Re: [virtio-dev] [PATCH v17] virtio-net: support inner header hash

[Heng Qi <hengqi@linux.alibaba.com>]

Hi all!

If after reviewing it you feel this version meets the necessaryrequirements,
I kindly request a vote.

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/173

Thanks a lot!




在 2023/6/12 下午4:09, Heng Qi 写道:
> 1. Currently, a received encapsulated packet has an outer and an inner header, but
> the virtio device is unable to calculate the hash for the inner header. The same
> flow can traverse through different tunnels, resulting in the encapsulated
> packets being spread across multiple receive queues (refer to the figure below).
> However, in certain scenarios, we may need to direct these encapsulated packets of
> the same flow to a single receive queue. This facilitates the processing
> of the flow by the same CPU to improve performance (warm caches, less locking, etc.).
>
>                 client1                    client2
>                    |        +-------+         |
>                    +------->|tunnels|<--------+
>                             +-------+
>                                |  |
>                                v  v
>                        +-----------------+
>                        | monitoring host |
>                        +-----------------+
>
> To achieve this, the device can calculate a symmetric hash based on the inner headers
> of the same flow.
>
> 2. For legacy systems, they may lack entropy fields which modern protocols have in
> the outer header, resulting in multiple flows with the same outer header but
> different inner headers being directed to the same receive queue. This results in
> poor receive performance.
>
> To address this limitation, inner header hash can be used to enable the device to advertise
> the capability to calculate the hash for the inner packet, regaining better receive performance.
>
> Fixes: https://github.com/oasis-tcs/virtio-spec/issues/173
>
> Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
> Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> Reviewed-by: Parav Pandit <parav@nvidia.com>
> ---
> v16->v17:
> 	1. Some small rewrites. @Parav Pandit
> 	2. Add Parav's Reviewed-by tag (Thanks!).
>
> v15->v16:
> 	1. Remove the hash_option. In order to delimit the inner header hash and RSS
> 	   configuration, the ability to configure the outer src udp port hash is given
> 	   to RSS. This is orthogonal to inner header hash, which will be done in the
> 	   RSS capability extension topic (considered as an RSS extension together
> 	   with the symmetric toeplitz hash algorithm, etc.). @Parav Pandit @Michael S . Tsirkin
> 	2. Fix a 'field' typo. @Parav Pandit
>
> v14->v15:
> 	1. Add tunnel hash option suggested by @Michael S . Tsirkin
> 	2. Adjust some descriptions.
>
> v13->v14:
> 	1. Move supported_hash_tunnel_types from config space into cvq command. @Parav Pandit
> 	2. Rebase to master branch.
> 	3. Some minor modifications.
>
> v12->v13:
> 	1. Add a GET command for hash_tunnel_types. @Parav Pandit
> 	2. Add tunneling protocol explanation. @Jason Wang
> 	3. Add comments on some usage scenarios for inner hash.
>
> v11->v12:
> 	1. Add a command VIRTIO_NET_CTRL_MQ_TUNNEL_CONFIG.
> 	2. Refine the commit log. @Michael S . Tsirkin
> 	3. Add some tunnel types.
>
> v10->v11:
> 	1. Revise commit log for clarity for readers.
> 	2. Some modifications to avoid undefined terms. @Parav Pandit
> 	3. Change VIRTIO_NET_F_HASH_TUNNEL dependency. @Parav Pandit
> 	4. Add the normative statements. @Parav Pandit
>
> v9->v10:
> 	1. Removed hash_report_tunnel related information. @Parav Pandit
> 	2. Re-describe the limitations of QoS for tunneling.
> 	3. Some clarification.
>
> v8->v9:
> 	1. Merge hash_report_tunnel_types into hash_report. @Parav Pandit
> 	2. Add tunnel security section. @Michael S . Tsirkin
> 	3. Add VIRTIO_NET_F_HASH_REPORT_TUNNEL.
> 	4. Fix some typos.
> 	5. Add more tunnel types. @Michael S . Tsirkin
>
> v7->v8:
> 	1. Add supported_hash_tunnel_types. @Jason Wang, @Parav Pandit
> 	2. Change hash_report_tunnel to hash_report_tunnel_types. @Parav Pandit
> 	3. Removed re-definition for inner packet hashing. @Parav Pandit
> 	4. Fix some typos. @Michael S . Tsirkin
> 	5. Clarify some sentences. @Michael S . Tsirkin
>
> v6->v7:
> 	1. Modify the wording of some sentences for clarity. @Michael S. Tsirkin
> 	2. Fix some syntax issues. @Michael S. Tsirkin
>
> v5->v6:
> 	1. Fix some syntax and capitalization issues. @Michael S. Tsirkin
> 	2. Use encapsulated/encaptulation uniformly. @Michael S. Tsirkin
> 	3. Move the links to introduction section. @Michael S. Tsirkin
> 	4. Clarify some sentences. @Michael S. Tsirkin
>
> v4->v5:
> 	1. Clarify some paragraphs. @Cornelia Huck
> 	2. Fix the u8 type. @Cornelia Huck
>
> v3->v4:
> 	1. Rename VIRTIO_NET_F_HASH_GRE_VXLAN_GENEVE_INNER to VIRTIO_NET_F_HASH_TUNNEL. @Jason Wang
> 	2. Make things clearer. @Jason Wang @Michael S. Tsirkin
> 	3. Keep the possibility to use inner hash for automatic receive steering. @Jason Wang
> 	4. Add the "Tunnel packet" paragraph to avoid repeating the GRE etc. many times. @Michael S. Tsirkin
>
> v2->v3:
> 	1. Add a feature bit for GRE/VXLAN/GENEVE inner hash. @Jason Wang
> 	2. Chang \field{hash_tunnel} to \field{hash_report_tunnel}. @Jason Wang, @Michael S. Tsirkin
>
> v1->v2:
> 	1. Remove the patch for the bitmask fix. @Michael S. Tsirkin
> 	2. Clarify some paragraphs. @Jason Wang
> 	3. Add \field{hash_tunnel} and VIRTIO_NET_HASH_REPORT_GRE. @Yuri Benditovich
>
>   device-types/net/description.tex        | 161 ++++++++++++++++++++++++
>   device-types/net/device-conformance.tex |   1 +
>   device-types/net/driver-conformance.tex |   1 +
>   introduction.tex                        |  40 ++++++
>   4 files changed, 203 insertions(+)
>
> diff --git a/device-types/net/description.tex b/device-types/net/description.tex
> index 3030222..6bf65ff 100644
> --- a/device-types/net/description.tex
> +++ b/device-types/net/description.tex
> @@ -88,6 +88,8 @@ \subsection{Feature bits}\label{sec:Device Types / Network Device / Feature bits
>   \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through control
>       channel.
>   
> +\item[VIRTIO_NET_F_HASH_TUNNEL(51)] Device supports inner header hash for tunnel-encapsulated packets.
> +
>   \item[VIRTIO_NET_F_VQ_NOTF_COAL(52)] Device supports virtqueue notification coalescing.
>   
>   \item[VIRTIO_NET_F_NOTF_COAL(53)] Device supports notifications coalescing.
> @@ -147,6 +149,7 @@ \subsubsection{Feature bit requirements}\label{sec:Device Types / Network Device
>   \item[VIRTIO_NET_F_RSC_EXT] Requires VIRTIO_NET_F_HOST_TSO4 or VIRTIO_NET_F_HOST_TSO6.
>   \item[VIRTIO_NET_F_RSS] Requires VIRTIO_NET_F_CTRL_VQ.
>   \item[VIRTIO_NET_F_VQ_NOTF_COAL] Requires VIRTIO_NET_F_CTRL_VQ.
> +\item[VIRTIO_NET_F_HASH_TUNNEL] Requires VIRTIO_NET_F_CTRL_VQ along with VIRTIO_NET_F_RSS and/or VIRTIO_NET_F_HASH_REPORT.
>   \end{description}
>   
>   \subsubsection{Legacy Interface: Feature bits}\label{sec:Device Types / Network Device / Feature bits / Legacy Interface: Feature bits}
> @@ -869,6 +872,7 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
>   If the feature VIRTIO_NET_F_RSS was negotiated:
>   \begin{itemize}
>   \item The device uses \field{hash_types} of the virtio_net_rss_config structure as 'Enabled hash types' bitmask.
> +\item The device uses \field{hash_tunnel_types} of the virtnet_hash_tunnel_config_get structure as 'Enabled encapsulation hash types' bitmask if VIRTIO_NET_F_HASH_TUNNEL was negotiated.
>   \item The device uses a key as defined in \field{hash_key_data} and \field{hash_key_length} of the virtio_net_rss_config structure (see
>   \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / Setting RSS parameters}).
>   \end{itemize}
> @@ -876,6 +880,7 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
>   If the feature VIRTIO_NET_F_RSS was not negotiated:
>   \begin{itemize}
>   \item The device uses \field{hash_types} of the virtio_net_hash_config structure as 'Enabled hash types' bitmask.
> +\item The device uses \field{hash_tunnel_types} of the virtnet_hash_tunnel_config_get structure as 'Enabled encapsulation hash types' bitmask if VIRTIO_NET_F_HASH_TUNNEL was negotiated.
>   \item The device uses a key as defined in \field{hash_key_data} and \field{hash_key_length} of the virtio_net_hash_config structure (see
>   \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode / Hash calculation}).
>   \end{itemize}
> @@ -891,6 +896,7 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
>   
>   \subparagraph{Supported/enabled hash types}
>   \label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled hash types}
> +This paragraph relies on definitions from \hyperref[intro:IP]{[IP]}, \hyperref[intro:UDP]{[UDP]} and \hyperref[intro:TCP]{[TCP]}.
>   Hash types applicable for IPv4 packets:
>   \begin{lstlisting}
>   #define VIRTIO_NET_HASH_TYPE_IPv4              (1 << 0)
> @@ -1001,6 +1007,161 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
>   (see \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / IPv6 packets without extension header}).
>   \end{itemize}
>   
> +\paragraph{Inner Header Hash}
> +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Inner Header Hash}
> +
> +If VIRTIO_NET_F_HASH_TUNNEL has been negotiated, the driver can send commands VIRTIO_NET_CTRL_HASH_TUNNEL_SET
> +and VIRTIO_NET_CTRL_HASH_TUNNEL_GET for the inner header hash configuration.
> +
> +struct virtnet_hash_tunnel_config_set {
> +    le32 hash_tunnel_types;
> +};
> +
> +struct virtnet_hash_tunnel_config_get {
> +    le32 supported_hash_tunnel_types;
> +    le32 hash_tunnel_types;
> +};
> +
> +#define VIRTIO_NET_CTRL_HASH_TUNNEL 7
> + #define VIRTIO_NET_CTRL_HASH_TUNNEL_SET 0
> + #define VIRTIO_NET_CTRL_HASH_TUNNEL_GET 1
> +
> +Field \field{supported_hash_tunnel_types} provided by the device indicates that the device supports inner header hash for these encapsulation types.
> +\field{supported_hash_tunnel_types} contains the bitmask of supported tunnel hash types. See \ref{sec:Device Types / Network Device / Device Operation / Processing
> +of Incoming Packets / Hash calculation for incoming packets / Supported/enabled encapsulation hash types}.
> +
> +Field \field{hash_tunnel_types} contains the bitmask of configured tunnel hash types.
> +See \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled encapsulation hash types}.
> +
> +The class VIRTIO_NET_CTRL_HASH_TUNNEL has the following commands:
> +\begin{itemize}
> +\item VIRTIO_NET_CTRL_HASH_TUNNEL_SET: set \field{hash_tunnel_types} for the device using the virtnet_hash_tunnel_config_set structure, which is read-only for the device.
> +\item VIRTIO_NET_CTRL_HASH_TUNNEL_GET: get \field{hash_tunnel_types} and \field{supported_hash_tunnel_types} from the device using the virtnet_hash_tunnel_config_get
> +      structure, which is write-only for the device.
> +\end{itemize}
> +
> +\subparagraph{Tunnel/Encapsulated packet}
> +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Tunnel/Encapsulated packet}
> +
> +A tunnel packet is encapsulated from the original packet based on the tunneling protocol (only a single level of
> +encapsulation is currently supported). The encapsulated packet contains an outer header and an inner header, and
> +the device calculates the hash over either the inner header or the outer header.
> +
> +If VIRTIO_NET_F_HASH_TUNNEL is negotiated and a received encapsulated packet's outer header matches one of the
> +configured \field{hash_tunnel_types}, the hash of the inner header is calculated.
> +
> +Supported encapsulated packet types:
> +\begin{itemize}
> +\item The outer header of the following encapsulation types does not contain the transport protocol:
> +\begin{itemize}
> +\item \hyperref[intro:ipip]{[IPIP]}: the outer header is over IPv4 and the inner header is over IPv4.
> +\item \hyperref[intro:nvgre]{[NVGRE]}: the outer header is over IPv4/IPv6 and the inner header is over IPv4/IPv6.
> +\item \hyperref[intro:gre_rfc2784]{[GRE_rfc2784]}: the outer header is over IPv4 and the inner header is over IPv4.
> +\item \hyperref[intro:gre_rfc2890]{[GRE_rfc2890]}: the outer header is over IPv4 and the inner header is over IPv4.
> +\item \hyperref[intro:gre_rfc7676]{[GRE_rfc7676]}: the outer header is over IPv4/IPv6 and the inner header is over IPv4/IPv6.
> +\end{itemize}
> +\item The outer header of the following encapsulation types uses UDP as the transport protocol:
> +\begin{itemize}
> +\item \hyperref[intro:vxlan]{[VXLAN]}: the outer header is over IPv4/IPv6 and the inner header is over IPv4/IPv6.
> +\item \hyperref[intro:geneve]{[GENEVE]}: the outer header is over IPv4/IPv6 and the inner header is over IPv4/IPv6.
> +\item \hyperref[intro:vxlan_gpe]{[VXLAN-GPE]}: the outer header is over IPv4/IPv6 and the inner header is over IPv4/IPv6.
> +\item \hyperref[intro:gre_in_udp_rfc8086]{[GRE-in-UDP]}: the outer header is over IPv4/IPv6 and the inner header is over IPv4/IPv6.
> +\end{itemize}
> +\end{itemize}
> +
> +If VIRTIO_NET_HASH_TUNNEL_TYPE_NONE is set or the encapsulation type is not included in the configured \field{hash_tunnel_types},
> +the hash of the outer header is calculated for the received encapsulated packet.
> +
> +The hash is calculated for the received non-encapsulated packet as if VIRTIO_NET_F_HASH_TUNNEL was not negotiated.
> +
> +\subparagraph{Supported/enabled encapsulation hash types}
> +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled encapsulation hash types}
> +
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TUNNEL_TYPE_NONE        (1 << 0)
> +\end{lstlisting}
> +
> +Supported encapsulation hash types:
> +Hash type applicable for inner payload of the \hyperref[intro:gre_rfc2784]{[GRE_rfc2784]} packet:
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TUNNEL_TYPE_GRE_2784    (1 << 1)
> +\end{lstlisting}
> +Hash type applicable for inner payload of the \hyperref[intro:gre_rfc2890]{[GRE_rfc2890]} packet:
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TUNNEL_TYPE_GRE_2890    (1 << 2)
> +\end{lstlisting}
> +Hash type applicable for inner payload of the \hyperref[intro:gre_rfc7676]{[GRE_rfc7676]} packet:
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TUNNEL_TYPE_GRE_7676    (1 << 3)
> +\end{lstlisting}
> +Hash type applicable for inner payload of the \hyperref[intro:gre_in_udp_rfc8086]{[GRE-in-UDP]} packet:
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TUNNEL_TYPE_GRE_UDP     (1 << 4)
> +\end{lstlisting}
> +Hash type applicable for inner payload of the \hyperref[intro:vxlan]{[VXLAN]} packet:
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TUNNEL_TYPE_VXLAN       (1 << 5)
> +\end{lstlisting}
> +Hash type applicable for inner payload of the \hyperref[intro:vxlan_gpe]{[VXLAN-GPE]} packet:
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TUNNEL_TYPE_VXLAN_GPE   (1 << 6)
> +\end{lstlisting}
> +Hash type applicable for inner payload of the \hyperref[intro:geneve]{[GENEVE]} packet:
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TUNNEL_TYPE_GENEVE      (1 << 7)
> +\end{lstlisting}
> +Hash type applicable for inner payload of the \hyperref[intro:ipip]{[IPIP]} packet:
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TUNNEL_TYPE_IPIP        (1 << 8)
> +\end{lstlisting}
> +Hash type applicable for inner payload of the \hyperref[intro:nvgre]{[NVGRE]} packet:
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TUNNEL_TYPE_NVGRE       (1 << 9)
> +\end{lstlisting}
> +
> +\subparagraph{Advice}
> +Usage scenarios of inner header hash (but not limited to):
> +\begin{itemize}
> +\item Legacy tunneling protocols that lack entropy in the outer header use inner header hash to hash flows
> +      with the same outer header but different inner headers to different queues for better-receiving performance.
> +\item In scenarios where the same flow passing through different tunnels is expected to be received in the same queue,
> +      to utilize warm caches, to have less locking etc. are optimized to obtain receiving performance.
> +\end{itemize}
> +
> +For scenarios with sufficient outer entropy or no inner header hash requirements, inner header hash may not be needed:
> +A tunnel is often expected to isolate the external network from the internal one. By completely ignoring entropy
> +in the outer header and replacing it with entropy from the inner header, for hash calculations, this expectation
> +might be violated to a certain extent, depending on how the hash is used. When the hash use is limited to RSS queue
> +selection, inner header hash may have quality of service (QoS) limitations.
> +
> +Possible mitigations:
> +\begin{itemize}
> +\item Use a tool with good forwarding performance to keep the receive queue from dropping packets.
> +\item If the QoS is unavailable, the driver can set \field{hash_tunnel_types} to VIRTIO_NET_HASH_TUNNEL_TYPE_NONE
> +      to disable inner header hash for encapsulated packets.
> +\item Perform appropriate QoS before packets consume the receive buffers of the receive queues.
> +\end{itemize}
> +
> +\devicenormative{\subparagraph}{Inner Header Hash}{Device Types / Network Device / Device Operation / Control Virtqueue / Inner Header Hash}
> +
> +The device MUST calculate the hash on the outer header if the type of the received encapsulated packet does not match
> +any value of the configured \field{hash_tunnel_types}.
> +
> +The device MUST respond to the VIRTIO_NET_CTRL_HASH_TUNNEL_SET command with VIRTIO_NET_ERR if the device receives
> +an unsupported or unrecognized VIRTIO_NET_HASH_TUNNEL_TYPE_ flag.
> +
> +The device MUST provide the values of \field{supported_hash_tunnel_types} if it offers the VIRTIO_NET_F_HASH_TUNNEL feature.
> +
> +Upon reset, the device MUST initialize \field{hash_tunnel_type} to 0.
> +
> +\drivernormative{\subparagraph}{Inner Header Hash}{Device Types / Network Device / Device Operation / Control Virtqueue / Inner Header Hash}
> +
> +The driver MUST have negotiated the VIRTIO_NET_F_HASH_TUNNEL feature when issuing commands VIRTIO_NET_CTRL_HASH_TUNNEL_SET and VIRTIO_NET_CTRL_HASH_TUNNEL_GET.
> +
> +The driver MUST ignore the values received from the VIRTIO_NET_CTRL_HASH_TUNNEL_GET command if the device responds with VIRTIO_NET_ERR.
> +
> +The driver MUST NOT set any VIRTIO_NET_HASH_TUNNEL_TYPE_ flags which are not supported by the device.
> +
>   \paragraph{Hash reporting for incoming packets}
>   \label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash reporting for incoming packets}
>   
> diff --git a/device-types/net/device-conformance.tex b/device-types/net/device-conformance.tex
> index 54f6783..f88f48b 100644
> --- a/device-types/net/device-conformance.tex
> +++ b/device-types/net/device-conformance.tex
> @@ -14,4 +14,5 @@
>   \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode}
>   \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS processing}
>   \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Notifications Coalescing}
> +\item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Inner Header Hash}
>   \end{itemize}
> diff --git a/device-types/net/driver-conformance.tex b/device-types/net/driver-conformance.tex
> index 97d0cc1..9d853d9 100644
> --- a/device-types/net/driver-conformance.tex
> +++ b/device-types/net/driver-conformance.tex
> @@ -14,4 +14,5 @@
>   \item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration / Setting Offloads State}
>   \item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) }
>   \item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Notifications Coalescing}
> +\item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Inner Header Hash}
>   \end{itemize}
> diff --git a/introduction.tex b/introduction.tex
> index b7155bf..3f34950 100644
> --- a/introduction.tex
> +++ b/introduction.tex
> @@ -102,6 +102,46 @@ \section{Normative References}\label{sec:Normative References}
>       Standards for Efficient Cryptography Group(SECG), ``SEC1: Elliptic Cureve Cryptography'', Version 1.0, September 2000.
>   	\newline\url{https://www.secg.org/sec1-v2.pdf}\\
>   
> +	\phantomsection\label{intro:gre_rfc2784}\textbf{[GRE_rfc2784]} &
> +    Generic Routing Encapsulation. This protocol is only specified for IPv4 and used as either the payload or delivery protocol.
> +	\newline\url{https://datatracker.ietf.org/doc/rfc2784/}\\
> +	\phantomsection\label{intro:gre_rfc2890}\textbf{[GRE_rfc2890]} &
> +    Key and Sequence Number Extensions to GRE \ref{intro:gre_rfc2784}. This protocol describes extensions by which two fields, Key and
> +    Sequence Number, can be optionally carried in the GRE Header \ref{intro:gre_rfc2784}.
> +	\newline\url{https://www.rfc-editor.org/rfc/rfc2890}\\
> +	\phantomsection\label{intro:gre_rfc7676}\textbf{[GRE_rfc7676]} &
> +    IPv6 Support for Generic Routing Encapsulation (GRE). This protocol is specified for IPv6 and used as either the payload or
> +    delivery protocol. Note that this does not change the GRE header format or any behaviors specified by RFC 2784 or RFC 2890.
> +	\newline\url{https://datatracker.ietf.org/doc/rfc7676/}\\
> +	\phantomsection\label{intro:gre_in_udp_rfc8086}\textbf{[GRE-in-UDP]} &
> +    GRE-in-UDP Encapsulation. This specifies a method of encapsulating network protocol packets within GRE and UDP headers.
> +    This GRE-in-UDP encapsulation allows the UDP source port field to be used as an entropy field. This protocol is specified for IPv4 and IPv6,
> +    and used as either the payload or delivery protocol.
> +	\newline\url{https://www.rfc-editor.org/rfc/rfc8086}\\
> +	\phantomsection\label{intro:vxlan}\textbf{[VXLAN]} &
> +    Virtual eXtensible Local Area Network.
> +	\newline\url{https://datatracker.ietf.org/doc/rfc7348/}\\
> +	\phantomsection\label{intro:vxlan-gpe}\textbf{[VXLAN-GPE]} &
> +    Generic Protocol Extension for VXLAN. This protocol describes extending Virtual eXtensible Local Area Network (VXLAN) via changes to the VXLAN header.
> +	\newline\url{https://www.ietf.org/archive/id/draft-ietf-nvo3-vxlan-gpe-12.txt}\\
> +	\phantomsection\label{intro:geneve}\textbf{[GENEVE]} &
> +    Generic Network Virtualization Encapsulation.
> +	\newline\url{https://datatracker.ietf.org/doc/rfc8926/}\\
> +	\phantomsection\label{intro:ipip}\textbf{[IPIP]} &
> +    IP Encapsulation within IP.
> +	\newline\url{https://www.rfc-editor.org/rfc/rfc2003}\\
> +	\phantomsection\label{intro:nvgre}\textbf{[NVGRE]} &
> +    NVGRE: Network Virtualization Using Generic Routing Encapsulation
> +	\newline\url{https://www.rfc-editor.org/rfc/rfc7637.html}\\
> +	\phantomsection\label{intro:IP}\textbf{[IP]} &
> +    INTERNET PROTOCOL
> +	\newline\url{https://www.rfc-editor.org/rfc/rfc791}\\
> +	\phantomsection\label{intro:UDP}\textbf{[UDP]} &
> +    User Datagram Protocol
> +	\newline\url{https://www.rfc-editor.org/rfc/rfc768}\\
> +	\phantomsection\label{intro:TCP}\textbf{[TCP]} &
> +    TRANSMISSION CONTROL PROTOCOL
> +	\newline\url{https://www.rfc-editor.org/rfc/rfc793}\\
>   \end{longtable}
>   
>   \section{Non-Normative References}


---------------------------------------------------------------------
To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org
For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org