diff --git a/src/base/types.hh b/src/base/types.hh
index 5ce778572..3105059ed 100644
--- a/src/base/types.hh
+++ b/src/base/types.hh
@@ -97,6 +97,12 @@ const Addr MaxAddr = (Addr)-1;
 typedef int16_t ThreadID;
 const ThreadID InvalidThreadID = (ThreadID)-1;
 
+/**
+ * Port index/ID type, and a symbolic name for an invalid port id.
+ */
+typedef int16_t PortID;
+const PortID InvalidPortID = (PortID)-1;
+
 class FaultBase;
 template <class T> class RefCountingPtr;
 typedef RefCountingPtr<FaultBase> Fault;
diff --git a/src/cpu/testers/directedtest/RubyDirectedTester.hh b/src/cpu/testers/directedtest/RubyDirectedTester.hh
index 75e72edf8..325c60447 100644
--- a/src/cpu/testers/directedtest/RubyDirectedTester.hh
+++ b/src/cpu/testers/directedtest/RubyDirectedTester.hh
@@ -54,7 +54,7 @@ class RubyDirectedTester : public MemObject
 
       public:
         CpuPort(const std::string &_name, RubyDirectedTester *_tester,
-                Port::PortId _id)
+                PortID _id)
             : MasterPort(_name, _tester, _id), tester(_tester)
         {}
 
diff --git a/src/cpu/testers/rubytest/RubyTester.hh b/src/cpu/testers/rubytest/RubyTester.hh
index 8fbd886b3..ad4b506ac 100644
--- a/src/cpu/testers/rubytest/RubyTester.hh
+++ b/src/cpu/testers/rubytest/RubyTester.hh
@@ -57,7 +57,7 @@ class RubyTester : public MemObject
         // RubyPorts that support both types of requests, separate InstOnly
         // and DataOnly CpuPorts will map to that RubyPort
 
-        CpuPort(const std::string &_name, RubyTester *_tester, PortId _id)
+        CpuPort(const std::string &_name, RubyTester *_tester, PortID _id)
             : MasterPort(_name, _tester, _id), tester(_tester)
         {}
 
diff --git a/src/mem/bridge.hh b/src/mem/bridge.hh
index 0160b8b9e..7342f4a9f 100644
--- a/src/mem/bridge.hh
+++ b/src/mem/bridge.hh
@@ -91,7 +91,7 @@ class Bridge : public MemObject
       public:
 
         Packet::SenderState *origSenderState;
-        Packet::NodeID origSrc;
+        PortID origSrc;
 
         RequestState(PacketPtr _pkt)
             : origSenderState(_pkt->senderState),
diff --git a/src/mem/bus.cc b/src/mem/bus.cc
index 58745326a..e24b54b0e 100644
--- a/src/mem/bus.cc
+++ b/src/mem/bus.cc
@@ -57,7 +57,7 @@ Bus::Bus(const BusParams *p)
     : MemObject(p), clock(p->clock),
       headerCycles(p->header_cycles), width(p->width), tickNextIdle(0),
       drainEvent(NULL), busIdleEvent(this), inRetry(false),
-      defaultPortId(Port::INVALID_PORT_ID),
+      defaultPortID(InvalidPortID),
       useDefaultRange(p->use_default_range),
       defaultBlockSize(p->block_size),
       cachedBlockSize(0), cachedBlockSizeValid(false)
@@ -82,9 +82,9 @@ Bus::Bus(const BusParams *p)
     // see if we have a default slave device connected and if so add
     // our corresponding master port
     if (p->port_default_connection_count) {
-        defaultPortId = masterPorts.size();
+        defaultPortID = masterPorts.size();
         std::string portName = csprintf("%s-default", name());
-        MasterPort* bp = new BusMasterPort(portName, this, defaultPortId);
+        MasterPort* bp = new BusMasterPort(portName, this, defaultPortID);
         masterPorts.push_back(bp);
     }
 
@@ -105,7 +105,7 @@ Bus::getMasterPort(const std::string &if_name, int idx)
         // the master port index translates directly to the vector position
         return *masterPorts[idx];
     } else  if (if_name == "default") {
-        return *masterPorts[defaultPortId];
+        return *masterPorts[defaultPortID];
     } else {
         return MemObject::getMasterPort(if_name, idx);
     }
@@ -318,7 +318,7 @@ Bus::recvTimingSnoopReq(PacketPtr pkt)
     assert(pkt->isExpressSnoop());
 
     // forward to all snoopers
-    forwardTiming(pkt, Port::INVALID_PORT_ID);
+    forwardTiming(pkt, InvalidPortID);
 
     // a snoop request came from a connected slave device (one of
     // our master ports), and if it is not coming from the slave
@@ -347,7 +347,7 @@ Bus::recvTimingSnoopResp(PacketPtr pkt)
             src_port->name(), pkt->cmdString(), pkt->getAddr());
 
     // get the destination from the packet
-    Packet::NodeID dest = pkt->getDest();
+    PortID dest = pkt->getDest();
 
     // responses are never express snoops
     assert(!pkt->isExpressSnoop());
@@ -410,7 +410,7 @@ Bus::succeededTiming(Tick busy_time)
 }
 
 void
-Bus::forwardTiming(PacketPtr pkt, int exclude_slave_port_id)
+Bus::forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id)
 {
     for (SlavePortIter s = snoopPorts.begin(); s != snoopPorts.end(); ++s) {
         SlavePort *p = *s;
@@ -418,7 +418,7 @@ Bus::forwardTiming(PacketPtr pkt, int exclude_slave_port_id)
         // (corresponding to our own slave port that is also in
         // snoopPorts) and should not send it back to where it came
         // from
-        if (exclude_slave_port_id == Port::INVALID_PORT_ID ||
+        if (exclude_slave_port_id == InvalidPortID ||
             p->getId() != exclude_slave_port_id) {
             // cache is not allowed to refuse snoop
             p->sendTimingSnoopReq(pkt);
@@ -481,7 +481,7 @@ Bus::retryWaiting()
 }
 
 void
-Bus::recvRetry(Port::PortId id)
+Bus::recvRetry(PortID id)
 {
     // we got a retry from a peer that we tried to send something to
     // and failed, but we sent it on the account of someone else, and
@@ -500,14 +500,12 @@ Bus::recvRetry(Port::PortId id)
     }
 }
 
-int
+PortID
 Bus::findPort(Addr addr)
 {
     /* An interval tree would be a better way to do this. --ali. */
-    int dest_id;
-
-    dest_id = checkPortCache(addr);
-    if (dest_id != Port::INVALID_PORT_ID)
+    PortID dest_id = checkPortCache(addr);
+    if (dest_id != InvalidPortID)
         return dest_id;
 
     // Check normal port ranges
@@ -524,13 +522,13 @@ Bus::findPort(Addr addr)
         for (AddrRangeIter i = defaultRange.begin(); i != a_end; i++) {
             if (*i == addr) {
                 DPRINTF(Bus, "  found addr %#llx on default\n", addr);
-                return defaultPortId;
+                return defaultPortID;
             }
         }
-    } else if (defaultPortId != Port::INVALID_PORT_ID) {
+    } else if (defaultPortID != InvalidPortID) {
         DPRINTF(Bus, "Unable to find destination for addr %#llx, "
                 "will use default port\n", addr);
-        return defaultPortId;
+        return defaultPortID;
     }
 
     // we should use the range for the default port and it did not
@@ -560,7 +558,7 @@ Bus::recvAtomic(PacketPtr pkt)
 
     // even if we had a snoop response, we must continue and also
     // perform the actual request at the destination
-    int dest_id = findPort(pkt->getAddr());
+    PortID dest_id = findPort(pkt->getAddr());
 
     // forward the request to the appropriate destination
     Tick response_latency = masterPorts[dest_id]->sendAtomic(pkt);
@@ -586,7 +584,7 @@ Bus::recvAtomicSnoop(PacketPtr pkt)
 
     // forward to all snoopers
     std::pair<MemCmd, Tick> snoop_result =
-        forwardAtomic(pkt, Port::INVALID_PORT_ID);
+        forwardAtomic(pkt, InvalidPortID);
     MemCmd snoop_response_cmd = snoop_result.first;
     Tick snoop_response_latency = snoop_result.second;
 
@@ -598,12 +596,12 @@ Bus::recvAtomicSnoop(PacketPtr pkt)
 }
 
 std::pair<MemCmd, Tick>
-Bus::forwardAtomic(PacketPtr pkt, int exclude_slave_port_id)
+Bus::forwardAtomic(PacketPtr pkt, PortID exclude_slave_port_id)
 {
     // the packet may be changed on snoops, record the original source
     // and command to enable us to restore it between snoops so that
     // additional snoops can take place properly
-    Packet::NodeID orig_src_id = pkt->getSrc();
+    PortID orig_src_id = pkt->getSrc();
     MemCmd orig_cmd = pkt->cmd;
     MemCmd snoop_response_cmd = MemCmd::InvalidCmd;
     Tick snoop_response_latency = 0;
@@ -614,7 +612,7 @@ Bus::forwardAtomic(PacketPtr pkt, int exclude_slave_port_id)
         // (corresponding to our own slave port that is also in
         // snoopPorts) and should not send it back to where it came
         // from
-        if (exclude_slave_port_id == Port::INVALID_PORT_ID ||
+        if (exclude_slave_port_id == InvalidPortID ||
             p->getId() != exclude_slave_port_id) {
             Tick latency = p->sendAtomicSnoop(pkt);
             // in contrast to a functional access, we have to keep on
@@ -662,7 +660,7 @@ Bus::recvFunctional(PacketPtr pkt)
     // there is no need to continue if the snooping has found what we
     // were looking for and the packet is already a response
     if (!pkt->isResponse()) {
-        int dest_id = findPort(pkt->getAddr());
+        PortID dest_id = findPort(pkt->getAddr());
 
         masterPorts[dest_id]->sendFunctional(pkt);
     }
@@ -680,11 +678,11 @@ Bus::recvFunctionalSnoop(PacketPtr pkt)
     }
 
     // forward to all snoopers
-    forwardFunctional(pkt, Port::INVALID_PORT_ID);
+    forwardFunctional(pkt, InvalidPortID);
 }
 
 void
-Bus::forwardFunctional(PacketPtr pkt, int exclude_slave_port_id)
+Bus::forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id)
 {
     for (SlavePortIter s = snoopPorts.begin(); s != snoopPorts.end(); ++s) {
         SlavePort *p = *s;
@@ -692,7 +690,7 @@ Bus::forwardFunctional(PacketPtr pkt, int exclude_slave_port_id)
         // (corresponding to our own slave port that is also in
         // snoopPorts) and should not send it back to where it came
         // from
-        if (exclude_slave_port_id == Port::INVALID_PORT_ID ||
+        if (exclude_slave_port_id == InvalidPortID ||
             p->getId() != exclude_slave_port_id)
             p->sendFunctionalSnoop(pkt);
 
@@ -705,7 +703,7 @@ Bus::forwardFunctional(PacketPtr pkt, int exclude_slave_port_id)
 
 /** Function called by the port when the bus is receiving a range change.*/
 void
-Bus::recvRangeChange(Port::PortId id)
+Bus::recvRangeChange(PortID id)
 {
     AddrRangeList ranges;
     AddrRangeIter iter;
@@ -717,7 +715,7 @@ Bus::recvRangeChange(Port::PortId id)
     DPRINTF(BusAddrRanges, "received RangeChange from device id %d\n", id);
 
     clearPortCache();
-    if (id == defaultPortId) {
+    if (id == defaultPortID) {
         defaultRange.clear();
         // Only try to update these ranges if the user set a default responder.
         if (useDefaultRange) {
@@ -749,7 +747,7 @@ Bus::recvRangeChange(Port::PortId id)
             DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for id %d\n",
                     iter->start, iter->end, id);
             if (portMap.insert(*iter, id) == portMap.end()) {
-                int conflict_id = portMap.find(*iter)->second;
+                PortID conflict_id = portMap.find(*iter)->second;
                 fatal("%s has two ports with same range:\n\t%s\n\t%s\n",
                       name(), masterPorts[id]->getSlavePort().name(),
                       masterPorts[conflict_id]->getSlavePort().name());
@@ -768,7 +766,7 @@ Bus::recvRangeChange(Port::PortId id)
 }
 
 AddrRangeList
-Bus::getAddrRanges(Port::PortId id)
+Bus::getAddrRanges(PortID id)
 {
     AddrRangeList ranges;
 
@@ -809,14 +807,14 @@ Bus::getAddrRanges(Port::PortId id)
 }
 
 bool
-Bus::isSnooping(Port::PortId id) const
+Bus::isSnooping(PortID id) const
 {
     // in essence, answer the question if there are snooping ports
     return !snoopPorts.empty();
 }
 
 unsigned
-Bus::findBlockSize(Port::PortId id)
+Bus::findBlockSize(PortID id)
 {
     if (cachedBlockSizeValid)
         return cachedBlockSize;
diff --git a/src/mem/bus.hh b/src/mem/bus.hh
index 4ccb586e3..b5d7a3801 100644
--- a/src/mem/bus.hh
+++ b/src/mem/bus.hh
@@ -66,6 +66,7 @@
 
 class Bus : public MemObject
 {
+
     /**
      * Declaration of the bus slave port type, one will be
      * instantiated for each of the master interfaces connecting to
@@ -80,7 +81,7 @@ class Bus : public MemObject
       public:
 
         /** Constructor for the BusSlavePort.*/
-        BusSlavePort(const std::string &_name, Bus *_bus, Port::PortId _id)
+        BusSlavePort(const std::string &_name, Bus *_bus, PortID _id)
             : SlavePort(_name, _bus, _id), bus(_bus)
         { }
 
@@ -145,7 +146,7 @@ class Bus : public MemObject
       public:
 
         /** Constructor for the BusMasterPort.*/
-        BusMasterPort(const std::string &_name, Bus *_bus, Port::PortId _id)
+        BusMasterPort(const std::string &_name, Bus *_bus, PortID _id)
             : MasterPort(_name, _bus, _id), bus(_bus)
         { }
 
@@ -213,8 +214,8 @@ class Bus : public MemObject
 
     Event * drainEvent;
 
-    typedef range_map<Addr,int>::iterator PortIter;
-    range_map<Addr, int> portMap;
+    typedef range_map<Addr, PortID>::iterator PortIter;
+    range_map<Addr, PortID> portMap;
 
     AddrRangeList defaultRange;
 
@@ -251,7 +252,7 @@ class Bus : public MemObject
      * @param pkt Packet to forward
      * @param exclude_slave_port_id Id of slave port to exclude
      */
-    void forwardTiming(PacketPtr pkt, Port::PortId exclude_slave_port_id);
+    void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id);
 
     /**
      * Determine if the bus is to be considered occupied when being
@@ -293,7 +294,7 @@ class Bus : public MemObject
      * @return a pair containing the snoop response and snoop latency
      */
     std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
-                                          Port::PortId exclude_slave_port_id);
+                                          PortID exclude_slave_port_id);
 
     /** Function called by the port when the bus is recieving a Functional
         transaction.*/
@@ -311,26 +312,26 @@ class Bus : public MemObject
      * @param pkt Packet to forward
      * @param exclude_slave_port_id Id of slave port to exclude
      */
-    void forwardFunctional(PacketPtr pkt, Port::PortId exclude_slave_port_id);
+    void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id);
 
     /** Timing function called by port when it is once again able to process
      * requests. */
-    void recvRetry(Port::PortId id);
+    void recvRetry(PortID id);
 
     /** Function called by the port when the bus is recieving a range change.*/
-    void recvRangeChange(Port::PortId id);
+    void recvRangeChange(PortID id);
 
     /** Find which port connected to this bus (if any) should be given a packet
      * with this address.
      * @param addr Address to find port for.
      * @return id of port that the packet should be sent out of.
      */
-    int findPort(Addr addr);
+    PortID findPort(Addr addr);
 
     // Cache for the findPort function storing recently used ports from portMap
     struct PortCache {
         bool valid;
-        Port::PortId id;
+        PortID id;
         Addr start;
         Addr end;
     };
@@ -339,7 +340,7 @@ class Bus : public MemObject
 
     // Checks the cache and returns the id of the port that has the requested
     // address within its range
-    inline int checkPortCache(Addr addr) {
+    inline PortID checkPortCache(Addr addr) {
         if (portCache[0].valid && addr >= portCache[0].start &&
             addr < portCache[0].end) {
             return portCache[0].id;
@@ -353,7 +354,7 @@ class Bus : public MemObject
             return portCache[2].id;
         }
 
-        return Port::INVALID_PORT_ID;
+        return InvalidPortID;
     }
 
     // Clears the earliest entry of the cache and inserts a new port entry
@@ -388,7 +389,7 @@ class Bus : public MemObject
      *
      * @return a list of non-overlapping address ranges
      */
-    AddrRangeList getAddrRanges(Port::PortId id);
+    AddrRangeList getAddrRanges(PortID id);
 
     /**
      * Determine if the bus port is snooping or not.
@@ -397,7 +398,7 @@ class Bus : public MemObject
      *
      * @return a boolean indicating if this port is snooping or not
      */
-    bool isSnooping(Port::PortId id) const;
+    bool isSnooping(PortID id) const;
 
     /** Calculate the timing parameters for the packet.  Updates the
      * firstWordTime and finishTime fields of the packet object.
@@ -426,13 +427,13 @@ class Bus : public MemObject
      * @param id id of the busport that made the request
      * @return the max of all the sizes
      */
-    unsigned findBlockSize(Port::PortId id);
+    unsigned findBlockSize(PortID id);
 
     // event used to schedule a release of the bus
     EventWrapper<Bus, &Bus::releaseBus> busIdleEvent;
 
     bool inRetry;
-    std::set<Port::PortId> inRecvRangeChange;
+    std::set<PortID> inRecvRangeChange;
 
     /** The master and slave ports of the bus */
     std::vector<SlavePort*> slavePorts;
@@ -465,7 +466,7 @@ class Bus : public MemObject
     }
 
     /** Port that handles requests that don't match any of the interfaces.*/
-    short defaultPortId;
+    PortID defaultPortID;
 
     /** If true, use address range provided by default device.  Any
        address not handled by another port and not in default device's
diff --git a/src/mem/cache/cache_impl.hh b/src/mem/cache/cache_impl.hh
index d9e06c022..c7eb3f80b 100644
--- a/src/mem/cache/cache_impl.hh
+++ b/src/mem/cache/cache_impl.hh
@@ -352,7 +352,7 @@ Cache<TagStore>::access(PacketPtr pkt, BlkType *&blk,
 class ForwardResponseRecord : public Packet::SenderState, public FastAlloc
 {
     Packet::SenderState *prevSenderState;
-    Packet::NodeID prevSrc;
+    PortID prevSrc;
 #ifndef NDEBUG
     BaseCache *cache;
 #endif
@@ -1193,7 +1193,7 @@ Cache<TagStore>::handleSnoop(PacketPtr pkt, BlkType *blk,
                 pkt->assertShared();
             }
         } else {
-            Packet::NodeID origSrc = pkt->getSrc();
+            PortID origSrc = pkt->getSrc();
             cpuSidePort->sendAtomicSnoop(pkt);
             if (!alreadyResponded && pkt->memInhibitAsserted()) {
                 // cache-to-cache response from some upper cache:
diff --git a/src/mem/packet.hh b/src/mem/packet.hh
index 50a6f3d5a..8e3ef9456 100644
--- a/src/mem/packet.hh
+++ b/src/mem/packet.hh
@@ -41,6 +41,7 @@
  * Authors: Ron Dreslinski
  *          Steve Reinhardt
  *          Ali Saidi
+ *          Andreas Hansson
  */
 
 /**
@@ -231,7 +232,6 @@ class Packet : public FastAlloc, public Printable
   public:
     typedef uint32_t FlagsType;
     typedef ::Flags<FlagsType> Flags;
-    typedef short NodeID;
 
   private:
     static const FlagsType PUBLIC_FLAGS           = 0x00000000;
@@ -250,9 +250,6 @@ class Packet : public FastAlloc, public Printable
     /// Are the 'addr' and 'size' fields valid?
     static const FlagsType VALID_ADDR             = 0x00000100;
     static const FlagsType VALID_SIZE             = 0x00000200;
-    /// Is the 'src' field valid? 
-    static const FlagsType VALID_SRC              = 0x00000400;
-    static const FlagsType VALID_DST              = 0x00000800;
     /// Is the data pointer set to a value that shouldn't be freed
     /// when the packet is destroyed?
     static const FlagsType STATIC_DATA            = 0x00001000;
@@ -306,7 +303,7 @@ class Packet : public FastAlloc, public Printable
      * for example by using an appropriate sender state. The latter is
      * done in the cache and bridge.
      */
-    NodeID src;
+    PortID src;
 
     /**
      * Destination port identifier that is present on all response
@@ -316,7 +313,7 @@ class Packet : public FastAlloc, public Printable
      * response, and the destination is used, e.g. by the bus, to
      * select the appropriate path through the interconnect.
      */
-    NodeID dest;
+    PortID dest;
 
     /**
      * The original value of the command field.  Only valid when the
@@ -487,21 +484,21 @@ class Packet : public FastAlloc, public Printable
     bool hadBadAddress() const { return cmd == MemCmd::BadAddressError; }
     void copyError(Packet *pkt) { assert(pkt->isError()); cmd = pkt->cmd; }
 
-    bool isSrcValid() { return flags.isSet(VALID_SRC); }
+    bool isSrcValid() const { return src != InvalidPortID; }
     /// Accessor function to get the source index of the packet.
-    NodeID getSrc() const    { assert(flags.isSet(VALID_SRC)); return src; }
+    PortID getSrc() const { assert(isSrcValid()); return src; }
     /// Accessor function to set the source index of the packet.
-    void setSrc(NodeID _src) { src = _src; flags.set(VALID_SRC); }
+    void setSrc(PortID _src) { src = _src; }
     /// Reset source field, e.g. to retransmit packet on different bus.
-    void clearSrc() { flags.clear(VALID_SRC); }
+    void clearSrc() { src = InvalidPortID; }
 
-    bool isDestValid() { return flags.isSet(VALID_DST); }
+    bool isDestValid() const { return dest != InvalidPortID; }
     /// Accessor function for the destination index of the packet.
-    NodeID getDest() const     { assert(flags.isSet(VALID_DST)); return dest; }
+    PortID getDest() const { assert(isDestValid()); return dest; }
     /// Accessor function to set the destination index of the packet.
-    void setDest(NodeID _dest) { dest = _dest; flags.set(VALID_DST); }
+    void setDest(PortID _dest) { dest = _dest; }
     /// Reset destination field, e.g. to turn a response into a request again.
-    void clearDest() { flags.clear(VALID_DST); }
+    void clearDest() { dest = InvalidPortID; }
 
     Addr getAddr() const { assert(flags.isSet(VALID_ADDR)); return addr; }
     unsigned getSize() const  { assert(flags.isSet(VALID_SIZE)); return size; }
@@ -538,6 +535,7 @@ class Packet : public FastAlloc, public Printable
      */
     Packet(Request *_req, MemCmd _cmd)
         :  cmd(_cmd), req(_req), data(NULL),
+           src(InvalidPortID), dest(InvalidPortID),
            bytesValidStart(0), bytesValidEnd(0),
            time(curTick()), senderState(NULL)
     {
@@ -558,6 +556,7 @@ class Packet : public FastAlloc, public Printable
      */
     Packet(Request *_req, MemCmd _cmd, int _blkSize)
         :  cmd(_cmd), req(_req), data(NULL),
+           src(InvalidPortID), dest(InvalidPortID),
            bytesValidStart(0), bytesValidEnd(0),
            time(curTick()), senderState(NULL)
     {
@@ -586,7 +585,7 @@ class Packet : public FastAlloc, public Printable
         if (!clearFlags)
             flags.set(pkt->flags & COPY_FLAGS);
 
-        flags.set(pkt->flags & (VALID_ADDR|VALID_SIZE|VALID_SRC|VALID_DST));
+        flags.set(pkt->flags & (VALID_ADDR|VALID_SIZE));
         flags.set(pkt->flags & STATIC_DATA);
 
     }
@@ -644,8 +643,7 @@ class Packet : public FastAlloc, public Printable
         flags.clear(EXPRESS_SNOOP);
 
         dest = src;
-        flags.set(VALID_DST, flags.isSet(VALID_SRC));
-        flags.clear(VALID_SRC);
+        clearSrc();
     }
 
     void
diff --git a/src/mem/port.cc b/src/mem/port.cc
index 9cebd5897..554f5bb1e 100644
--- a/src/mem/port.cc
+++ b/src/mem/port.cc
@@ -50,7 +50,7 @@
 #include "mem/mem_object.hh"
 #include "mem/port.hh"
 
-Port::Port(const std::string &_name, MemObject& _owner, PortId _id)
+Port::Port(const std::string &_name, MemObject& _owner, PortID _id)
     : portName(_name), id(_id), peer(NULL), owner(_owner)
 {
 }
@@ -62,7 +62,7 @@ Port::~Port()
 /**
  * Master port
  */
-MasterPort::MasterPort(const std::string& name, MemObject* owner, PortId _id)
+MasterPort::MasterPort(const std::string& name, MemObject* owner, PortID _id)
     : Port(name, *owner, _id), _slavePort(NULL)
 {
 }
@@ -146,7 +146,7 @@ MasterPort::printAddr(Addr a)
 /**
  * Slave port
  */
-SlavePort::SlavePort(const std::string& name, MemObject* owner, PortId id)
+SlavePort::SlavePort(const std::string& name, MemObject* owner, PortID id)
     : Port(name, *owner, id), _masterPort(NULL)
 {
 }
diff --git a/src/mem/port.hh b/src/mem/port.hh
index 840952354..c70733bf6 100644
--- a/src/mem/port.hh
+++ b/src/mem/port.hh
@@ -78,14 +78,6 @@ class MemObject;
 class Port
 {
 
-  public:
-
-    /** A type name for the port identifier. */
-    typedef int PortId;
-
-    /** A symbolic name for the absence of a port id. */
-    static const PortId INVALID_PORT_ID = -1;
-
   private:
 
     /** Descriptive name (for DPRINTF output) */
@@ -95,9 +87,9 @@ class Port
 
     /**
      * A numeric identifier to distinguish ports in a vector, and set
-     * to INVALID_PORT_ID in case this port is not part of a vector.
+     * to InvalidPortID in case this port is not part of a vector.
      */
-    const PortId id;
+    const PortID id;
 
     /** A pointer to the peer port.  */
     Port* peer;
@@ -112,7 +104,7 @@ class Port
      * @param _owner The MemObject that is the structural owner of this port
      * @param _id A port identifier for vector ports
      */
-    Port(const std::string& _name, MemObject& _owner, PortId _id);
+    Port(const std::string& _name, MemObject& _owner, PortID _id);
 
     /**
      * Virtual destructor due to inheritance.
@@ -125,7 +117,7 @@ class Port
     const std::string name() const { return portName; }
 
     /** Get the port id. */
-    PortId getId() const { return id; }
+    PortID getId() const { return id; }
 
   protected:
 
@@ -167,7 +159,7 @@ class MasterPort : public Port
   public:
 
     MasterPort(const std::string& name, MemObject* owner,
-               PortId id = INVALID_PORT_ID);
+               PortID id = InvalidPortID);
     virtual ~MasterPort();
 
     void bind(SlavePort& slave_port);
@@ -305,7 +297,7 @@ class SlavePort : public Port
   public:
 
     SlavePort(const std::string& name, MemObject* owner,
-              PortId id = INVALID_PORT_ID);
+              PortID id = InvalidPortID);
     virtual ~SlavePort();
 
     void bind(MasterPort& master_port);