no need to keep generating guids

src/StackExchange.Redis/PhysicalBridge.cs

@@ -255,7 +255,7 @@ internal void KeepAlive()
                     else if (commandMap.IsAvailable(RedisCommand.UNSUBSCRIBE))
                     {
                         msg = Message.Create(-1, CommandFlags.FireAndForget, RedisCommand.UNSUBSCRIBE,
-                            (RedisChannel)Guid.NewGuid().ToByteArray());
+                            (RedisChannel)Multiplexer.UniqueId);
                         msg.SetSource(ResultProcessor.TrackSubscriptions, null);
                     }
                     break;

src/StackExchange.Redis/RedisSubscriber.cs

@@ -349,7 +349,7 @@ private Message CreatePingMessage(CommandFlags flags, out ServerEndPoint server)
             else
             {
                 // can't use regular PING, but we can unsubscribe from something random that we weren't even subscribed to...
-                RedisValue channel = Guid.NewGuid().ToByteArray();
+                RedisValue channel = multiplexer.UniqueId;
                 return ResultProcessor.TimingProcessor.CreateMessage(-1, flags, RedisCommand.UNSUBSCRIBE, channel);
             }
         }

src/StackExchange.Redis/ServerEndPoint.cs

@@ -300,7 +300,7 @@ internal void AutoConfigure(PhysicalConnection connection)
             else if (commandMap.IsAvailable(RedisCommand.SET))
             {
                 // this is a nasty way to find if we are a slave, and it will only work on up-level servers, but...
-                RedisKey key = Guid.NewGuid().ToByteArray();
+                RedisKey key = Multiplexer.UniqueId;
                 msg = Message.Create(0, flags, RedisCommand.SET, key, RedisLiterals.slave_read_only, RedisLiterals.PX, 1, RedisLiterals.NX);
                 msg.SetInternalCall();
                 WriteDirectOrQueueFireAndForget(connection, msg, ResultProcessor.AutoConfigure);