CODEWITHSUNDEEP
network-programmingtcpip
Mike G
Mike G

Reputation: 4959

IPv6 Header Priority

From this site (http://www.ipv6.com/articles/general/IPv6-Header.htm) , it says:

Packet priority/Traffic class (8 bits) The 8-bit Priority field in the IPv6 header can assume different values to enable the source node to differentiate between the packets generated by it by associating different delivery priorities to them. This field is subsequently used by the originating node and the routers to identify the data packets that belong to the same traffic class and distinguish between packets with different priorities.

I was wondering, if it is possible to actually "hack" the TCP/IP stack in order to give your packets higher priority. Would you get any substantial gain in network performance. Also, if it is possible, how is it prevented?

Upvotes: 1

Views: 1267

Answers (3)

amanpreet singh
amanpreet singh

Reputation: 44

The source can change the priority but the routers and gateway will can change the priority depending upon the type of packet that is

Upvotes: 0

neirbowj
neirbowj

Reputation: 645

Yes, it's possible, but it's not really hacking. There is a standard programming interface that will allow your program to indicate to the stack how it would like the Traffic Class header field to be populated.

Whether or not you will measure any performance difference depends on the network that handles your packets. Think of the Traffic Class field as a hint for the network; a suggestion for how you would like your packet to be handled. The network might ignore it, or even change it to a different code point. Furthermore, the notion of "priority" (also known as "precedence") as an interpretation of the Traffic Class field has receded into a much richer collection of Per Hop Behaviors (PHBs).

See IETF RFC 3542 Advanced Sockets Application Program Interface (API) for IPv6. In particular, read the first part of Section 4, Access to IPv6 and Extension Headers, and Section 6.5, Specifying/Receiving the Traffic Class value.

Here is a code snippet that sets the Traffic Class field to the integer MY_TCLASS for all packets sent on the socket sk.

int tclass;
tclass = MY_TCLASS;
setsockopt(sk, IPPROTO_IPV6, IPV6_TCLASS, &tclass, sizeof(int));

Related reading:

Upvotes: 1

user207421
user207421

Reputation: 310909

I don't understand the question. You don't need to hack anything. There's an API provided for setting the TC on a socket. What effect it has depends on the cooperation of the intervening routers.

Upvotes: 0

Related Questions