On 1/12/2011 8:53 PM, Adam Levin wrote: > On Wed, 12 Jan 2011, John BORIS wrote: >> The only thing between the servers I am testing is the electronics of >> the switch. they attach to the same switch. > Ok, I'm not a network engineer (INANE? Hoo, boy!) so someone can correct > me if I'm wrong, but I keep seeing references to ports on the switch. The > ports on the switch have pretty much nothing to do with IP traffic unless > the switch is layer 3, in which case it's more than a switch. :) > > A switch is layer 2, so it's only dealing with ethernet (MAC addresses and > ARP tables, not IP addresses and routing tables). If the web server > machine and your client machine are on two different subnets, then the > network traffic is going to leave the switch and go to a router somewhere > regardless of whether the two machines are plugged into switch ports that > are next to each other. > > Now, if the two machines are on the *same* IP subnet, they would not be > dealing with routing at all, and if the switch were smart enough, it would > pass the packets to the correct MAC address and not bother sending the > packets upstream anywhere. > > I may have missed the part where you mentioned what the IP network > addressing scheme is at your place. > The lines between switch and router have blurred to such an extent that switch is a nearly meaningless term these days without saying L2 or L3 behind it (some even have L4+!). As you note, the L3 switch is basically a router, but it's also a fully capable L2 switch that can forward packets from one port to another on the same broadcast domain (VLAN). It can also do trunking, sometimes firewall functionality, often an exterior routing protocol, and a host of other things like multi-link multi-switch failover handling (various vendor-proprietary names).
so, your second paragraph is only true if the switch is a pure L2 switch. Almost all HP switches, for instance, are L3 capable, so it's perfectly reasonable for his switch to not have to send packets to a router. The vlan just needs to have an IP address associated with it on the L3 switch and voila, it's also now a routing interface, so long as the hosts on the vlan point to it as the default gateway. _______________________________________________ Tech mailing list Tech@lists.lopsa.org https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
