Should not use loopback addresses (#5036)

* fix multi cluster dns docs

* fix multi cluster dns docs

* ignore multicast spelling check

.spelling

@@ -345,6 +345,7 @@ misordered
 Mitigations
 MongoDB
 mongodb
+multicast
 Multicloud
 multicloud
 Multicluster

content/en/blog/2019/multicluster-version-routing/index.md

@@ -299,7 +299,7 @@ spec:
     protocol: http
   resolution: DNS
   addresses:
-  - 127.255.0.3
+  - 224.0.0.3
   endpoints:
   - address: ${CLUSTER2_GW_ADDR}
     labels:
@@ -326,8 +326,9 @@ spec:
 EOF
 {{< /text >}}
 
-The address `127.255.0.3` of the service entry can be any arbitrary unallocated IP.
-Using an IP from the loopback range 127.0.0.0/8 is a good choice.
+The address `224.0.0.3` of the service entry can be any arbitrary unallocated IP.
+Note that loopback range `127.0.0.0/8` should not be used, as it will influence outbound traffic.
+Using an IP from the multicast range 224.0.0.0/4 is a good choice.
 Check out the
 [gateway-connected multicluster example](/docs/setup/install/multicluster/gateways/#configure-the-example-services)
 for more details.

content/en/docs/setup/install/multicluster/gateways/index.md

@@ -264,10 +264,8 @@ running in a second cluster. Before you begin:
     {{< /tip >}}
 
     If the global services have actual VIPs, you can use those, but otherwise we suggest
-    using IPs from the loopback range `127.0.0.0/8` that are not already allocated.
-    These IPs are non-routable outside of a pod.
-    In this example we'll use IPs in `127.255.0.0/16` which avoids conflicting with
-    well known IPs such as `127.0.0.1` (`localhost`).
+    using IPs from the multicast range `224.0.0.0/4` that are not already allocated.
+    These IPs are not loopback addresses and are non-routable outside of a pod.
     Application traffic for these IPs will be captured by the sidecar and routed to the
     appropriate remote service.
 
@@ -294,7 +292,7 @@ running in a second cluster. Before you begin:
       # must be unique for each remote service, within a given cluster.
       # This address need not be routable. Traffic for this IP will be captured
       # by the sidecar and routed appropriately.
-      - 127.255.0.2
+      - 224.0.0.2
       endpoints:
       # This is the routable address of the ingress gateway in cluster2 that
       # sits in front of sleep.foo service. Traffic from the sidecar will be
@@ -365,7 +363,7 @@ spec:
     protocol: http
   resolution: STATIC
   addresses:
-  - 127.255.0.2
+  - 224.0.0.2
   endpoints:
   - address: ${CLUSTER2_GW_ADDR}
     network: external
@@ -399,7 +397,7 @@ spec:
     protocol: http
   resolution: DNS
   addresses:
-  - 127.255.0.2
+  - 224.0.0.2
   endpoints:
   - address: ${CLUSTER2_GW_ADDR}
     network: external
@@ -459,7 +457,7 @@ spec:
   addresses:
   # the IP address to which httpbin.bar.global will resolve to
   # must be unique for each service.
-  - 127.255.0.2
+  - 224.0.0.2
   endpoints:
   - address: ${CLUSTER2_GW_ADDR}
     labels: