Link and network level in the tcp/ip stack

Brian Seklecki bseklecki at
Sun May 8 01:49:29 UTC 2011

On 5/7/2011 6:41 PM, Erik Nørgaard wrote:
> So the question is which behaviour is correct, recommended or accepted?
> Stripping the link layer and reply according to the network layer, or
> keeping the link layer?

This is the way it in every TCP/IP stack out there.

The routing decision for the reply IP packet of the ICMP message is made 
independently of the upper-OSI-layer TCP state.

In this instance, its a bit inconvenient for you, but having these 
layers abstracted makes for incredible flexibility in TCP/IP; the same 
thinking as small POSIX utilities work independently is more flexible.

Brian A. Seklecki <bseklecki at>
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