diff --git a/db/Experiment.pm.in b/db/Experiment.pm.in
index 1e9e2743d66cbb14b33fbbab4116453cad044434..d41c01d9979e028fcc98a680019d51419cc31ac8 100644
--- a/db/Experiment.pm.in
+++ b/db/Experiment.pm.in
@@ -99,6 +99,7 @@ my $EXPT_RESOURCESHOSED = 0;
 		   "virt_simnode_attributes",
 		   "virt_user_environment",
 		   "virt_parameters",
+		   "virt_paths",
 		   # vis_nodes is locked during update in prerender, so we
 		   # will get a consistent dataset when we backup.
 		   "vis_nodes",
diff --git a/db/VirtExperiment.pm.in b/db/VirtExperiment.pm.in
index 1e917276164c616b4f44dbe2167894902b0a8184..1fa8d511d40b23672cde8c2dcfeeb8a3de19b567 100644
--- a/db/VirtExperiment.pm.in
+++ b/db/VirtExperiment.pm.in
@@ -72,6 +72,7 @@ my $debug	      = 0;
      "elabinelab_attributes"	=> [ "role", "attrkey", "ordering" ],
      "virt_tiptunnels"		=> [ "host", "vnode" ],
      "virt_parameters"          => [ "name", "value" ],
+     "virt_paths"		=> [ "pathname", "segmentname"],
 );
 
 # 
@@ -1184,5 +1185,10 @@ use vars qw(@ISA);
 @ISA = "VirtExperiment::VirtTableRow";
 use VirtExperiment;
 
+package VirtExperiment::VirtTableRow::virt_paths;
+use vars qw(@ISA);
+@ISA = "VirtExperiment::VirtTableRow";
+use VirtExperiment;
+
 # _Always_ make sure that this 1 is at the end of the file...
 1;
diff --git a/db/xmlconvert.in b/db/xmlconvert.in
index 78e4754f58661b28ce75e9e583ca31872d4bdba1..7b7d2563aae5bd21a5f194ec55a566cebd5a643f 100644
--- a/db/xmlconvert.in
+++ b/db/xmlconvert.in
@@ -116,9 +116,12 @@ my %virtual_tables =
      "virt_tiptunnels"		=> { rows  => undef, 
 				     tag   => "tiptunnels",
 				     row   => "tiptunnel"},
-     "virt_parameters"           => { rows  => undef, 
-				      tag   => "parameters",
-				      row   => "parameter"},
+     "virt_parameters"          => { rows  => undef, 
+				     tag   => "parameters",
+				     row   => "parameter"},
+     "virt_paths"               => { rows  => undef,
+				     tag   => "path_members",
+				     row   => "path_member"},
      # This is a fake table. See below. If we add more, lets generalize.
      "external_sourcefiles"	=> { rows  => undef, 
 				     tag   => "nsfiles",
diff --git a/sql/database-create.sql b/sql/database-create.sql
index 213740530daa4d3b6b79e361562527a5a33e2f75..419d4d3fcba6e515d5fd5314da0cbcfb60b9cda0 100644
--- a/sql/database-create.sql
+++ b/sql/database-create.sql
@@ -3829,6 +3829,8 @@ CREATE TABLE `virt_lans` (
   `trace_db` tinyint(1) NOT NULL default '0',
   `fixed_iface` varchar(128) default '',
   `layer` tinyint(4) NOT NULL default '2',
+  `implemented_by_path` tinytext,
+  `implemented_by_link` tinytext,
   PRIMARY KEY  (`exptidx`,`vname`,`vnode`,`vport`),
   UNIQUE KEY `vport` (`pid`,`eid`,`vname`,`vnode`,`vport`),
   KEY `pid` (`pid`,`eid`,`vname`),
@@ -3932,6 +3934,25 @@ CREATE TABLE `virt_parameters` (
   UNIQUE KEY `pideid` (`pid`,`eid`,`name`)
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1;
 
+--
+-- Table structure for table `virt_paths`
+--
+
+DROP TABLE IF EXISTS `virt_paths`;
+CREATE TABLE `virt_paths` (
+  `pid` varchar(12) NOT NULL default '',
+  `eid` varchar(32) NOT NULL default '',
+  `exptidx` int(11) NOT NULL default '0',
+  `pathname` varchar(32) NOT NULL default '',
+  `segmentname` varchar(32) NOT NULL default '',
+  `segmentindex` tinyint(4) unsigned NOT NULL default '0',
+  `layer` tinyint(4) NOT NULL default '0',
+  PRIMARY KEY  (`exptidx`,`pathname`,`segmentname`),
+  UNIQUE KEY `segidx` (`exptidx`,`pathname`,`segmentindex`),
+  KEY `pid` (`pid`,`eid`,`pathname`),
+  KEY `pideid` (`pid`,`eid`,`pathname`,`segmentname`)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1;
+
 --
 -- Table structure for table `virt_programs`
 --
diff --git a/sql/database-fill.sql b/sql/database-fill.sql
index 0606ec7bb4a4fda4cd3c21e46f2eb92937f1a3ab..bd23d33f9575d11219b24b581741b866f706d52f 100644
--- a/sql/database-fill.sql
+++ b/sql/database-fill.sql
@@ -691,7 +691,7 @@ REPLACE INTO table_regex VALUES ('virt_node_desires','desire','text','regex','^[
 REPLACE INTO table_regex VALUES ('virt_node_desires','weight','int','redirect','default:float',0,0,NULL);
 REPLACE INTO table_regex VALUES ('virt_nodes','pid','text','redirect','projects:pid',0,0,NULL);
 REPLACE INTO table_regex VALUES ('virt_nodes','eid','text','redirect','experiments:eid',0,0,NULL);
-REPLACE INTO table_regex VALUES ('virt_nodes','ips','text','regex','^(\\d{1,2}:\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3} {0,1})*$',0,1024,NULL);
+REPLACE INTO table_regex VALUES ('virt_nodes','ips','text','regex','^(\\d{1,2}:\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3} {0,1})*$',0,2048,NULL);
 REPLACE INTO table_regex VALUES ('virt_nodes','osname','text','redirect','os_info:osname',0,0,NULL);
 REPLACE INTO table_regex VALUES ('virt_nodes','cmd_line','text','redirect','default:tinytext',0,0,NULL);
 REPLACE INTO table_regex VALUES ('virt_nodes','rpms','text','regex','^([-\\w\\.\\/\\+:~]+;{0,1})*$',0,4096,NULL);
@@ -970,6 +970,14 @@ REPLACE INTO table_regex VALUES ('user_pubkeys','verify','text','redirect','defa
 REPLACE INTO table_regex VALUES ('user_pubkeys','user','text','redirect','users:uid',0,0,NULL);
 REPLACE INTO table_regex VALUES ('user_pubkeys','keyfile','text','regex','^[-_\\w\\.\\/:+]*$',1,256,NULL);
 
+REPLACE INTO table_regex VALUES ('virt_paths','pathname','text','redirect','virt_nodes:vname',0,0,NULL);
+REPLACE INTO table_regex VALUES ('virt_paths','segmentname','text','redirect','virt_nodes:vname',0,0,NULL);
+REPLACE INTO table_regex VALUES ('virt_paths','segmentindex','int','redirect','default:tinyuint',0,0,NULL);
+REPLACE INTO table_regex VALUES ('virt_paths','layer','int','redirect','default:tinyint',0,0,NULL);
+
+REPLACE INTO table_regex VALUES ('virt_lans','implemented_by_path','text','redirect','virt_paths:pathname',1,128,NULL);
+REPLACE INTO table_regex VALUES ('virt_lans','implemented_by_link','text','redirect','default:tinytext',0,0,NULL);
+
 REPLACE INTO table_regex VALUES ('elabinelab_attributes','role','text','regex','^(boss|router|ops|fs|node)$',0,0,NULL);
 REPLACE INTO table_regex VALUES ('elabinelab_attributes','attrkey','text','regex','^[-\\w\\.]+$',1,32,NULL);
 REPLACE INTO table_regex VALUES ('elabinelab_attributes','attrvalue','text','regex','^[-\\w\\.\\+,\\s\\/]+$',0,255,NULL);
diff --git a/sql/updates/4/210 b/sql/updates/4/210
new file mode 100644
index 0000000000000000000000000000000000000000..ae88d571582cd4b419f8c1df04e632b38b19b037
--- /dev/null
+++ b/sql/updates/4/210
@@ -0,0 +1,63 @@
+#
+# Add virt_paths
+#
+use strict;
+use libdb;
+
+sub DoUpdate($$$)
+{
+    my ($dbhandle, $dbname, $version) = @_;
+
+    if (!DBTableExists("virt_paths")) {
+	DBQueryFatal("CREATE TABLE `virt_paths` ( ".
+	     " `pid` varchar(12) NOT NULL default '', ".
+	     " `eid` varchar(32) NOT NULL default '', ".
+	     " `exptidx` int(11) NOT NULL default '0', ".
+	     " `pathname` varchar(32) NOT NULL default '', ".
+	     " `segmentname` varchar(32) NOT NULL default '', ".
+	     " `segmentindex` tinyint(4) unsigned NOT NULL default '0', ".
+	     " `layer` tinyint(4) NOT NULL default '0', ".
+	     " PRIMARY KEY  (`exptidx`,`pathname`,`segmentname`), ".
+	     " UNIQUE KEY `segidx` (`exptidx`,`pathname`,`segmentindex`), ".
+	     " KEY `pid` (`pid`,`eid`,`pathname`), ".
+             " KEY `pideid` (`pid`,`eid`,`pathname`,`segmentname`) ".
+	     ") ENGINE=MyISAM DEFAULT CHARSET=latin1");
+    }
+    DBQueryFatal("REPLACE INTO table_regex VALUES" . 
+		 " ('virt_paths', 'pathname', 'text', 'redirect', ".
+		 "  'virt_nodes:vname', 0,0,NULL)");
+    DBQueryFatal("REPLACE INTO table_regex VALUES" . 
+		 " ('virt_paths', 'segmentname', 'text', 'redirect', ".
+		 "  'virt_nodes:vname', 0,0,NULL)");
+    DBQueryFatal("REPLACE INTO table_regex VALUES" . 
+		 " ('virt_paths', 'segmentindex', 'int', 'redirect', ".
+		 "  'default:tinyuint', 0,0,NULL)");
+    DBQueryFatal("REPLACE INTO table_regex VALUES" . 
+		 " ('virt_paths', 'layer', 'int', 'redirect', ".
+		 "  'default:tinyint', 0,0,NULL)");
+ 
+    if (!DBSlotExists("virt_lans", "implemented_by_path")) {
+        DBQueryFatal("ALTER TABLE virt_lans ADD ".
+		     " `implemented_by_path` tinytext");
+    }
+    if (!DBSlotExists("virt_lans", "implemented_by_link")) {
+        DBQueryFatal("ALTER TABLE virt_lans ADD ".
+		     " `implemented_by_link` tinytext");
+    }
+
+    DBQueryFatal("REPLACE INTO table_regex VALUES" . 
+		 " ('virt_lans', 'implemented_by_path', 'text', 'redirect', ".
+		 "  'virt_paths:pathname', 1,128,NULL)");
+    DBQueryFatal("REPLACE INTO table_regex VALUES" . 
+		 " ('virt_lans', 'implemented_by_link', 'text', 'redirect', ".
+		 "  'default:tinytext', 0,0,NULL)");
+
+    # Unrelated bug fix.
+    DBQueryFatal("REPLACE INTO table_regex VALUES ".
+	 " ('virt_nodes','ips','text','regex', ".
+	 "  '^(\\d{1,2}:\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3} {0,1})*$',".
+	 "  0,2048,NULL");
+    
+    return 0;
+}
+1;
diff --git a/tbsetup/ns2ir/GNUmakefile.in b/tbsetup/ns2ir/GNUmakefile.in
index 8bcab0da99e086223fa660b9d417f186dda13155..9f6803a06a02fa63ccb41300209ee343301f9e62 100644
--- a/tbsetup/ns2ir/GNUmakefile.in
+++ b/tbsetup/ns2ir/GNUmakefile.in
@@ -1,6 +1,6 @@
 #
 # EMULAB-COPYRIGHT
-# Copyright (c) 2000-2006 University of Utah and the Flux Group.
+# Copyright (c) 2000-2010 University of Utah and the Flux Group.
 # All rights reserved.
 #
 
@@ -19,7 +19,7 @@ LIB_STUFF    = lanlink.tcl node.tcl sim.tcl tb_compat.tcl null.tcl \
 		  nsenode.tcl nstb_compat.tcl event.tcl firewall.tcl \
 		  elabinelab.ns elabinelab-withfsnode.ns \
 		  fw.ns timeline.tcl sequence.tcl \
-		  topography.tcl console.tcl
+		  topography.tcl console.tcl path.tcl
 BOSSLIBEXEC  = parse-ns
 USERLIBEXEC  = parse.proxy
 
diff --git a/tbsetup/ns2ir/lanlink.tcl b/tbsetup/ns2ir/lanlink.tcl
index 5229bdc3c9f26c7d1760157d072d601836eac804..566c296c5e06656974e9a4d862dcdeb48891c9b2 100644
--- a/tbsetup/ns2ir/lanlink.tcl
+++ b/tbsetup/ns2ir/lanlink.tcl
@@ -214,8 +214,9 @@ LanLink instproc init {s nodes bw d type} {
     # XXX Allow user to set the accesspoint.
     $self set accesspoint {}
 
-    # Optional layer
+    # Optional layer and implemented-by relationship
     $self set layer {}
+    $self set implemented_by {}
 
     # A simulated lanlink unless we find otherwise
     $self set simulated 1
@@ -324,6 +325,37 @@ Link instproc trace {{ttype "header"} {texpr ""}} {
     $fromqueue trace $ttype $texpr
 }
 
+#
+# A link can be implemented in terms of a path or
+# a link at a lower level of the stack.
+#
+Link instproc implemented_by {impl} {
+    $self instvar implemented_by
+    $self instvar layer
+    
+    if {[$impl info class] == "Path"} {
+	set implemented_by $impl
+    } elseif {[$impl info class] == "Link"} {
+	if {$layer == {}} {
+	    perror "\[$self implemented_by] no layer set!"
+	    return
+	}
+	set impl_layer [$impl set layer]
+	if {$impl_layer == {}} {
+	    perror "\[$self implemented_by] no layer set in $impl!"
+	    return
+	}
+	if {$impl_layer >= $layer} {
+	    perror "\[$self implemented_by] $impl is not at a lower layer!"
+	    return
+	}
+	set implemented_by $impl
+    } else {
+        perror "\[$self implemented_by] must be a link or a path!"
+        return
+    }
+}
+
 Lan instproc trace_snaplen {len} {
     $self instvar nodelist
     $self instvar linkq
@@ -720,6 +752,7 @@ Link instproc updatedb {DB} {
     $self instvar mustdelay
     $self instvar fixed_iface
     $self instvar layer
+    $self instvar implemented_by
 
     $sim spitxml_data "virt_lan_lans" [list "vname"] [list $self]
 
@@ -810,6 +843,13 @@ Link instproc updatedb {DB} {
 	if { $layer != {} } {
 	    lappend fields "layer"
 	}
+	if { $implemented_by != {} } {
+	    if {[$implemented_by info class] == "Path"} {
+		lappend fields "implemented_by_path"
+	    } else {
+		lappend fields "implemented_by_link"
+	    }
+	}
 
 	set values [list $self $nodeportraw $netmask $delay($nodeport) $rdelay($nodeport) $bandwidth($nodeport) $rbandwidth($nodeport) $backfill($nodeport) $rbackfill($nodeport)  $loss($nodeport) $rloss($nodeport) $cost($nodeport) $widearea $emulated $uselinkdelay $nobwshaping $encap $limit_  $maxthresh_ $thresh_ $q_weight_ $linterm_ ${queue-in-bytes_}  $bytes_ $mean_pktsize_ $wait_ $setbit_ $droptail_ $red_ $gentle_ $trivial_ok $protocol $node $port $ip $mustdelay]
 
@@ -839,6 +879,9 @@ Link instproc updatedb {DB} {
 	if { $layer != {} } {
 	    lappend values $layer
 	}
+	if { $implemented_by != {} } {
+	    lappend values $implemented_by
+	}
 
 	$sim spitxml_data "virt_lans" $fields $values
     }
diff --git a/tbsetup/ns2ir/nstb_compat.tcl b/tbsetup/ns2ir/nstb_compat.tcl
index 0bb2239d597d3e113c39d035a63c2e0f62d3bef6..1c157ecf1bb0e19c9a2a3902a36f127b68383cf4 100644
--- a/tbsetup/ns2ir/nstb_compat.tcl
+++ b/tbsetup/ns2ir/nstb_compat.tcl
@@ -261,6 +261,9 @@ Simulator instproc make-cloud {nodes bw delay args} {
     return [$self make-lan $nodes $bw $delay]
 }
 
+Simulator instproc make-path {linklist} {
+}
+
 Node instproc program-agent {args} {
 }
 
@@ -289,5 +292,8 @@ LanNode instproc trace {args} {
 LanNode instproc trace_endnode {args} {
 }
 
+LanNode instproc implemented_by {args} {
+}
+
 LanNode instproc unknown {m args} {
 }
diff --git a/tbsetup/ns2ir/parse.tcl.in b/tbsetup/ns2ir/parse.tcl.in
index eecb09aeaf32b1851e860fc2ec4a417d86a090cf..208ccf4ba2a2c21278bf39521639275ec8e71091 100644
--- a/tbsetup/ns2ir/parse.tcl.in
+++ b/tbsetup/ns2ir/parse.tcl.in
@@ -364,6 +364,7 @@ namespace eval GLOBALS {
 source ${GLOBALS::libdir}/nsobject.tcl
 source ${GLOBALS::libdir}/sim.tcl
 source ${GLOBALS::libdir}/lanlink.tcl
+source ${GLOBALS::libdir}/path.tcl
 source ${GLOBALS::libdir}/node.tcl
 source ${GLOBALS::libdir}/null.tcl
 source ${GLOBALS::libdir}/traffic.tcl
diff --git a/tbsetup/ns2ir/path.tcl b/tbsetup/ns2ir/path.tcl
new file mode 100644
index 0000000000000000000000000000000000000000..8801ccdc568af9a916025f69467f9c4bf535c561
--- /dev/null
+++ b/tbsetup/ns2ir/path.tcl
@@ -0,0 +1,50 @@
+# -*- tcl -*-
+#
+# EMULAB-COPYRIGHT
+# Copyright (c) 2000-2010 University of Utah and the Flux Group.
+# All rights reserved.
+#
+######################################################################
+# path.tcl
+#
+# A path is comprised of a set of links.
+######################################################################
+
+Class Path -superclass NSObject
+
+namespace eval GLOBALS {
+    set new_classes(Path) {}
+}
+
+Path instproc init {s links} {
+    # This is a list of the links
+    $self set mylinklist $links
+
+    # The simulator
+    $self set sim $s
+}
+
+Path instproc rename {old new} {
+    $self instvar sim
+    $self instvar mylinklist
+
+    $sim rename_path $old $new
+}
+
+Path instproc updatedb {DB} {
+    $self instvar mylinklist
+    var_import ::GLOBALS::pid
+    var_import ::GLOBALS::eid
+    $self instvar sim
+    
+    set idx 0
+
+    foreach link $mylinklist {
+	set fields [list "pathname" "segmentname" "segmentindex"]
+	set values [list $self $link $idx]
+
+	$sim spitxml_data "virt_paths" $fields $values	
+
+	incr idx
+    }
+}
diff --git a/tbsetup/ns2ir/sim.tcl.in b/tbsetup/ns2ir/sim.tcl.in
index 659bfbfcac2bc767a8930d8d7e884f189566890b..0fb0856b9cf27af035bd6cd39e99c6840813bfbe 100644
--- a/tbsetup/ns2ir/sim.tcl.in
+++ b/tbsetup/ns2ir/sim.tcl.in
@@ -47,6 +47,8 @@ Simulator instproc init {args} {
     array set lanlink_list {}
     $self instvar subnets;		# Indexed by IP subnet
     array set subnets {}
+    $self instvar path_list;		# Indexed by path id
+    array set path_list {}
 
     # link_map is indexed by <node1>:<node2> and contains the
     # id of the lanlink connecting them.  In the case of
@@ -271,6 +273,21 @@ Simulator instproc make-lan {nodelist bw delay args} {
     return $curlan
 }
 
+# make-path <linklist>
+Simulator instproc make-path {linklist args} {
+    var_import ::GLOBALS::last_class
+    $self instvar id_counter
+    $self instvar path_list
+
+    set curpath tbpath-path[incr id_counter]
+    
+    Path $curpath $self $linklist
+    set path_list($curpath) {}
+    set last_class $curpath
+    
+    return $curpath
+}
+
 Simulator instproc make-cloud {nodelist bw delay args} {
     $self instvar event_list
     $self instvar event_count
@@ -349,6 +366,7 @@ Simulator instproc event-group {{list {}}} {
 # method casues the 'ran' variable to be set to 1.
 Simulator instproc run {} {
     $self instvar lanlink_list
+    $self instvar path_list
     $self instvar node_list
     $self instvar event_list
     $self instvar prog_list
@@ -580,6 +598,9 @@ Simulator instproc run {} {
     foreach tg [array names topography_list] {
 	$tg updatedb "sql"
     }
+    foreach path [array names path_list] {
+	$path updatedb "sql"
+    }
 
     set fields [list "mem_usage" "cpu_usage" "forcelinkdelays" "uselinkdelays" "usewatunnels" "uselatestwadata" "wa_delay_solverweight" "wa_bw_solverweight" "wa_plr_solverweight" "encap_style" "allowfixnode"]
     set values [list $mem_usage $cpu_usage $forcelinkdelays $uselinkdelays $usewatunnels $uselatestwadata $wa_delay_solverweight $wa_bw_solverweight $wa_plr_solverweight $vlink_encapsulate $fix_current_resources]
@@ -954,6 +975,12 @@ Simulator instproc rename_topography {old new} {
     set topography_list($new) {}
 }
 
+Simulator instproc rename_path {old new} {
+    $self instvar path_list
+    unset path_list($old)
+    set path_list($new) {}
+}
+
 # find_link <node1> <node2>
 # This is just an accesor to the link_map datastructure.  If no
 # link is known between <node1> and <node2> the empty list is returned.