topic Re: Ethernet link speeds in General Topics

Ethernet link speeds

BobW — Thu, 11 Oct 2012 04:12:32 GMT

I am curious what the recommended link speed settings for the various ports. The external port has to be hard speedcoded to 100/full as that is required by the ISP. The internal connection is to a gig core switch at auto detect (1000/full).

Should the internal connection be set to 100/full to match the external?

Thanks,

Bob

Re: Ethernet link speeds

ssharma — Thu, 11 Oct 2012 04:19:26 GMT

You can treat both interfaces independently. So the internal traffic can use gig link. Only thing you will have to make sure is two end point between devices have same speed and duplex. Either Auto/Auto or 100/full on both ends. Hope this helps. Thanks.

Re: Ethernet link speeds

mikand — Tue, 16 Oct 2012 03:24:30 GMT

What about buffering issues when one side is 1Gbit (or more) and the other is 100Mbit (or less) in a PA?

Wouldnt it be more efficient to set both sides of the PA to the same speed and let the buffering be dealt with by the routers/switches between the PA and the client(s)?

Re: Ethernet link speeds

BobW — Tue, 16 Oct 2012 04:13:05 GMT

"Wouldn't it be more efficient to set both sides of the PA to the same speed and let the buffering be dealt with by the routers/switches between the PA and the client(s)?"

Exactly what I was wondering....thank you for restating my question correctly.

Bob

Re: Ethernet link speeds

UhMayYeah — Tue, 16 Oct 2012 06:05:55 GMT

I have seen issues in the past ,having mismatched speeds on the internal and external interfaces.

Hard coding the internal speed to match external, helped improving the speed/performance.

-Ameya

Re: Ethernet link speeds

mikand — Tue, 16 Oct 2012 07:40:12 GMT

Speaking of hardcoding this seems to be valid for 10 and 100Mbit links but for 1Gbit and upwards the IEEE standard suggests one to use auto/auto (or auto/full, auto/half).

So if you set one side statically to 1000Mbit it might end up with funny results depending on what you have on the other side.

Note however that this depends on hardware being used. Some hardware when you force it to 1000Mbit will actually still use auto/auto but only propose 1000Mbit as supported speed (instead of 10, 100, 1000 as it would normally do).