retry ssh commands to allow cell nodes to come up

Change-Id: I670befdc12f422ff97d86adf88ba97f156a21f77
diff --git a/tools/test/bin/onos-verify-cell b/tools/test/bin/onos-verify-cell
index 8999ad4..284a7c4 100755
--- a/tools/test/bin/onos-verify-cell
+++ b/tools/test/bin/onos-verify-cell
@@ -6,6 +6,18 @@
 [ ! -d "$ONOS_ROOT" ] && echo "ONOS_ROOT is not defined" >&2 && exit 1
 . $ONOS_ROOT/tools/build/envDefaults
 
+let err=0
+
 for node in $OCT $OCN $(env | sort | egrep "^OC[0-9]+" | cut -d= -f2); do
-    printf "%s: " $node; ssh -n -q -o StrictHostKeyChecking=no -o PasswordAuthentication=no $ONOS_USER@$node hostname
+    for i in 1 2 3 4 5 6; do
+        printf "%s: " $node; ssh -n -q -o StrictHostKeyChecking=no -o PasswordAuthentication=no -o ConnectTimeout=10 $ONOS_USER@$node hostname
+        if [ $? -eq 0 ]; then
+            let err=0
+            break
+        fi
+        let err=$?+$err
+    done
+    if [ $err -ne 0 ]; then
+        exit 1
+    fi
 done