On 2013-12-30 13:39, Jakob Unterwurzacher wrote: > On 29.12.2013 01:21, rkwesk_ltsp wrote: >> >> As the switch's port to the client is also 100 Mps I think the >> client's >> 100mps nic cannot be overloaded >> per se. However, a fellow member of this list, alkisg, has since >> explained to me that the buffer on the >> switch will fill up since it is receiving packets from its giga port >> but can only release them at its >> 100 mbps port. It was this phenomenon (is it called buffer overrun?) >> that I hadn't thought about. This >> then forces the switch to send a pause frame to the server (in order >> for its buffer to be relieved.) > > Yes, exactly. > I wouldn't call it buffer overrun - that would imply a programming > bug. > The buffer just gets full.
Ah, thank you. >> Now I will show complete ignorance by asking whether if in fact the >> overload occurs even sooner (or more often) >> if an all giga switch were in place of the above described switch >> and >> the bottleneck was the 100 mbps nic rather >> than the 100 mbps port on the above switch? > > Whether it is a 100Mb port or a gigabit port operating at 100Mb does > not > make a difference. > The bottleneck will be the switch port (not the NIC!) that cannot get > the data out as fast as the gigabit port gets new data in. > > > Jakob Thank you for clearing that up. A very Happy New Year to everyone!! Thus the summing up is that the "gain" one has in buying a switch with only 1 or 2 gigaports rather than an all giga switch is the initial cost. The particular switch, http://www.tp-link.com/lk/products/details/?model=TL-SL1117 was purchased for 51 euros. However, the burden then must fall to the server to disable flow control on its giga nic. If, instead, one purchases one of these options: 1 - a motherboard with an onboard giga nic that responds to a parameter that disables flow control, or 2 - a second giga nic that can fit in an available slot on the server that will respond, or 3 - a managed switch that one may disable the passing of pause packets back to the server. If my understanding is correct, disabling flow control will allow the server's nic to slow down (rather than pause.) Would it be too much to hope for to say that no packet is lost just that the switch's buffer gets the chance to handle any other packets for other clients in addition to coping with the particular client's needs? Richard ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _____________________________________________________________________ Ltsp-discuss mailing list. To un-subscribe, or change prefs, goto: https://lists.sourceforge.net/lists/listinfo/ltsp-discuss For additional LTSP help, try #ltsp channel on irc.freenode.net
