New maximum stream IDs test

README.md

@@ -101,6 +101,18 @@ It technically doesn't support v5, but handles protocol negotiation so that the
 the protocol version to v4 if v5 is requested. This means that any client application using a recent driver that supports
 protocol version v5 can be migrated using the ZDM Proxy (as long as it does not use v5-specific functionality).
 
+ZDM Proxy requires origin and target clusters to have at least one protocol version in common. It is therefore not feasible
+to configure Apache Cassandra 2.0 as origin and 3.x / 4.x as target. Below table displays protocol versions supported by
+various C* versions:
+
+| Apache Cassandra | Protocol Version |
+|------------------|------------------|
+| 2.0              | V2               |
+| 2.1              | V2, V3           |
+| 2.2              | V3, V4           |
+| 3.x              | V3, V4           |
+| 4.x              | V3, V4, V5       |
+
 ---
 :warning: **Thrift is not supported by ZDM Proxy.** If you are using a very old driver or cluster version that only supports Thrift
 then you need to change your client application to use CQL and potentially upgrade your cluster before starting the 
@@ -110,7 +122,8 @@ migration process.
 
 In practice this means that ZDM Proxy supports the following cluster versions (as Origin and / or Target):
 
-- Apache Cassandra from 2.0+ up to (and including) Apache Cassandra 4.x.
+- Apache Cassandra from 2.1+ up to (and including) Apache Cassandra 4.x.
+- Apache Cassandra 2.0 up to 2.1.
 - DataStax Enterprise 4.8+. DataStax Enterprise 4.6 and 4.7 support will be introduced when protocol version v2 is supported.
 - DataStax Astra DB (both Serverless and Classic)
 

integration-tests/connect_test.go

@@ -46,7 +46,9 @@ func TestGoCqlConnect(t *testing.T) {
 	require.Equal(t, "fake", iter.Columns()[0].Name)
 }
 
-func TestProtocolVersionNegotiation(t *testing.T) {
+// Simulacron-based test to make sure that we can handle invalid protocol error and downgrade
+// used protocol on control connection. ORIGIN and TARGET are using the same C* version
+func TestControlConnectionProtocolVersionNegotiation(t *testing.T) {
 	tests := []struct {
 		name                          string
 		clusterVersion                string
@@ -63,13 +65,13 @@ func TestProtocolVersionNegotiation(t *testing.T) {
 			name:                          "Cluster3.0_MaxCCProtoVer4_NegotiatedProtoVer4",
 			clusterVersion:                "3.0",
 			controlConnMaxProtocolVersion: "4",
-			negotiatedProtocolVersion:     primitive.ProtocolVersion4,
+			negotiatedProtocolVersion:     primitive.ProtocolVersion4, // make sure that protocol negotiation does not fail if it is not actually needed
 		},
 		{
-			name:                          "Cluster4.0_MaxCCProtoVer4_NegotiatedProtoVer4",
-			clusterVersion:                "4.0",
-			controlConnMaxProtocolVersion: "4",
-			negotiatedProtocolVersion:     primitive.ProtocolVersion4,
+			name:                          "Cluster3.0_MaxCCProtoVer3_NegotiatedProtoVer3",
+			clusterVersion:                "3.0",
+			controlConnMaxProtocolVersion: "3",
+			negotiatedProtocolVersion:     primitive.ProtocolVersion3, // protocol V3 applied as it is the maximum configured
 		},
 	}
 
@@ -103,7 +105,7 @@ func TestProtocolVersionNegotiation(t *testing.T) {
 			defer cqlClientConn.Close()
 
 			cqlConn, _ := testSetup.Proxy.GetOriginControlConn().GetConnAndContactPoint()
-			negotiatedProto := cqlConn.GetProtocolVersion().Load().(primitive.ProtocolVersion)
+			negotiatedProto := cqlConn.GetProtocolVersion()
 			require.Equal(t, tt.negotiatedProtocolVersion, negotiatedProto)
 
 			queryMsg := &message.Query{