> -----Original Message----- > From: Alexander Duyck [mailto:alexander.du...@gmail.com] > Sent: Tuesday, March 20, 2018 3:07 PM > To: Ran Shalit <ransha...@gmail.com> > Cc: e1000-devel@lists.sourceforge.net > Subject: Re: [E1000-devel] How is it that a switch gives better boot time > ? > > On Tue, Mar 20, 2018 at 2:33 PM, Ran Shalit <ransha...@gmail.com> wrote: > > Hello, > > > > We tested the time it gets for successful boot from powerup, and we > > are surprised to see that using a switch in the middle (100M) gives > > better result. > > I don't understand how it can be. > > Setting up a 100M connection is much simpler than setting up a 1G > connection. It is not surprising that it would be quicker to setup a > 100M when you have auto-negotiation enabled on both ends. There are 4 > channels per direction versus the 1 in the case of 100M, there is a > broader spectrum in use versus the 100M, there is the auto MDI-X which > you have to do with 1G, that you don't have to do with 100M. There end > up being a ton of differences that make link setup much more expensive > and time consuming for a 1G link. You can refer to the Wikipedia link > below for more info: > https://en.wikipedia.org/wiki/Ethernet_over_twisted_pair > > Thanks. > > - Alex >
Another factor can be spanning tree. If the original 1Gbps link has spanning-tree active, it can easily add a minute (or more) for the switch port to go from "listening" to "learning" to "forwarding". By inserting the 100Mbps switch in between, the 1Gbps link port remains in the "forwarding" state and doesn't have to go through the learning process. - Don ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ E1000-devel mailing list E1000-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired
