This blog is meant to provide a simple overview of routing in general, for those new to networking, and as an addendum to my other two routing related blogs:

  1. Routing Tools Overview for Network Performance Monitor 10.5
  2. TROUBLESHOOTING WITH ROUTING TOOLS FOR NETWORK PERFORMANCE MONITOR 10.5

 

While network and internet routing can be quite complex, the fundamentals are easy to comprehend.

 

  • If I am at “Location A” and want to get to “Location Z” 
    • I might be able to take a direct route and get there without stopping. 
    • In other cases I might have to use an alternate route, going through “Location B” or “Location X” first along the way.

               01_locations.jpg

Let’s take a look at a simple network topology map and see what a route might look like connecting networks together from across the world.

 

  • Sender 1 - on the left side of the map - is connected to Router 1 (R1) in California.
  • Receiver 2 - on the right side of the map - is connected to Router 4 (R4) in Paris
  • Router 2 (R2)- in the middle of the map - is connected to both Router 1 and Router 4.

     01_routes.jpg

As you can see, if you want to send packets from Sender 1 to Receiver 2 there is only one route to take. Any device connected to Router 1 must go through Router 2 in order to get data to any other device connected to Router 4. In this scenario:

 

  • The “Origin” is Sender 1
  • The “Next Hop” is Router 2
  • And the “Destination” is Receiver 2

 

I am sure you can imagine other possible scenarios where additional Routers could serve as the “Next Hop” similar to Router 2 connecting Router 1 to Router 4. For example there might be a “Next Hop” Router in Miami in addition to New York, in which case you would have multiple pathways (routes) that could make connections between the Origin and Destination.

 

To summarize, there can be multiple routes that packets can take through networks to get to any given destination. With the new Routing tools now provided by SolarWinds NPM, you know have a view of end to end routing for easier troubleshooting of network issues.

 

Protocol Overview


A routing protocol defines how routers communicate with one another. Routers need to communicate with one another to share information that will enable them to select routes between any two network nodes. Routers can only communicate directly with their neighbors but information is passed along, one to another, so that eventually a router can gain and store an entire network topology. There are several different routing protocols in use today for both internal networks and external networks such as the internet. By “Internal” network we really mean an “Autonomous System” or “Autonomous Network” which is defined as a network that is under the domain and control of a single Administrative entity such as a corporate network.  Protocols for internal use are referred to as “interior” protocols while protocols used on the internet are referred to as… you guessed it, “exterior” protocols.

 

The SolarWinds routing resources and tools contained in Network Performance Monitor version 10.5 and above provides support for the following popular network protocols:

 

  • OSPF
  • RIP
  • BGP

 

These are important networking protocols that allow network traffic to traverse vast internal networks and span a wide array of self-contained but interconnected networks such as the internet. The first two, OSPF and RIP, are interior routing protocols otherwise known as “Interior Gateway Protocols” or IGP. IGPs share information within only one routing domain and cannot span across separate autonomous networks, the biggest impact of this limitation is that these protocols cannot be used on the internet. The third in the list is BGP or Border Gateway Protocol which is currently the most commonly used exterior gateway protocol and which allows all manner of autonomous networks to communicate across the internet.

 

To sum it up internal networks can use OSPF, RIP (or other IGP protocols) and if any of these internal networks need to communicate with other networks they can and most likely will use BGP to send packets across the internet.

Note: There are a few other protocols in use today such as EIGRP and we are working on integrating these into NPM for a future release. 

 

Now if only I could find a way to insert myself into a network packet, I could have lunch in Paris and be back to work in Austin for my 1pm meeting!