DDP and symmetric RSS hash

[Stephen Hemminger]

On Mon, 29 Jan 2024 19:18:38 +0300
Виктория Доможакова <v.domozhakova at yandex.ru> wrote:

> Hi,
> I'm trying to set toeplitz symmetric hash function for packets from DDP.
> I've created flows for pppoe/pppol2tpv2/l2tpv2 headers in patterns and PCtypes as RSS hash types. But it is not working.
> What should I do to configure toeplitz symmetric hash function for packets from ddp?
>  
> Best regards,
> Viktoriya Domozhakova
> 

With most hardware you have to use a Toeplitz key which results in the symmetric hash.
Some hardware does symmetric hash by setting

	/**
	 * Symmetric Toeplitz: src, dst will be replaced by
	 * xor(src, dst). For the case with src/dst only,
	 * src or dst address will xor with zero pair.
	 */
	RTE_ETH_HASH_FUNCTION_SYMMETRIC_TOEPLITZ,
	/**
	 * Symmetric Toeplitz: L3 and L4 fields are sorted prior to
	 * the hash function.
	 *  If src_ip > dst_ip, swap src_ip and dst_ip.
	 *  If src_port > dst_port, swap src_port and dst_port.
	 */
	RTE_ETH_HASH_FUNCTION_SYMMETRIC_TOEPLITZ_SORT,

But that is restricted to newer smart NICs.