L2VPN/L2transport, Cumulus Linux & hardware suggestion

Wed Jul 8 11:21:24 UTC 2020

On 8/Jul/20 12:42, Radu-Adrian Feurdean wrote:
> Errr.... sorry, but at the latest news, TCP was supposed to handle out of order packets and reorder them before sending them to upper layer.
> Not to mention hashing that almost systematically makes that all packets of the same TCP stream will be sent on the same link in an LAG (also on most if not all ECMP implementations). 

True, but TCP is unaware about if the interface is a LAG or a native
port. It's just another tube.

We tested per-packet load balancing on the MX Trio line cards. The
traffic spread is perfect, but the OoO experience is atrocious.

Either settle for per-flow load balancing, move to a faster native port,
or stick with ECMP at the IP layer.

For instance, this is why we don't do LACP for backbones anymore. It is
far more reliable to have individual IP links, and let ECMP do its thing.

The only place we run LAG's in our network is 802.1Q trunks between
router and switch. But the moment those get to 4x 10Gbps, we go native
100Gbps (which has the added benefit of making per-service policing on
the router easier).

Mark.