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Website updates for WinDSR / WinOverlay beta support
Signed-off-by: Mark Rossetti <[email protected]> Co-authored-by: Tim Bannister <[email protected]>
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content/en/docs/concepts/services-networking/windows-networking.md

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@@ -93,6 +93,15 @@ The following IPAM options are supported on Windows:
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* [azure-vnet-ipam](https://github.com/Azure/azure-container-networking/blob/master/docs/ipam.md) (for azure-cni only)
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* [Windows Server IPAM](https://docs.microsoft.com/windows-server/networking/technologies/ipam/ipam-top) (fallback option if no IPAM is set)
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## Direct Server Return (DSR) {#dsr}
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{{< feature-state for_k8s_version="v1.33" state="beta" >}}
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Load balancing mode where the IP address fixups and the LBNAT occurs at the container vSwitch port directly; service traffic arrives with the source IP set as the originating pod IP.
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This provides performance optimizations by allowing the return traffic routed through load balancers to bypass the load balancer and respond directly to the client; reducing load on the load balancer and also reducing overall latency.
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For more information, read
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[Direct Server Return (DSR) in a nutshell](https://techcommunity.microsoft.com/blog/networkingblog/direct-server-return-dsr-in-a-nutshell/693710).
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## Load balancing and Services
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A Kubernetes {{< glossary_tooltip text="Service" term_id="service" >}} is an abstraction
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| Feature | Description | Minimum Supported Windows OS build | How to enable |
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| ------- | ----------- | -------------------------- | ------------- |
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| Session affinity | Ensures that connections from a particular client are passed to the same Pod each time. | Windows Server 2022 | Set `service.spec.sessionAffinity` to "ClientIP" |
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| Direct Server Return (DSR) | Load balancing mode where the IP address fixups and the LBNAT occurs at the container vSwitch port directly; service traffic arrives with the source IP set as the originating pod IP. | Windows Server 2019 | Set the following flags in kube-proxy: `--feature-gates="WinDSR=true" --enable-dsr=true` |
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| Direct Server Return (DSR) | See [DSR](#dsr) notes above. | Windows Server 2019 | Set the following command line argument (assuming version {{< skew currentVersion >}}): ` --enable-dsr=true` |
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| Preserve-Destination | Skips DNAT of service traffic, thereby preserving the virtual IP of the target service in packets reaching the backend Pod. Also disables node-node forwarding. | Windows Server, version 1903 | Set `"preserve-destination": "true"` in service annotations and enable DSR in kube-proxy. |
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| IPv4/IPv6 dual-stack networking | Native IPv4-to-IPv4 in parallel with IPv6-to-IPv6 communications to, from, and within a cluster | Windows Server 2019 | See [IPv4/IPv6 dual-stack](/docs/concepts/services-networking/dual-stack/#windows-support) |
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| Client IP preservation | Ensures that source IP of incoming ingress traffic gets preserved. Also disables node-node forwarding. | Windows Server 2019 | Set `service.spec.externalTrafficPolicy` to "Local" and enable DSR in kube-proxy |
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{{< /table >}}
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{{< warning >}}
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There are known issue with NodePort Services on overlay networking, if the destination node is running Windows Server 2022.
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To avoid the issue entirely, you can configure the service with `externalTrafficPolicy: Local`.
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There are known issues with Pod to Pod connectivity on l2bridge network on Windows Server 2022 with KB5005619 or higher installed.
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To workaround the issue and restore Pod to Pod connectivity, you can disable the WinDSR feature in kube-proxy.
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These issues require OS fixes.
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Please follow https://github.com/microsoft/Windows-Containers/issues/204 for updates.
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{{< /warning >}}
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## Limitations
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The following networking functionality is _not_ supported on Windows nodes:

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