add dlb example

dlb/dlb_example_config.yaml

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+static_resources:
+  listeners:
+  - address:
+      socket_address:
+        address: 0.0.0.0
+        port_value: 10000
+    connection_balance_config:
+      extend_balance:
+        name: envoy.network.connection_balance.dlb
+        typed_config:
+          "@type": type.googleapis.com/envoy.extensions.network.connection_balance.dlb.v3alpha.Dlb
+    filter_chains:
+    - filters:
+      - name: envoy.filters.network.http_connection_manager
+        typed_config:
+          "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
+          codec_type: AUTO
+          stat_prefix: ingress_http
+          route_config:
+            name: local_route
+            virtual_hosts:
+            - name: backend
+              domains:
+              - "*"
+              routes:
+              - match:
+                  prefix: "/"
+                route:
+                  cluster: service1
+          http_filters:
+          - name: envoy.filters.http.router
+            typed_config:
+              "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router
+
+  clusters:
+  - name: service1
+    load_assignment:
+      cluster_name: service1
+      endpoints:
+      - lb_endpoints:
+        - endpoint:
+            address:
+              socket_address:
+                address: 127.0.0.1
+                port_value: 12000

dlb/example.rst

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+.. _install_sandboxes_dlb:
+
+DLB
+===
+
+By enabling connection balancer in Envoy you can balance the connections across the threads and improve performance.
+
+This sandbox provides an example about how to enable DLB connection balanace.
+
+.. note::
+   Please run below command to check your CPU supports DLB:
+
+   .. code-block:: console
+
+   $ lspci -d :2710
+
+   You should get output like below:
+
+   .. code-block:: text
+
+      5a:00.0 Co-processor: Intel Corporation Device 2710
+      6b:00.0 Co-processor: Intel Corporation Device 2710
+      7c:00.0 Co-processor: Intel Corporation Device 2710
+      8d:00.0 Co-processor: Intel Corporation Device 2710
+
+   The output that is not empty means CPU supports DLB. The number and PCIE address of DLB devices vary from CPU to CPU.
+
+   The minimum support kernel version is 5.15.
+
+Step 1: Install DLB Driver
+**************************
+
+You can download the DLB driver release tarball from the `DLB website <https://www.intel.com/content/www/us/en/download/686372/intel-dynamic-load-balancer.html>`_.
+
+To install it refer to `the getting started guide <https://downloadmirror.intel.com/727424/DLB_Driver_User_Guide.pdf>`_.
+
+Step 2: Run Envoy with DLB connection balanace enabled
+******************************************************
+
+With the example configuration Envoy listens on port 10000 and proxies to an upstream server listening on port 12000.
+
+.. literalinclude:: _include/dlb/dlb_example_config.yaml
+ :language: yaml
+ :lines: 7-11
+ :lineno-start: 7
+ :linenos:
+ :caption: :download:`dlb_example_config.yaml <_include/dlb/dlb_example_config.yaml>`
+
+.. code-block:: console
+
+ $ ./envoy --concurrency 2 -c dlb_example_config.yaml --log-level debug &> envoy-dlb.log
+
+After Envoy starts, you should see logs similar to:
+
+.. code-block:: console
+
+ $ grep dlb envoy-dlb.log
+
+.. code-block:: text
+
+  [2024-07-08 10:05:00.113][3596312][info][main] [source/server/server.cc:434]   envoy.network.connection_balance: envoy.network.connection_balance.dlb
+  [2024-07-08 10:05:00.241][3596312][debug][config] [contrib/dlb/source/connection_balancer_impl.cc:92] dlb available resources: domains: 32, LDB queues: 32, LDB ports: 64, ES entries: 2048, Contig ES entries: 2048, LDB credits: 8192, Config LDB credits: 8192, LDB credit pools: 64
+
+Step 3: Run the upstream service
+********************************
+
+.. code-block:: console
+
+ $ docker run -d -p 12000:80 nginx
+
+Step 3: Test
+************
+
+Visit the upstream service by Envoy endpoint:
+
+.. code-block:: console
+
+ $ curl localhost:10000 | grep Welcome
+
+You should get output from Nginx:
+
+.. code-block:: text
+
+  <title>Welcome to nginx!</title>
+
+Check the log, you should see the latest contents similar to:
+
+.. code-block:: text
+
+  [2024-07-08 10:10:48.099][3598062][debug][connection] [contrib/dlb/source/connection_balancer_impl.cc:283] worker_1 dlb send fd 49
+  [2024-07-08 10:10:48.099][3598066][debug][connection] [contrib/dlb/source/connection_balancer_impl.cc:300] worker_3 get dlb event 1
+  [2024-07-08 10:10:48.099][3598066][debug][connection] [contrib/dlb/source/connection_balancer_impl.cc:317] worker_3 dlb recv 49
+  [2024-07-08 10:10:48.099][3598066][debug][connection] [contrib/dlb/source/connection_balancer_impl.cc:297] worker_3 dlb receive none, skip
+
+Above logs show that DLB balanaces a connection from worker 1 to worker 3.
+
+.. seealso::
+   :ref:`DLB connection balanace API <envoy_v3_api_msg_extensions.network.connection_balance.dlb.v3alpha.Dlb>`
+      API and configuration reference for Envoy's DLB connection balanace.
+
+   :ref:`Connection balance configuration <envoy_v3_api_field_config.listener.v3.Listener.connection_balance_config>`
+      Configuration referenc for Envoy's connection balanace.
+
+  `DLB <https://networkbuilders.intel.com/solutionslibrary/queue-management-and-load-balancing-on-intel-architecture>`_
+    The Intel DLB website.