This is generally not related to the switch at all. It's upstream egress to the Internet and the most common cause is buffer bloat. Traffic on a 10Gb link betwe

This is generally not related to the switch at all. It's upstream egress to the Internet and the most common cause is buffer bloat. Traffic on a 10Gb link between local hosts won't be impacted by a 100Mb connection going out to the Internet and also a 10Gb connection sending to a 100Mb connection won't either. TCP congestion control matches the speed of the sender and during an initial connection burst the switch will likely buffer for a short period of time (which is exactly why the buffer exists) and drains at line rate. This is normal and all during this TCP is signaling congestion / back off. However, if your egress router doesn't handle buffer bloat you can end up with poor connections leaving the network, but generally this isn't because of local Ethernet speed mismatch or related to the switch at all. And even in cheap switches (think Realtek / Broadcom chips in $30 switches) they have dynamic shared pools. An elephant flow can exhaust some of that pool, but even the cheap stuff won't allow a single port to exhaust all resources as claimed. 10Gb to 100Gb UDP? Sure... Maybe in this scenario you end up with some odd behavior, but this isn't going to be normal usage. We've got PAUSE frames, congestion control and hardware that's been doing this for decades. Even on the cheap switching. It is imperative to have a router, however that actually deals with buffer bloat appropriately and as your Internet pipe scales you want to be cognizant your router can handle queuing appropriately at those line rates. But ultimately... > A 10G host sending large data to a 100M peer will cause all packets between all other peers to drop once switch memory is filled up. ...is not true. Switches don't work like that.