diff --git a/src/ca/legacy/pcas/generic/caServerI.cc b/src/ca/legacy/pcas/generic/caServerI.cc
index af7ece1eb..13e01ed55 100644
--- a/src/ca/legacy/pcas/generic/caServerI.cc
+++ b/src/ca/legacy/pcas/generic/caServerI.cc
@@ -141,6 +141,38 @@ caStatus caServerI::attachInterface ( const caNetAddr & addrIn,
     return S_cas_success;
 }
 
+void caServerI::addMCast(const osiSockAddr& addr)
+{
+#ifdef IP_ADD_MEMBERSHIP
+    epicsGuard < epicsMutex > locker ( this->mutex );
+    tsDLIter < casIntfOS > iter = this->intfList.firstIter ();
+    while ( iter.valid () ) {
+        struct ip_mreq mreq;
+
+        memset(&mreq, 0, sizeof(mreq));
+        mreq.imr_interface = iter->serverAddress().getSockIP().sin_addr;
+        mreq.imr_multiaddr = addr.ia.sin_addr;
+
+        if(setsockopt(iter->casDGIntfIO::getFD(), IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq))!=0)
+        {
+            struct sockaddr_in temp;
+            char name[40];
+            char sockErrBuf[64];
+            temp.sin_family = AF_INET;
+            temp.sin_addr = mreq.imr_multiaddr;
+            temp.sin_port = addr.ia.sin_port;
+            epicsSocketConvertErrnoToString (
+                sockErrBuf, sizeof ( sockErrBuf ) );
+            ipAddrToDottedIP (&temp, name, sizeof(name));
+            fprintf(stderr, "CAS: Socket mcast join %s failed with \"%s\"\n",
+                name, sockErrBuf );
+        }
+
+        iter++;
+    }
+#endif
+}
+
 void caServerI::sendBeacon ( ca_uint32_t beaconNo )
 {
     epicsGuard < epicsMutex > locker ( this->mutex );
diff --git a/src/ca/legacy/pcas/generic/caServerI.h b/src/ca/legacy/pcas/generic/caServerI.h
index 6037d8c20..344f6393b 100644
--- a/src/ca/legacy/pcas/generic/caServerI.h
+++ b/src/ca/legacy/pcas/generic/caServerI.h
@@ -103,6 +103,8 @@ private:
     caStatus attachInterface ( const caNetAddr & addr, bool autoBeaconAddr,
             bool addConfigAddr );
 
+    virtual void addMCast(const osiSockAddr&);
+
     void sendBeacon ( ca_uint32_t beaconNo );
 
     caServerI ( const caServerI & );
diff --git a/src/ca/legacy/pcas/io/bsdSocket/caServerIO.cc b/src/ca/legacy/pcas/io/bsdSocket/caServerIO.cc
index 5c5da03ff..8e5c356a6 100644
--- a/src/ca/legacy/pcas/io/bsdSocket/caServerIO.cc
+++ b/src/ca/legacy/pcas/io/bsdSocket/caServerIO.cc
@@ -14,6 +14,7 @@
 //
 
 #include <ctype.h>
+#include <list>
 
 #include "epicsSignal.h"
 #include "envDefs.h"
@@ -92,6 +93,9 @@ void caServerIO::locateInterfaces ()
 		autoBeaconAddr = true;
 	}
 
+    typedef std::list<osiSockAddr> mcastAddrs_t;
+    mcastAddrs_t mcastAddrs;
+
 	//
 	// bind to the the interfaces specified - otherwise wildcard
 	// with INADDR_ANY and allow clients to attach from any interface
@@ -114,6 +118,15 @@ void caServerIO::locateInterfaces ()
 					pToken);
 				continue;
 			}
+
+            epicsUInt32 top = ntohl(saddr.sin_addr.s_addr)>>24;
+            if (saddr.sin_family==AF_INET && top>=224 && top<=239) {
+                osiSockAddr oaddr;
+                oaddr.ia = saddr;
+                mcastAddrs.push_back(oaddr);
+                continue;
+            }
+
 			stat = this->attachInterface (caNetAddr(saddr), autoBeaconAddr, configAddrOnceFlag);
 			if (stat) {
 				errMessage(stat, "unable to attach explicit interface");
@@ -131,6 +144,10 @@ void caServerIO::locateInterfaces ()
 			errMessage(stat, "unable to attach any interface");
 		}
 	}
+
+    for (mcastAddrs_t::const_iterator it = mcastAddrs.begin(); it!=mcastAddrs.end(); ++it) {
+        this->addMCast(*it);
+    }
 }
 
 //
diff --git a/src/ca/legacy/pcas/io/bsdSocket/caServerIO.h b/src/ca/legacy/pcas/io/bsdSocket/caServerIO.h
index b24afb5f8..b45903cff 100644
--- a/src/ca/legacy/pcas/io/bsdSocket/caServerIO.h
+++ b/src/ca/legacy/pcas/io/bsdSocket/caServerIO.h
@@ -47,6 +47,8 @@ private:
 	virtual caStatus attachInterface (
         const caNetAddr & addr, bool autoBeaconAddr,
 		bool addConfigAddr ) = 0;
+
+    virtual void addMCast(const osiSockAddr&) = 0;
 };
 
 #endif // caServerIOh