How African Internet Is Routed?

[dotcat]

Question is basically this. If someone in Mozambique or Angola tries to access a server based in South Africa. What route will the traffic take? Will it first be routed to Europe and then to South Africa or directly to South Africa?

In addition what are countries on the west coast of africa below the cable breaks doing now that the cables are broken - do they just not have internet?

Thanks.

 

[MirageF1]

Good q...

 

[Herr der Verboten]

Question is basically this. If someone in Mozambique or Angola tries to access a server based in South Africa. What route will the traffic take? Will it first be routed to Europe and then to South Africa or directly to South Africa?

In addition what are countries on the west coast of africa below the cable breaks doing now that the cables are broken - do they just not have internet?

Thanks.

 

[My_King]

Shortest path first

 

[dotcat]

Reason I ask is someone said it all goes to Europe first.

 

[My_King]

Reason I ask is someone said it all goes to Europe first.

OSPF detects changes in the topology, such as link failures, and converges on a new loop-free routing structure within seconds.

So I expect a no. But hey, what do I know

 

[Genisys]

Reason I ask is someone said it all goes to Europe first.

How long is a piece of string?

There is no simple answer. In the ideal world, it should route directly to South Africa, however, it doesn't mean that it always routes directly, depending on the setup the ISP is using it could also be routing via Asia or Australia, yet again, depends entirely on your ISP's decision on who it peers with and where they peer, and what routes are available to them to use.

 

[syntax]

OSPF detects changes in the topology, such as link failures, and converges on a new loop-free routing structure within seconds.

So I expect a no. But hey, what do I know

Although this isnt OSPF deciding this, the idea is right.
The question though really depends on what connectivity your provider has in that country.
If they peer and only peer with Europe, then traffic will go via them to europe and then use a provider there who has knowledge of your destination

Now days, most countries and providers make use of local internet exchange points (IXP's) to exchange routes locally either between providers or any companies with their own AS.

ISP's exchange routes and generally the bigger ones receive a full feed (which would contain all possible routes on the internet). From this they will have knowledge of where the next best hop to send the traffic to is. Now if they only get this info from Europe, then thats where your traffic goes. If they get a feed from another countries ISP in Africa, then thats where it goes.

 

[powermzii]

Although this isnt OSPF deciding this, the idea is right.
The question though really depends on what connectivity your provider has in that country.
If they peer and only peer with Europe, then traffic will go via them to europe and then use a provider there who has knowledge of your destination

Now days, most countries and providers make use of local internet exchange points (IXP's) to exchange routes locally either between providers or any companies with their own AS.

ISP's exchange routes and generally the bigger ones receive a full feed (which would contain all possible routes on the internet). From this they will have knowledge of where the next best hop to send the traffic to is. Now if they only get this info from Europe, then thats where your traffic goes. If they get a feed from another countries ISP in Africa, then thats where it goes.

To build on this - if one of their hops to Europe for example KNOWS of the SA server could they redirect the traffic at that point? e.g. before the packet goes all the way to Europe its redirected to SA in Rwanda for example?

 

[syntax]

To build on this - if one of their hops to Europe for example KNOWS of the SA server could they redirect the traffic at that point? e.g. before the packet goes all the way to Europe its redirected to SA in Rwanda for example?

Absolutely, each hop makes their own decision about how to get to the destination based on the information they have.
The source router doesnt make a decision to send it to europe, it makes a decision to send it to the best next hop. It wants to get to SA, and its been told that the best route to get there is hop X. If its best next hop is Europe to get to SA, it means that there is likely a direct connection (or pseudo connection) to Europe and no other better connections advertising an SA route.

If there are 10 hops in the chain on source routers link A and 15 hops on source routers link B, then the source router will send it out link A to its next hop. That next hop will have to make the same decisions and see which link to send it out.

It can get complicated because that next hop might not have shared all its routes or it might have filtering etc, which is why its path may be different to the source router, and instead of the expected 9 hops left that the source router would have seen, it could be more or less. This filtering and traffic manipulation could happen for a variety of reasons

 

[powermzii]

Absolutely, each hop makes their own decision about how to get to the destination based on the information they have.
The source router doesnt make a decision to send it to europe, it makes a decision to send it to the best next hop. It wants to get to SA, and its been told that the best route to get there is hop X. If its best next hop is Europe to get to SA, it means that there is likely a direct connection (or pseudo connection) to Europe and no other better connections advertising an SA route.

If there are 10 hops in the chain on source routers link A and 15 hops on source routers link B, then the source router will send it out link A to its next hop. That next hop will have to make the same decisions and see which link to send it out.

It can get complicated because that next hop might not have shared all its routes or it might have filtering etc, which is why its path may be different to the source router, and instead of the expected 9 hops left that the source router would have seen, it could be more or less. This filtering and traffic manipulation could happen for a variety of reasons

Fantastic explanation - thank you. This post along with some in the CISP feedback thread about some games preferring Brazil vs Europe brings it all together, i.e. the theory and the practical. Thanks again

 

[yogidabear]

Sort of.. the first thing BGP not OSPF does is see if the hop can be resolved. So if the cable breaks those routes just dont exist, and the next ones come in to play. They are weighted, costed etc and cost does sometimes mean money but typically thats just a metric. Am sure this is just theoretical so if the OP says what happens now from Mozambique to an SA server, well nothing as the cable was not broken and it still has great access on Seacom as its east africa. Maybe I dont get the question?. Mozambique to London maybe?