How should you troubleshoot  WAN performance issues?  Your MPLS or VPLS network and your clients in field offices are complaining about slow WAN performance.  Your network should be performing better and you can’t figure out what the problem is.  You can contact SD-WAN-Experts to have their engineers solve your problem, but you want to try to solve the problems yourself.

1. The first thing to check seems trivial, but you need to confirm that the ports on your router and switch ports are configured for the same speed and duplex. Log into your switches and check the logs for mismatches of speed or duplex.  Auto-negotiation sometimes does not work properly, so a 10M port connected to a 100M port is mismatched.  Or you might have a half-duplex port connected to a full-duplex port.  Don’t assume that a 10/100/1000 port is auto-negotiating correctly!

2. Is your WAN performance problem consistent?  Does it occur at roughly the same time of day?  Or is it completely random? If you don’t have the monitoring tools to measure this, you are at a big disadvantage in resolving the issues on your own.

3. Do you have Class of Service configured on your WAN?   Do you have DSCP configured on your LAN?  What is the mapping of your DSCP values to CoS?

4. What kind of applications are traversing your WAN?  Are there specific apps that work better than others?

5. Have your reviewed bandwidth utilization on your carrier’s web portal to determine if you are saturating the MPLS port of any locations?  Even brief peaks will be enough to generate complaints.  Large files, such as CAD drawings, can completely saturate a WAN link.

6. Are you backing up or synchronizing data over the WAN?  Have you confirmed 100% that this work is completed before the workday begins?

7. Might your routing be taking multiple paths and not the most direct path?  Look at your routing tables.

8 . Next, you want to see long term trend statistics.  This means monitoring the SNMP streams from all your routers, using tools such as MRTG, NTOP or Cacti.  A two-week sampling should provide a very good picture of what is happening on your network to help troubleshoot your WAN.

NTOP allows you to

  • Sort network traffic according to many protocols
  • Show network traffic sorted according to various criteria
  • Display traffic statistics
  • Store on disk persistent traffic statistics in RRD format
  • Identify the identity (e.g. email address) of computer users
  • Passively (i.e. without sending probe packets) identify the host OS
  • Show IP traffic distribution among the various protocols
  • Analyse IP traffic and sort it according to the source/destination
  • Display IP Traffic Subnet matrix (who’s talking to who?)
  • Report IP protocol usage sorted by protocol type
  • Act as a NetFlow/sFlow collector for flows generated by routers (e.g. Cisco and Juniper) or switches (e.g. Foundry Networks)
  • Produce RMON-like network traffic statistic

MRTG (Multi-Router Traffic Grapher) provides easy to understand graphs of your network bandwidth utilization.

MRTG Picture

Cacti requires a MySQL database.  It is a complete network graphing solution designed to harness the power of RRDTool‘s data storage and graphing functionality. Cacti provides a fast poller, advanced graph templating, multiple data acquisition methods, and user management features out of the box. All of this is wrapped in an intuitive, easy to use interface that makes sense for LAN-sized installations up to complex networks with hundreds of devices.

Both NTOP and MRTG are freeware applications to help troubleshoot your WAN that will run on the freeware versions of Linux.  As a result, they can be installed on almost any desktop computer that has outlived its value as a Windows desktop machine.  If you are skilled with Linux and networking, and you have the time, you can install this monitoring system on your own. You will need to get your carrier to provide read-only access to your router SNMP traffic.

But you might find it more cost-effective to have the engineers at SD-WAN-Experts do the work for you.  All you need to do is provide an available machine with a Linux install (Ubuntu, CentOS, RedHat, etc) with remote access via a VPN.  Our engineers will then download all the software remotely, install and configure the machine.  When we are done with the monitoring, besides understanding how to solve your problem (and solving it!) you will have your own network monitoring system installed for your use on a daily basis.  We’ll teach you how to use it, which is quite simple using the web-based tools, so you can view it from any machine on your network.

If you need assistance in troubleshooting your wide area network, contact SD-WAN-Experts today!

You might also find these troubleshooting tips of interest;

Troubleshooting MPLS Network Performance Issues

Packet Loss and How It Affects Performance

Troubleshooting VPLS and Ethernet Tunnels over MPLS