Performance Limitations of Virtual Switches in a VSX Environment

[HeikoAnkenbrand]

I’ve noticed that in a VSX environment the virtual switches don’t seem to achieve very high packet throughput.
In practice, I can’t get more than around 4–5 Gbps over a wrp interface. When I connect the same setup using physical switches + 100Gbps transceiver and enable multiqueueing, I can reach about 80 Gbps on a 100 Gbps interface .

The setup I tested consists of two scenarios with two 29000 appliances for VSX LS:
In the first one, Virtual System 1 is connected to Virtual System 2 through a virtual switch within the VSX environment.
In the second scenario, Virtual System 1 and Virtual System 2 are connected through a physical switch. 

This allows me to directly compare the performance of traffic flows when using virtual switching versus physical switching.

So my questions are:

• What are the limitations of virtual switches in VSX regarding throughput?

• Are virtual switches vs. wrp (Warp Link) capable of using multiple cores for packet forwarding?

[Gera_Dorfman]

We’re not aware of any virtual switch performance limitations in KPPACK. However, I’ll double-check with the team and get back to you. To clarify again - we are aware of the issue with UPPACK and working on a fix. 

[jan-j]

Hi. Any news on double-checking with the teams if this is also an issue on KPPAK? Thx.

[PhoneBoy]

The (apparent) lack of multi-core may be part of the issue here.
Not sure if KPPAK has the same issue or not, but given we will be UPPAK only from R82.10, I expect we'll prioritize fixing it there.

[genisis__]

Maybe I'm thinking too deep about this, but would a VSW not utilise SND Cores to push traffic through, if that is the case, would dynamic balance or hyperflow then kick-in.??  

[PhoneBoy]

As I recall, SND leverages RSS (Receive Side Scaling, not to be confused with Really Simple Syndication).
That happens at the NIC level, as far as I know.
Not sure how that translates to VSes, exactly.

Hyperflow is only relevant to traffic passed in the Medium Path, which I assume is not the case for a VSW.

[genisis__]

Thanks.