What if you don’t run an ISP or a global internet backbone but you would still like to get some information on internet performance and routing to help build your case to move a customer from a service-provider MPLS network to an internet-based underlay with an overlay of SD-WAN? As it happens, there is one resource available to us all – Looking Glass Servers.

Many ISPs deploy Looking Glass Servers, which can be accessed through a standard browser and will give you information such as round-trip delay, routing preferences and actual routes taken from the Looking Glass Server location to your target IP address or domain.

You can find publicly available Looking Glass Servers here, with a list of over 1000 such servers, sorted by the network’s name on the internet – Autonomous System or AS number. Moreover, over here you will find a list sorted globally and regionally by ISP name.

Breaking it down: the steps & ping command

Anyone can access these “windows into the network” using a standard browser. You will need to enter the IP address or the domain name of your target destination. This could be an IP address in your data centre or a public internet service. Zscaler’s secure internet access nodes are a typical target for traffic from a branch site, so you would enter for instance the Zscaler London ZEN node (now called a ZIA Public Service Edge node), which is at “lon3-vpn.zscalertwo.net”. Then you would choose the location in the world that you wish to test from. We might recommend choosing a Looking Glass Server based in Amsterdam, as you may often find London as the back-up Public Service Edge node for branches in the Netherlands.

There are three things that you could typically look at. First of all, you can check the round-trip delay using the ping command. Normally, this is around 7 milliseconds (ms) between Amsterdam and London. You can also see the programmed routes and the preferred routing. Trying this on different ISPs can show those that are directly connected to Zscaler’s AS and those that go via an intermediary ISP backbone provider. And finally, you can see the actual routing taken by your packets at that time.

You typically get results from a series of 5 pings, but some ISPs enable you to do more. Thus, you can see how this latency varies so for the route above you would typically see round trip times of 5ms to 8ms – and of course run your queries at the time of day most important for your customers’ business to get a view of how internet time-of-day usage affects performance.

The round-trip times

You can also use the ping function to see typical round-trip times to your own servers from around the world. So, for example using BT Global Internet Connect service (AS5400) to a server in London you can see round-trip times of 2ms to 3ms in the UK, 17ms to 21ms from Brussels, 30ms from Madrid, 70ms from New York, 140ms from San Jose, 200ms from Hong Kong, rising to 275ms from Sydney.  You can also compare between providers, for example Sydney to London ranging from a best of 238ms to a slowest of 350ms. To put this into perspective, round trip delays over 250ms are noticeable on voice calls and for IP voice there will be plenty of added latency between the headset and the ISP’s server at both ends to add to the global hop.

Whilst the main purpose for ISPs for deploying Looking Glass Servers is to enable their own network operations teams to get an external view of how accurately their routing table changes have been deployed and how their network is performing for end-users, they are another useful source of information when it comes to planning a move from MPLS to internet and in choice of internet service provider.

Have a question? Get in touch!

Here at Brodynt we work with hundreds of internet service providers worldwide and can advise you further in how best to choose which ISPs to work with to enable you to meet the price and performance needs of your customers.

You are always welcome to drop us an e-mail to hello@brodynt.com and one of our Account Managers will be happy to assist you! Alternatively, engage in a discussion by leaving a comment below!