few big monolithic PEs vs many small PEs

Thu Jun 27 15:31:27 UTC 2019

On 27/Jun/19 14:48, James Bensley wrote:

> That to me is a simple scenario, and it can be mapped with a
> dependency tree. But in my experience, and maybe it's just me, things
> are usually a lot more complicated than this. The root cause is
> probably a bad design introducing too much complexity, which is
> another vote for smaller PEs from me. With more service dedicated PEs
> one can reduce or remove the possibility of piling multiple services
> and more complexity onto the same PE(s).

Which is one of the reasons we - painfully to the bean counters - insist
that routers are deployed for function.

We won't run peering and transit services on the same router.

We won't run SP and Enterprise on the same router as Broadband.

We won't run supporting services (DNS, RADIUS, WWW, FTP, Portals, NMS,
e.t.c.) on the same router where we terminate customers.

This level of distribution, although quite costly initially, means you
reduce the inter-dependency of services at a hardware level, and can
safely keep things apart so that when bits fail, you aren't committing
other services to the same fate.

Mark.