Full vs partial transit - cost / explain !

reactive-uk · 11th January 2008

When buying connectivity for a number of racks, and with one eye on the budget (and potential price rises like power) i have been trying to understand the differing attributes of full and partial transit.

Am I right in thinking that partial transit is where a supplier (the upstream ISP) has made private arrangements to 'swap' traffic locally with a number of other ISPs / hosts / ADSL providers etc, and this traffic doesnt ever reach the Internet backbone (ie goes from my server to my chosen supplier who sends it off direct to xyz domestic adsl ISP). The higher the number of private interconnect deals my provider does, the higher their 'number' - any route not covered by a deal simply wont connect

Full transit is then 'proper' connectivity to the backbone via 'the big boys' - guaranteed to get there (ok well no actual guarantees!)

As an example (only!) one transit supplier is offering partial transit at under £2 a mbit in 100Mbit lumps, but full at £12 a Mbit (no names so im not accused of promoting etc!).

Presumably to get the best bang for the buck I buy some of each and either they (how?) or I (BGP4 router?) blend it all together. The ratio depends on how full their partial is, and my traffic profile?

Assuming we're talking CDRs of 100Mbit plus, would it be usual to buy in a mix like this, and generally do i run the router or would they as part of the deal?

Thanks once again to anyone who answers one of my never ending questions...!

CrystalVPS · 11th January 2008

Put simply, if you're unsure - you're best to go static routed, most people will do statically routed transit cheaper than BGP presented full transit.

you'd need to have an ASN, Your own PI/Similar space, Your own routers, Sufficient justification for the ASN/PI. If people are pushing X00mbit/s they'll usually do peering themselves.

Going BGP isn't the cheap way of doing it, negotiate with who is selling the racks and try to get a nice price on statically routed transit, it's the cheapest way of doing it

adamsmith · 11th January 2008

Yes, partial transit will consist of your provider's peering routes (often their own plus routes bought in from another tier 2). Since your upstream provider isn't paying transit rates they will often offer you the partial transit at very low cost.

You will need a BGP router and at least 1 full transit provider to take advantage of this unless you only want to be visible to half of the internet! As BGP will by default prefer the shortest path (in terms of AS hops), your partial feed will often be used over your more expensive full transit thus saving you a little money and (in theory) improving your network + latency to your users.

If you're asking these questions, you probably won't find this worth the hassle - there are plenty of companies out there who will sell you IP transit for peanuts if your usage is large enough to justify the above setup. Alternatively you could look for a consultant to help you set up your AS.

HTH, good luck

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JamesSykes · 11th January 2008

Partial is usually just peering traffic so it's generally free to the ISP. (not counting running costs of course)

Full traffic is just that and you will need at least some of this.

Some ISP's will sell you a mix of partial/full traffic. This can be quite nice if the partial transit is well connected and covers a large chunk of your demographic. (eg game-server traffic)

So instead of paying 10mbit at full rate you might pay 8mbit at partial rates and 2mbit for the full fat stuff.

administrator · 11th January 2008

If you don't know a lot about routing then go static.

Pick a decent large provider and you should get the cost down well well bellow £12 a mbit.

MK Hosting · 6th September 2008

This thread is 9 months old....