[Click] Click packet size

[Eddie Kohler]

Hi Roman,

At least some of the extra bytes are for, e.g., VLANs (although I can't 
remember at the moment whether VLANs actually change the mtu).  We also 
add some slack to reduce "expensive pushes" and "expensive puts", where 
there isn't enough room in a packet for an additional header (in case 
the packet is being fragmented, or sent out on another link technology). 
  But mostly I think it's just historical accident.

Eddie


Roman Chertov wrote:
> Hello,	
> 	I am curious as to why Click allocates 1536+16 byte skbs when it 
> receives packets in PollDevice?  1500byte MTU and 18 bytes for an 
> Ethernet header/footer.  Are the extra bytes there just in case? (e.g. 
> eepro100).
> 
> Roman
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