MAC headers?

yaragalla_murali · 03-20-2010, 04:19 PM

Hi Who adds MAC headers to the TCP/IP packets. IS it hardware or software? If you look into TCP/IP packets the first part of the packet is MAC headers. so who adds this MAC headers to the packets? is it the network card or Software(could be OS or anything other than hardware)?

win32sux · 03-20-2010, 05:20 PM

It sounds like you're referring to Ethernet frames, not IP packets.

acid_kewpie · 03-20-2010, 05:36 PM

It's the sort of functionality that is conventionally performed by the hardware offload features on the NIC, but certainly possible to pull it back into pure software if more complex functionality is required.

tommylovell · 03-20-2010, 06:04 PM

Most "server class" NICs have a TCP/IP Offload feature; it is very unlikely that a "desktop class" commodity NIC (or a built-in laptop NIC) will have offload.

If your NIC has offload functionality it will add and remove the MAC headers; if no offload, or it is turned off, then the MAC header is added and removed in software.

yaragalla_murali · 03-21-2010, 12:43 AM

Quote:

win32sux It sounds like you're referring to Ethernet frames, not IP packets.

What is difference between frames and TCP/IP packets?

acid_kewpie · 03-21-2010, 04:00 AM

A whole layer in the OSI model. If you aren't aware of the differences, you should do some backgroud reading. Essentially though a TCP/IP packet is created with IP details etc, and payload, and then needs to be wrapped in whatever framing method is used for the link, e.g. ethernet, adsl, frame relay, isdn...

jschiwal · 03-21-2010, 07:19 AM

There is a book "Network Administrators Guide" (nag guide) on the www.tldp.org website I would highly recommend downloading and reading.

ericson007 · 03-22-2010, 01:28 PM

http://www.aboutdebian.com has all that info for free. It explain how packets are created, what info goes where and how routers differentiate between ip packets etc. quite a good read.