09/02/2024 13:11, Ferruh Yigit:
On 2/9/2024 10:12 AM, Thomas Monjalon wrote:
09/02/2024 00:54, Ferruh Yigit:
On 1/30/2024 11:25 AM, Gavin Li wrote:
Currently, DPDK supports VXLAN and VXLAN-GPE with similar header
structures and we are working on adding support for VXLAN-GBP which is
another extension to VXLAN. More extension of VXLAN may be added in the
future.
VXLAN and VXLAN-GBP use the same UDP port(4789) while VXLAN-GPE uses a
different one, 4790. The three protocols have the same header length and
overall similar header structure as below.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|R|R|R|I|R|R|R| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VXLAN Network Identifier (VNI) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: VXLAN Header
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|R|Ver|I|P|B|O| Reserved |Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VXLAN Network Identifier (VNI) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: VXLAN-GPE Header
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|G|R|R|R|I|R|R|R|R|D|R|R|A|R|R|R| Group Policy ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VXLAN Network Identifier (VNI) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: VXLAN-GBP Extension
Both VXLAN-GPE and VXLAN-GBP extended VXLAN by redefining its reserved
bits, which means the packets can be processed with same pattern and most
of the code can be reused. Instead of adding more new items by
copying/pasting code for the VXLAN extensions in the future, it’s better
to use existing VXLAN infrastructure and add support code in it.
Hi Gavin,
The motivation is to prevent code duplication, and the code mentioned is
the driver code, right?
The motivation is mainly to provide a unified and more explicit API.
From user perspective, I think existing approach is more explicit,
because it sets VXLAN or VXLAN_GPE flow types.
I am trying to understand the benefit, how unifying flow type in the API
helps to the user?
Overall OK to unify "struct rte_vxlan_hdr" although it makes the struct
a little complex, perhaps we can consider extraction some nested structs
as named struct, no strong opinion.
But not sure about removing the flow item types for VXLAN-GPE, or not
adding for VXLAN-GBP.
Think about a case user adding a rule, which has a item type as VXLAN
and in the protocol header some bits are set, lets say first word, last
byte is set, how driver will know if to take it as GPE "next protocol"
or "group policy id".
The driver may decide depending on the UDP port and some distinguishing flags.
If you want to match on GBP, you should includes the GBP flag in your pattern,
no need to use a separate item.
Why not be more explicit?
It helps to driver to know more about the pattern to be able to create
proper flow rule, if there is an obvious way for driver to differentiate
these protocol extensions, and flow item type is redundant, I can
understand the proposal, but otherwise I think better to keep flow items
for extensions.
In any case we need the simple VXLAN item.
If we have GPE and GBP specialized items,
what means a match on the simple VXLAN?
Does it include packets with other extensions or exclude them?
Matching the bits in the protocol make such decision explicit.
When a rule is set in HW, HW may not care about the protocol, as long as
bits in the rule match with the packet, HW can apply the action.
But for driver to be able to set the rule properly, it needs more
explicit information.
Yes information is in the pattern to match.
Lets assume driver API get a pattern with 'RTE_FLOW_ITEM_TYPE_VXLAN'
type and "struct rte_flow_item_vxlan", at this point driver doesn't know
if it is VXLAN or any of the extensions.
Yes it knows because of the matched bits in the pattern.
If the rule specify a match on GBP flag = 1, it is GBP only.
If the rule specify a match on GBP flag = 0, it excludes GBP.
If the rule does not mask GBP flag, it includes GBP.
