Subject: Re: [PATCH net-next v2] ethtool: ice: Support for RSS settings to GTP from ethtool

From: Harald Welte <[email-masked]>
Date: Wed, 18 Oct 2023 19:57:14 +0200

Hi Jakub,

On Wed, Oct 18, 2023 at 10:37:03AM -0700, Jakub Kicinski wrote:
> Harald went further and questioned use of the same IP addresses for 
> -U and -C traffic, but even within one endpoint aren't these running
> on a different port? 

yes.

> Can someone reasonably use the same UDP port for both types of traffic?

I don't think so.  In the entire 3GPP protocol world, the UDP port numbers
for GTP-U and GTP-C are fixed.  The various signaling protocols allow you to
communicate the IPv4/v6 address and TEID of tunnel endpoints, but never allow
you to communicate the port number - which hence must always be the well-known port
(2123 for GTP-C + 2152 for GTP-U).

Of course somebody could do whatever they want in some kind of internal interface
not required to interoperate with any other equipment/implementation/operator, but
I'd consider it not falling in your question of "reasonable use".

Regards,
	Harald

-- 
- Harald Welte <[email-masked]>          https://laforge.gnumonks.org/
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