diff --git a/src/main/scala/diplomacy/Nodes.scala b/src/main/scala/diplomacy/Nodes.scala
index b1a46e69..db6b3513 100644
--- a/src/main/scala/diplomacy/Nodes.scala
+++ b/src/main/scala/diplomacy/Nodes.scala
@@ -14,20 +14,26 @@ trait InwardNodeImp[DI, UI, EI, BI <: Data]
 {
   def edgeI(pd: DI, pu: UI): EI
   def bundleI(ei: Seq[EI]): Vec[BI]
-  def mixI(pu: UI, node: InwardNode[DI, UI, BI]): UI = pu
   def colour: String
   def connect(bo: => BI, bi: => BI, e: => EI)(implicit sourceInfo: SourceInfo): (Option[LazyModule], () => Unit)
+
+  // optional methods to track node graph
+  def mixI(pu: UI, node: InwardNode[DI, UI, BI]): UI = pu // insert node into parameters
+  def getO(pu: UI): Option[BaseNode] = None // most-outward common node
 }
 
-// DO = Downwards flowing Parameters generated by the outner side of the node
-// UO = Upwards   flowing Parameters received on the outner side of the node
+// DO = Downwards flowing Parameters generated by the outer side of the node
+// UO = Upwards   flowing Parameters received on the outer side of the node
 // EO = Edge Parameters describing a connection on the outer side of the node
 // BO = Bundle type used when connecting to the outer side of the node
 trait OutwardNodeImp[DO, UO, EO, BO <: Data]
 {
   def edgeO(pd: DO, pu: UO): EO
   def bundleO(eo: Seq[EO]): Vec[BO]
-  def mixO(pd: DO, node: OutwardNode[DO, UO, BO]): DO = pd
+
+  // optional methods to track node graph
+  def mixO(pd: DO, node: OutwardNode[DO, UO, BO]): DO = pd // insert node into parameters
+  def getI(pd: DO): Option[BaseNode] = None // most-inward common node
 }
 
 abstract class NodeImp[D, U, EO, EI, B <: Data]
@@ -46,6 +52,8 @@ abstract class BaseNode
   def name = lazyModule.name + "." + nodename
   def omitGraphML = outputs.isEmpty && inputs.isEmpty
 
+  protected[diplomacy] def gci: Option[BaseNode] // greatest common inner
+  protected[diplomacy] def gco: Option[BaseNode] // greatest common outer
   protected[diplomacy] def outputs: Seq[BaseNode]
   protected[diplomacy] def inputs:  Seq[BaseNode]
   protected[diplomacy] def colour:  String
@@ -147,6 +155,9 @@ class MixedNode[DI, UI, EI, BI <: Data, DO, UO, EO, BO <: Data](
     i.map(inner.mixI(_, this))
   }
 
+  protected[diplomacy] def gco = if (iParams.size != 1) None else inner.getO(iParams(0))
+  protected[diplomacy] def gci = if (oParams.size != 1) None else outer.getI(oParams(0))
+
   lazy val edgesOut = (oPorts zip oParams).map { case ((i, n), o) => outer.edgeO(o, n.iParams(i)) }
   lazy val edgesIn  = (iPorts zip iParams).map { case ((o, n), i) => inner.edgeI(n.oParams(o), i) }
 
diff --git a/src/main/scala/uncore/tilelink2/Nodes.scala b/src/main/scala/uncore/tilelink2/Nodes.scala
index 56a8ec66..24668401 100644
--- a/src/main/scala/uncore/tilelink2/Nodes.scala
+++ b/src/main/scala/uncore/tilelink2/Nodes.scala
@@ -72,9 +72,21 @@ object TLImp extends NodeImp[TLClientPortParameters, TLManagerPortParameters, TL
   }
 
   override def mixO(pd: TLClientPortParameters, node: OutwardNode[TLClientPortParameters, TLManagerPortParameters, TLBundle]): TLClientPortParameters  =
-   pd.copy(clients  = pd.clients.map  { c => c.copy (nodePath = node +: c.nodePath) })
+    pd.copy(clients  = pd.clients.map  { c => c.copy (nodePath = node +: c.nodePath) })
   override def mixI(pu: TLManagerPortParameters, node: InwardNode[TLClientPortParameters, TLManagerPortParameters, TLBundle]): TLManagerPortParameters =
-   pu.copy(managers = pu.managers.map { m => m.copy (nodePath = node +: m.nodePath) })
+    pu.copy(managers = pu.managers.map { m => m.copy (nodePath = node +: m.nodePath) })
+  override def getO(pu: TLManagerPortParameters): Option[BaseNode] = {
+    val head = pu.managers.map(_.nodePath.headOption)
+    if (head.exists(!_.isDefined) || head.map(_.get).distinct.size != 1) {
+      None
+    } else {
+      val subproblem = pu.copy(managers = pu.managers.map(m => m.copy(nodePath = m.nodePath.tail)))
+      getO(subproblem) match {
+        case Some(x) => Some(x)
+        case None => Some(head(0).get)
+      }
+    }
+  }
 }
 
 case class TLIdentityNode() extends IdentityNode(TLImp)