SEBA-958 send periodic port stats

Change-Id: I981e6c70b214845d87e8ae96b370fcdf58ccfef3
diff --git a/configs/bbsim.yaml b/configs/bbsim.yaml
index dcba903..23a6cc9 100644
--- a/configs/bbsim.yaml
+++ b/configs/bbsim.yaml
@@ -37,6 +37,7 @@
   reboot_delay: 10      # reboot delay in seconds
   # firmware_version: ""
   # device_id: 0a:0a:0a:0a:0a:<id>
+  port_stats_interval: 20 # in seconds
 
 # BBR settings
 bbr: