few big monolithic PEs vs many small PEs

Fri Jun 21 08:06:49 UTC 2019

On 21/Jun/19 09:36, adamv0025 at netconsultings.com wrote:

> And indeed there are cases where we connect customers directly on to
> the PEs, but then it's somehow ok for a line-card to be part of just a
> single chassis (or a PE). 

We'd typically do this for very high-speed ports (100Gbps), as it's
cheaper to aggregate 10Gbps-and-slower via an Ethernet switch trunking
to a router line card.

> Now let's take a step even further what if the line-card is not inside the chassis anymore -cause it's a fabric-extender or a satellite card.
> Why all of a sudden we'd be uncomfortable again to have it part of just a single chassis (and there are tons of satellite/extender topologies to prove that this is a real concern among operators).

I never quite saw the use-case for satellite ports. To me, it felt like
vendors trying to find ways to lock you into their revenue stream
forever, as many of these architectures do not play well with the other
kids. I'd rather keep it simple and have 802.1Q trunks between router
line cards and affordable Ethernet switches.

We are currently switching our Layer 2 aggregation ports in the data
centre from Juniper to Arista, talking to a Juniper edge router. I'd
have been in real trouble if I'd fallen for Juniper's satellite system,
as they have a number of shortfalls in the Layer 2 space, I feel.

> So to circle back to a standalone aggregation device -should we try and complicate the design by creating this "fabric" (PEs "spine" and aggregation devices "leaf") in an attempt to increase resiliency or shall we treat each aggregation device as unitary indivisible part of a single PE as if it was a card in a chassis -cause if the economics worked It would be a card in a chassis?

See my previous response to you.

Mark.