Dual Homed BGP

Sun Feb 16 16:08:12 UTC 2020

On Sun, Feb 16, 2020 at 12:45 PM Mark Tinka <mark.tinka at seacom.mu> wrote:

>
>
> On 25/Jan/20 02:49, Baldur Norddahl wrote:
>
> >
> >
> >
> > The solution is to stay clear of tier 1 networks. Find a good local
> > tier 3. Whatever you are going to do, they will do better.
>
> So all our transit comes from the top 7 "global" carriers. Yes,
> including Cogent :-).
>
> But that only accounts for about 15% of our overall traffic. The rest
> comes from peering.
>
> Mark.
>
>
>From the perspective of someone just starting out being dual homed, this
will be very different. You are not going to get 7 transits and you are not
going to be able to peer 85% of the traffic. That is why I advocate that it
is better to buy transit from a middle tier company. Instead of getting a
connection to just one so called global carrier, you get a package deal
with connection to all of them and 85% peering one step removed. Plus many
of the companies that the middle tier has a peering with, is something the
tier 1 companies would refuse to peer (exception Hurricane Electric).

Also while your company may not need dual connections to each transit, the
situation is completely different from the perspective of a small dual
homed customer of yours. That is a lot of paths that are lost if this
customer where to experience a disruption to the connection to your network.

This is especially true if there is an unbalance between the two chosen
transit providers. Say the other provider is Cogent, which are famous for
refusing to peer. That means that all those peers, unless they have a
Cogent contract, they will need to find an indirect path to replace your
peering.

Of course I may also recommend to simply set your expectations modestly.
Dual homing will get you redundancy but unless you line up all your ducks
correctly, you should expect some brownouts in the case of a link failure.
Simply tell the boss, that unless he wants to pay at least double in every
way, there will be expected downtime in the order of 5 minuttes in the case
of a link failure.

Regards,

Baldur
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