updated the README file

diff --git a/planetlab/exp-tool/README b/planetlab/exp-tool/README
index 641aca2..d604e4d 100644 (file)
--- a/planetlab/exp-tool/README
+++ b/planetlab/exp-tool/README
@@ -2,14 +2,7 @@
 
 The Makefile contained in this directory can be used by an
 experimenter to dynamically create an overlay network in a PlanetLab
-slice, using the sliver-openvswitch distribution. At present, the
-Makefile only supports the creation of the basic topology (nodes and
-links). 
-All the additional configuration of the bridges/switches (in
-particular, connecting the switches to OpenFlow controllers or
-enabling the Spanning Tree Protocol aka STP) has to be done using the
-tools available in the Open vSwitch distribution. This may change in
-the future.
+slice, using the sliver-openvswitch distribution. 
 
 The overlay network supported by the Makefile may consist of:
 
@@ -45,13 +38,14 @@ On the experimenter box we need:
 - (optionally) the dot program from the graphviz distribution
 
 Then, we can simply copy the Makefile in a working directory on the
-experimenter box. The directory must also contain subdirectories 'L'
-and 'cache':
+experimenter box
 
 $ mkdir work
 $ cp /path/to/Makefile work
 $ cd work
-$ mkdir -p L cache
+$ mkdir init 
+
+The last command creates some subdirectories that are later used by the Makefile.
 
 
 * Example usage
@@ -65,7 +59,7 @@ contains four nodes:
 4) planetlab2.urv.cat
 
 
-Assume we have reserverd subnet 10.0.9.0/24 using vsys_net.  We are
+Assume we have reserved subnet 10.0.9.0/24 using vsys_net.  We are
 goint to build the following overlay network:
 
    10.0.9.1/24   10.0.9.2/24   10.0.9.3/24
@@ -111,8 +105,7 @@ the Open vSwitch servers, create the bridges and setup the tunnels. We
 can test that network is up by logging into a node and pinging some
 other node using the private subnet addresses:
 
-$ source conf.mk
-$ ssh -l $SLICE $HOST_1 ping 10.0.9.4
+$ ssh -l myslice onelab7.iet.unipi.it ping 10.0.9.4
 
 Links can be destroyed and created dynamically. Assume we now want the
 the topology to match the following one:
@@ -122,7 +115,7 @@ the topology to match the following one:
                      |
                      |
                       |
-                     4 ----------- 3 
+                      4 ----------- 3 
                  10.0.9.4/24  10.0.9.3/24
 
 
@@ -137,17 +130,18 @@ of the topology by typing:
 
 $ make graph.ps
 
-#### BEG WARNING xxx this feature is broken now that LINKS are defined in the same conf.mk file
-Or we can save the current state in the 'links' file (so that we can
-recreate it later):
+The current state of the nodes and links can be obtained by typing
+
+$ make snapshot > snapshot.mk
 
-$ ls L > links
-#### END WARNING xxx this feature is broken now that LINKS are defined in the same conf.mk file
+The snapshot.mk file follows the same format as conf.mk and can be used
+to recreate the topology at a later time:
 
+$ make CONF=snapshot.mk
 
 * Command reference
 
-All targets can be issued with the '-j' flag to (greatly) speed up operations.
+All targets can be issued with the '-j' flag to (greatly) speed up operations (*)
 It may also be useful to use the '-k' flag, so that errors on some nodes do not
 stop the setup on the other nodes.
 
@@ -167,3 +161,18 @@ del-bridge.N:      delete the bridge running on node HOST_N (this also tears down
 graph.ps       create a postscript file containing a (simple) graphical
                representation
                of the current topology
+
+====================================================
+
+(*) To get the greatest speedup from make -j you should also enable
+connection reuse in your ssh setup, e.g., by having the following lines
+in your .ssh/config:
+host *
+       ControlMaster auto
+       ControlPath ~/.ssh/ssh_mux_%h_%p_%r
+       ControlPersist 4h
+
+Please note, however, that maximum concurrent per-node reuse is usually
+set to something low (typically 10), and this is a problem if some node
+in your topology has many links. In this case you should raise that limit
+on the slivers, or limit makefile concurrency (e.g., by using make -j10).