[afnog] IP transit and Load Balancing

[Joey ESQUIBAL]

Hi Nishal,


> On Jun 9, 2015, at 5:45 PM, Nishal Goburdhan <nishal at controlfreak.co.za> wrote:
> 
> On 9 Jun 2015, at 18:25, Joey ESQUIBAL wrote:
> 
>> Dear AfNOG,
>> 
>> I trust this e-mail finds everyone well.
>> May I ask your opinion and or best practice about having multiple IP transit to 4 different IPLC's.
>> For argument’s sake, I have allocated sample capacities on each circuit below:
>> 
>> IPLC 1 (1 x STM4) => IP Transit 1
>> IPLC 2 (1 x STM4) => IP Transit 2
>> IPLC 3 (2 x STM1) => IP Transit 1
>> IPLC 4 (2 x STM1) => IP Transit 2
>> 
>> All circuit ends to different geographical locations.
>> 
>> I’m thinking of having two IP transit (which I think should be good already) and advertise specific prefix(es) on each peer.
> 
> hi joey,
> 
> in general having two transit providers is a good thing.  three is still ok, but more than that (ie. four and greater) becomes a nightmare to deal with, so, you’re already off to a good start, if you have just two;  no reason to change that!

Joey: In fact, I have two IP Transit now and I plan to maintain the same. I’m planning on having three but I think two should be more than enough already. So I think I'm in good shape.
> 
> the next part of multihoming deals with knowing when, and where, to advertise your subnets.  since these are in four separate locations that will make it a little more difficult.  one (medium term) suggestion i would make, is to figure out how to get them to, say, two locations.  being able to make consistent advertisements from centralised locations helps to make your network easier to manage as your grow.
> 
> immediately, you’ll want to announce your aggregate prefixes across all of these links.  then, a good strategy would be to chop up the aggregate into half (initially) and advertise these more specifics (as well as the aggregates) across the links you need to load - in this case, your STM-4 circuits.  you might then also need to chop up those again, to again, artificially create load.  that’s ok to do really.
> 
> the trick here is to remember that you _should_ advertise your aggregate out of all of the circuits (should there be some sort of failure).  and i would strongly advocate that you work towards centralising the two locations that you pull bandwidth into your network;  eg. a pop in LDN and/or AMS, or similar… because then you can manage this de-aggregation inside your network, and make more effective use of your bandwidth.

Joey: unfortunately, all of these circuits are ending in 4 different locations. But yes, I agree with you to centralise the two locations to make it easier to manage my bandwidth.

I’ll send you a ping tomorrow to explain the topology why we ended up with four different circuits.

—Joey

> 
> i’ve not gone into a lot of detail, since there’s a lot that can be written here.  feel free to ping me if you need more specifics.
> 
> —n.

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