Hi Harald,
On 12/12/2020 11:07, Harald Welte wrote:
Hi Jonas,
On Fri, Dec 11, 2020 at 01:26:07PM +0100, Jonas Bonn wrote:
From 3GPP TS 29.281:
"...the UDP Source Port or the Flow Label field... should be set dynamically
by the sending GTP-U entity to help balancing the load in the transport
network."
You unfortuantely didn't specifiy which 3GPP release you are referring to.
Sorry about that. I'm looking at v16.1.0.
At least in V15.7.0 (2020-01) Release 15 I can only find:
"For the messages described below, the UDP Source Port (except as
specified for the Echo Response message) may be allocated either
statically or dynamically by the sending GTP-U entity. NOTE: Dynamic
allocation of the UDP source port can help balancing the load in the
network, depending on network deployments and network node
implementations."
For GTPv0, TS 29.060 states:
"The UDP Source Port is a locally allocated port number at the sending
GSN/RNC."
unfortuantely it doesn't say if it's a locally allocated number globally
for that entire GSN/RNC, or it's dynamic per flow or per packet.
I could interpret that to mean that the receiving end shouldn't be too
bothered about what port a packet happens to come from... That said,
dynamic per flow is almost certainly what we want here as this is mostly
about being able to trigger receive side scaling for network cards that
can't look at inner headers.
As I'm aware of a lot of very tight packet filtering between GSNs,
I would probably not go for fully dynamic source port allocation
without some kind of way how the user (GTP-control instance) being
able to decide on that policy.
Sure... sounds reasonable. A flag on the link setup indicating dynamic
source port yes/no should be sufficient, right?
/Jonas
