Is it possible to get symmetric hash from RSS for a given flow

Is it possible to get symmetric hash from RSS for a given flow

[Daniel Kan]

Hi,
It appears that the hash computed from RSS is unidirectional. Hence, for a 5-tuple flow, packet in one direction can be routed to a queue that may be different than packet in the other direction. I’m wondering if there is a configuration or mechanism to get a symmetric hash so that all packets for a given flow will be in the same queue. Thanks in advance. 

Dan

Re: Is it possible to get symmetric hash from RSS for a given flow

[Sangjin Han]

Hi,

This is exactly what you want:
http://www.ndsl.kaist.edu/~shinae/papers/TR-symRSS.pdf

Sangjin

On Thu, Feb 27, 2014 at 4:22 PM, Daniel Kan <dan-nm7580oGLDTQT0dZR+AlfA@public.gmane.org> wrote:
> Hi,
> It appears that the hash computed from RSS is unidirectional. Hence, for a 5-tuple flow, packet in one direction can be routed to a queue that may be different than packet in the other direction. I'm wondering if there is a configuration or mechanism to get a symmetric hash so that all packets for a given flow will be in the same queue. Thanks in advance.
>
> Dan

Re: Is it possible to get symmetric hash from RSS for a given flow

[Daniel Kan]

Thanks, Sangjin. This is exactly i’m looking for. Sorry, I should’ve googled it first. It’s good to know that hash key of repetitive 0x6d5a still yields good load balancing results.

Dan

On Feb 27, 2014, at 4:24 PM, Sangjin Han <sangjin-aFE07iDfcCIb0cFwG/AQJIdd74u8MsAO@public.gmane.org> wrote:

> Hi,
> 
> This is exactly what you want:
> http://www.ndsl.kaist.edu/~shinae/papers/TR-symRSS.pdf
> 
> Sangjin
> 
> On Thu, Feb 27, 2014 at 4:22 PM, Daniel Kan <dan-nm7580oGLDTQT0dZR+AlfA@public.gmane.org> wrote:
>> Hi,
>> It appears that the hash computed from RSS is unidirectional. Hence, for a 5-tuple flow, packet in one direction can be routed to a queue that may be different than packet in the other direction. I'm wondering if there is a configuration or mechanism to get a symmetric hash so that all packets for a given flow will be in the same queue. Thanks in advance.
>> 
>> Dan

Re: Is it possible to get symmetric hash from RSS for a given flow

[Stefan Baranoff]

Has anyone already applied this logic to IP only load balancing to get
SRC/DST and DST/SRC on the same queue and come up with an RSK value? If not
I'll spend some time with a calculator and see if I can get one.

Thanks,
Stefan

Sent from my smart phone; people don't make typos, Swype does!
On Feb 27, 2014 8:04 PM, "Daniel Kan" <dan-nm7580oGLDTQT0dZR+AlfA@public.gmane.org> wrote:

> Thanks, Sangjin. This is exactly i'm looking for. Sorry, I should've
> googled it first. It's good to know that hash key of repetitive 0x6d5a
> still yields good load balancing results.
>
> Dan
>
> On Feb 27, 2014, at 4:24 PM, Sangjin Han <sangjin-aFE07iDfcCIb0cFwG/AQJIdd74u8MsAO@public.gmane.org>
> wrote:
>
> > Hi,
> >
> > This is exactly what you want:
> > http://www.ndsl.kaist.edu/~shinae/papers/TR-symRSS.pdf
> >
> > Sangjin
> >
> > On Thu, Feb 27, 2014 at 4:22 PM, Daniel Kan <dan-nm7580oGLDTQT0dZR+AlfA@public.gmane.org> wrote:
> >> Hi,
> >> It appears that the hash computed from RSS is unidirectional. Hence,
> for a 5-tuple flow, packet in one direction can be routed to a queue that
> may be different than packet in the other direction. I'm wondering if there
> is a configuration or mechanism to get a symmetric hash so that all packets
> for a given flow will be in the same queue. Thanks in advance.
> >>
> >> Dan
>
>

Re: Is it possible to get symmetric hash from RSS for a given flow

[Daniel Kan]

The symmetric RSK for 5-tuple is a generalized case for 2-tuple src ip/dst ip. You can use the same RSK to get the symmetric load balancing. 

Dan

On Feb 27, 2014, at 5:08 PM, Stefan Baranoff <sbaranoff-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> Has anyone already applied this logic to IP only load balancing to get SRC/DST and DST/SRC on the same queue and come up with an RSK value? If not I'll spend some time with a calculator and see if I can get one.
> Thanks,
> Stefan
> 
> Sent from my smart phone; people don't make typos, Swype does!
> 
> On Feb 27, 2014 8:04 PM, "Daniel Kan" <dan-nm7580oGLDTQT0dZR+AlfA@public.gmane.org> wrote:
> Thanks, Sangjin. This is exactly i’m looking for. Sorry, I should’ve googled it first. It’s good to know that hash key of repetitive 0x6d5a still yields good load balancing results.
> 
> Dan
> 
> On Feb 27, 2014, at 4:24 PM, Sangjin Han <sangjin-aFE07iDfcCIb0cFwG/AQJIdd74u8MsAO@public.gmane.org> wrote:
> 
> > Hi,
> >
> > This is exactly what you want:
> > http://www.ndsl.kaist.edu/~shinae/papers/TR-symRSS.pdf
> >
> > Sangjin
> >
> > On Thu, Feb 27, 2014 at 4:22 PM, Daniel Kan <dan-nm7580oGLDTQT0dZR+AlfA@public.gmane.org> wrote:
> >> Hi,
> >> It appears that the hash computed from RSS is unidirectional. Hence, for a 5-tuple flow, packet in one direction can be routed to a queue that may be different than packet in the other direction. I'm wondering if there is a configuration or mechanism to get a symmetric hash so that all packets for a given flow will be in the same queue. Thanks in advance.
> >>
> >> Dan
>