. The Next Header field replaces the IPv4 Protocol field. It is an optional field.
This protocol can be one of two types:
The flow module processes these headers sequentially within the context of a packet flow.
If it encounters one of the following extension headers, the software parses it and regards the packet as a corresponding protocol packet.
Specifies the maximum number of hops the packet can make after transmission from the host device. When the Hop Limit value is zero, the device drops the packet and generates an error message. (This field is similar the to Time to Live IPv4 field.)
Source IP Address
Identifies the host device, or interface on a node, that generated the IPv6 packet.
Destination IP Address
Identifies the host device, or interface on a node, to which the IPv6 packet is to be sent.
Note: The destination address can appear twice, the first instance after the hop limit following the source IP address and the second instance after the final extension header.