How BGP Communities Help Hosting Providers Improve Traffic Engineering

Have you ever modified a network configuration and suddenly had an epiphany about the way the internet operates? This was my feeling when my co-worker explained that hosting providers rely heavily on BGP communities to manage traffic running over their networks. If you are curious how your VPS maintains speed in peak hours at the web-hosting provider you are using, this short guide should help you understand.

What Are BGP Communities?​

BGP communities are short labels that your hosting provider includes with BGP routes, enabling fellow networks to route traffic. Think of BGP communities as little notes containing messages for routers like, "Send this traffic here,""Do not take this path,""Take this link first and then connect to network X," and other verbiage indicating traffic flow.

I remember the first time I used BGP communities I thought it was funny and said, "This feels like cheat codes for the internet." Have you had that experience when you learned something really cool?

Why Do Hosting Providers USE BGP Communities?​

Hosting providers enjoy using these useful tags because they can manage and control traffic and process without doing a complete change to their entire routing methodology, ultimately saving time and reducing complications and "glitches" by doing it all at the same time.

How it helps:

• They gain greater control over route selections
• They can make latency quicker by choosing a faster path
• They are able to distribute traffic evenly, so no link may become overloaded
• They are able to send the traffic to nearby networks for better speed

When this is working well, you will notice your VPS seems quicker. I once watched a file transfer speed increase just because the provider used the right BGP community tag.

How BGP Communities Influence Traffic​

Have you ever wondered why your traffic sometimes prefers one ISP to another? BGP communities are mostly the reason for this. Service providers use them to move the traffic to the place they choose.

Common ways they use them:

• Prepending routes to make a specific path less preferred
• Sending traffic via a specific carrier
• Having your traffic avoid a network during a problem
• Helping improve global routing, so the user receives consistent speeds

Here are a few simple examples:

• NO_EXPORT - “Do not export this route outside your AS.”
• Local preference tags - “Take this faster path first.”
• Blackhole communities - “Drop traffic here because it is nasty.”

When you agree they are simple and so useful right?

Why This Matters for VPS Users​

This may sound highly technical, but it actually impacts you directly. When your VPS feels fast from one location and slow from another, it is probably because of a BGP community.

They help:

• Lower delay (latency)
• Keep the routing stable
• Avoid outages and more

In my experience I have seen a network completely flooded with attack traffic. The provider simply applied a blackhole community, and the bad traffic was simply gone in seconds.