[pcap-ng-format] EPB hash algorithms

[Stephen Hemminger]

On Wed, 25 Sep 2019 19:08:59 +0200
Jasper Bongertz <jasper at packet-foo.com> wrote:

> Wednesday, September 25, 2019, 7:03:15 PM, Stephen Hemminger wrote:
> 
> > The Enhanced Packet Block format has option for hash.
> > The epb_hash does not support the most common hash algorithm
> > supported by most NIC's. The Toeplitz hash function is used by
> > both Linux and Windows, and is required as part of the NDIS spec
> > so hardware vendors all do it.  
> 
> > But the documentation for ebp_hash says:
> > The hashing algorithm can be: 
> > 2s complement (algorithm octet = 0, size=XXX), 
> > XOR (algorithm octet = 1, size=XXX), 
> > CRC32 (algorithm octet = 2, size = 4), 
> > MD-5 (algorithm octet = 3, size=XXX), 
> > SHA-1 (algorithm octet = 4, size=XXX).  
> 
> > Why not Toeplitz?  
> 
> I think the simple answer is that nobody thought of it, or even knew about it -
> I have to admit I never heard the name of this hash function before this email.
> I guess this can be easily fixed by adding algorithm octet = 5 for Toeplitz.
> 

Toeplitz hash is widely used for Receive Side Scaling.
https://en.wikipedia.org/wiki/Toeplitz_Hash_Algorithm