Thank you for that. Now, let me ask you this: so, let's say we are talking about that large datacenter with hundreds to thousands of servers. What are the possible reasons for why you would have multiple providers as opposed to just pumping everything through one?
Is it:
1) A provider might not have enough bandwidth available for your needs, so you need to diversify?
2) You would get multiple providers so that you try to reach as many destinations as possible directly? IOW, if I only have ATT, then in order to get to destination X that's on Level3 there's an extra hop wherever the hell ATT connects to Level3, and you also have Level3 yourself then the fastest route to that is through the Level3 network?
If you are large enough (say, you are a large national access or hosting provider), there is no single, even larger "The Internet, Inc." upstream provider you can use as your single link. You have to negotiate peering agreements with the other large actors so that you have reliable and affordable routes to all parts of the net. At this level you need things like BGP to know where to send traffic for a destination outside of your own net, because you could have several possible routes with different performance and/or price.
Unlike most LANs wich are either physically or logically (via the spanning tree protocol) structured like a tree, the core internet is a weighted graph.
1. Redundancy - although failures are rare, they do occur. So if one provider has a problem, traffic to all other points is not interrupted.
2. Pricing - you buy from multiple providers and thus are not locked in.
3. Latency - your customers want the lowest latency.
3a. Often times, companies will run an application in the data center and have remote offices connect over a VPN to the servers. Those remote offices will be in different geographic areas and will be using different local providers, all of which will have different network paths to reach you.
Peering - if you are large enough to provide say 100Mb/s or more of traffic continuously to one provider's network, they may choose to peer with you at little or no cost. This means that they give you the connection because the traffic is going to them directly and they don't have to maintain other high speed connections to some third party that they may have to pay. There is a lot of negotiation and at least 3 separate pricing strategies that each side can follow.
The simplest is "bill and keep" which is that each side provides no-cost access to the other's network, and they each bill their own customers and keep the proceeds.
Comments
Thank you for that. Now, let me ask you this: so, let's say we are talking about that large datacenter with hundreds to thousands of servers. What are the possible reasons for why you would have multiple providers as opposed to just pumping everything through one?
Is it:
1) A provider might not have enough bandwidth available for your needs, so you need to diversify?
2) You would get multiple providers so that you try to reach as many destinations as possible directly? IOW, if I only have ATT, then in order to get to destination X that's on Level3 there's an extra hop wherever the hell ATT connects to Level3, and you also have Level3 yourself then the fastest route to that is through the Level3 network?
3) All/None of the above/something else?
If you are large enough (say, you are a large national access or hosting provider), there is no single, even larger "The Internet, Inc." upstream provider you can use as your single link. You have to negotiate peering agreements with the other large actors so that you have reliable and affordable routes to all parts of the net. At this level you need things like BGP to know where to send traffic for a destination outside of your own net, because you could have several possible routes with different performance and/or price.
Unlike most LANs wich are either physically or logically (via the spanning tree protocol) structured like a tree, the core internet is a weighted graph.
1. Redundancy - although failures are rare, they do occur. So if one provider has a problem, traffic to all other points is not interrupted.
2. Pricing - you buy from multiple providers and thus are not locked in.
3. Latency - your customers want the lowest latency.
3a. Often times, companies will run an application in the data center and have remote offices connect over a VPN to the servers. Those remote offices will be in different geographic areas and will be using different local providers, all of which will have different network paths to reach you.
Peering - if you are large enough to provide say 100Mb/s or more of traffic continuously to one provider's network, they may choose to peer with you at little or no cost. This means that they give you the connection because the traffic is going to them directly and they don't have to maintain other high speed connections to some third party that they may have to pay. There is a lot of negotiation and at least 3 separate pricing strategies that each side can follow.
The simplest is "bill and keep" which is that each side provides no-cost access to the other's network, and they each bill their own customers and keep the proceeds.