Francisco H Tapia
my.lists at verizon.net
Tue Nov 4 12:25:20 CST 2003
Would it be helpful to add a 2nd Nic and bind all print job request trough it, and leave the original nic for standard file server access? I don't know how to do this, but I can only imagine that it could be done. throw a Switch in there in place of the hub and you've updated your network w/ 1 nic + the number of switches required. John Colby wrote: >Erwin, > >A collision is when one computer is transmitting and another starts >transmitting over the top of the first. The result of a collision is that >the data is corrupted and has to be retransmitted. > >This can happen in a hub because ALL computers share a single physical >electrical connection. This simply cannot happen with a switch because the >electronics set up a unique electrical connection from computer to computer >using a cross point switch. > >With an eight port switch you could under ideal circumstances have four 100 >mbit conversations going on simultaneously. There would be no collisions at >all, four perfectly completed communications. > >Now obviously if a server is on one port and all the other ports want to >talk to that port then only one at a time can do so, but you still NEVER >have collisions since the electronics simply don't connect port A to port B >unless port B is not in use. > >So yes, you have a bottleneck, all communications needs to go through a >single port to get to the server, but NO, true collisions (one computer >transmitting on top of and corrupting data of another computer) NEVER happen >with a switch. > >John W. Colby >www.colbyconsulting.com > >-----Original Message----- >From: dba-tech-bounces at databaseadvisors.com >[mailto:dba-tech-bounces at databaseadvisors.com]On Behalf Of Erwin Craps >Sent: Tuesday, November 04, 2003 2:07 AM >To: Discussion of Hardware and Software issues >Subject: RE: [dba-Tech] Re: [] Wireless network (sort of) > > >Thats not totaly true. > >Switches prevent collisions and resends to happen on the OTHER virtual >connections. >On A point to point connection you also have collisions. >Because all trafic all goes to one link to the server that link will have >all collisions to, thus taking bandwith of others connections. >Simply because you have a single bottleneck. > >Erwin > >-----Oorspronkelijk bericht----- >Van: dba-tech-bounces at databaseadvisors.com >[mailto:dba-tech-bounces at databaseadvisors.com] Namens John Colby >Verzonden: maandag 3 november 2003 23:33 >Aan: Discussion of Hardware and Software issues >Onderwerp: RE: [dba-Tech] Re: [] Wireless network (sort of) > > >Erwin, > >But none of that takes into account collisions and retransmissions due to >collisions. Hubs have that to deal with, switches don't. > >John W. Colby >www.colbyconsulting.com > >-----Original Message----- >From: dba-tech-bounces at databaseadvisors.com >[mailto:dba-tech-bounces at databaseadvisors.com]On Behalf Of Erwin Craps >Sent: Monday, November 03, 2003 5:21 PM >To: Discussion of Hardware and Software issues >Subject: RE: [dba-Tech] Re: [] Wireless network (sort of) > > >OK, it's me again. > >I still stand with my remarks. I'm implemented a lot of switch several years >ago and am very much aware how layer 2 and 3 switches work. Layer 4 don't >know. Not in to that business anymore. As I already commented it is wrong to >say that switches will always will improve your bandwith. A switch will only >be able to do his thing when some condtions are true. These coditions are >most of the time present but not always. > >But generaly you could conclude a switch will have network performance >effect when >1) 2 servers/hosts or more with each his own direct link to the switch >2) When having only one server the server link bandwith MUST be higher than >the (single) client bandwith. > >It all turns about the slowest link principle. With a switch you create >dynamic virtual connections. The slowest link at that time will decide the >bandwith for that connection. > >Small example. >You have: >1x client A at 100Mbps >1x client B at 100Mbps >1x x-port switch all 100Mbps >1x server S at 100Mbps > >Both clients starts sending large data to the server at maximum speed (let's >say each 100Mbps to make an easy calc). >Question: What will be the maximum network bandwith obtained to the server? >A) 100Mbps >B) 200Mbps >C) 300Mbps > >Right, a) 100 Mbps, why? Because the server has only one 100Mbps link. Will >this go faster than a hub. No. Infact, a switch has to make a decision based >on MAC or IP address and this takes time. So, I would like to believe it >will be slightly slower than a hub... > >If a was talking about speed in my previous mails I could have mixed speed >and bandwith. You have the network speed (should be bandwith), and you have >speed (or >performance) of the switch. >Speed of a switch is the delay (lack of) and the quantity of ethernet >packets it can manipulate per second. > >I remember me some figures (delay times) but I supose they will be much >lower now. A router takes about 600 to 800µsec to make a decision (and >change) to forward a packet to a port based on IP or other layer 3 routable >protocol. A switch took (in 1996 or so) around 180µsec based on Mac. A hub >none... Because it doesn't take a look inside the pakket.. It justs repeats >stupidly. A hub is nothing more than a stupid (bon-intelligent but >active) repeater. > >So if you wanna see bandwith improvement on a single server network you must >have a 1Gb connection to the server (thats what I would suggest) or use dual >link between server and switch. Both server and switch must support dual >links (teamed links?). By this you would have 200Mb between server and >switch and you could now have 2 clients running at full speed (100Mb). I'm >not sure about this dual link if both are full duplex, maybe it depends on >the brand but I believe I read somewhere that with a dual link you have >100Mb upstream and 100mb downstream. Which would result that when both >clients are sending they only would have 50 Mb each. If one would send other >receive they would have each 100Mbps. > >This is the theoricatal best situation because, if you don't have a heavely >loaded network, you will have more bandwith, but not used. It's like having >a east-west coast pipeline and you only send a drop of water trough it... >The switch is of no use due to lack of trafic. You would better put your >money in a good server or applications or new pc's... > >But hey, don't get me wrong. I'm 100% pro switches. If you are having doubts >for buying a switch or a hub, buy a switch. You gonna need it someday. >Prices are down, but I'm not that sure if performance of those cheap ones >are good. > >But don't say switches will always improve speed. It really depends on your >network configuration. > >Erwin > > > > > >-----Original Message----- >From: dba-tech-bounces at databaseadvisors.com >[mailto:dba-tech-bounces at databaseadvisors.com] On Behalf Of Francisco H >Tapia >Sent: Monday, November 03, 2003 8:11 PM >To: Discussion of Hardware and Software issues; jimdettman at earthlink.net >Subject: [dba-Tech] Re: [] Wireless network (sort of) > > >Jim, > I'm replying to the dba-tech list as that is the proper list for this topic >:). On that note, some of your more recent Switches also come w/ somthing >called spanning trees. > >Jim Dettman wrote: > > > >>Drew/Erwin, >> >> One minor correction. Switches don't use NAT tables. They use MAC >>Address lists and ARP tables. NAT is something done only in a router. >> >>Jim Dettman >>President, >>Online Computer Services of WNY, Inc. >>(315) 699-3443 >>jimdettman at earthlink.net >> >>-----Original Message----- >>From: accessd-bounces at databaseadvisors.com >>[mailto:accessd-bounces at databaseadvisors.com]On Behalf Of Drew Wutka >>Sent: Monday, November 03, 2003 11:59 AM >>To: 'Access Developers discussion and problem solving' >>Subject: RE: [AccessD] OT: Wireless network (sort of) >> >> >>Read Erwins post a little while ago, was waiting for your's before I >>replied! <grin> >> >>Erwin, switches also use NAT tables. Because of this, they don't have >>to broadcast everything in all directions. They're 'smart', when a >>packet comes in, they can properly direct it. The downside to the NAT >>tables is that if you blow the NAT table away, it has to be rebuilt, so >>sometimes on an initial powerup, a switch may seem slower, which is >>simply the time it is using to build the NAT tables. >> >>Drew >> >>-----Original Message----- >>From: Frank Tanner III [mailto:pctech at mybellybutton.com] >>Sent: Sunday, November 02, 2003 8:35 AM >>To: Access Developers discussion and problem solving >>Subject: RE: [AccessD] OT: Wireless network (sort of) >> >> >>And they improve speed. >> >>Because they do not SHARE the bandwidth amongst the >>ports. A 10-BaseT hub SHARES that speed amongst the >>available ports. This dividing the individual >>bandwidth per port. >> >>A switch allocates all available bandwidth on a PER >>PORT basis. >> >>Maybe you need to learn what you are talking about >>before you give out false information. >> >>--- Erwin Craps <Erwin.Craps at ithelps.be> wrote: >> >> >> >> >>>And to be correct, switches don't improve speed >>>(compared to hub's) they >>>improve bandwith and reduce collisions!!! >>>Switches create virtual point to point connections. >>> >>>Switches do improve speed compared to routers. >>> >>>Erwin >>> >>>-----Oorspronkelijk bericht----- >>>Van: accessd-bounces at databaseadvisors.com >>>[mailto:accessd-bounces at databaseadvisors.com] Namens >>>Frank Tanner III >>>Verzonden: zaterdag 1 november 2003 16:23 >>>Aan: Access Developers discussion and problem >>>solving >>>Onderwerp: RE: [AccessD] OT: Wireless network (sort >>>of) >>> >>> >>>Switches will ALWAYS improve your speed over hubs. >>>Period. >>> >>>Hubs SHARE the same bandwidth on all ports. >>>Switches >>>allocate the max bandwidth per port. >>> >>>You are incorrect. >>> >>>--- Erwin Craps <Erwin.Craps at ithelps.be> wrote: >>> >>> >>> >>> >>>>But switches have no sense in a 1 server >>>> >>>> >>>> >>>> >>>environment >>> >>> >>> >>> >>>>because all of the >>>>trafic goes and comes from one point. >>>>Unless your clients are 100Mb and the uplink to >>>> >>>> >>>> >>>> >>>the >>> >>> >>> >>> >>>>server is 1Gb. >>>> >>>>People often believe switches will improve their >>>>network speed, but that >>>>is not always the case. >>>>But indeed the prices of the switches have dropped >>>>that you buy a switch >>>>at the price of a good hub these days. >>>> >>>>Erwin >>>> >>>>-----Original Message----- >>>>From: accessd-bounces at databaseadvisors.com >>>>[mailto:accessd-bounces at databaseadvisors.com] On >>>>Behalf Of Rocky Smolin >>>>- Beach Access Software >>>>Sent: Saturday, November 01, 2003 1:55 AM >>>>To: Access Developers discussion and problem >>>> >>>> >>>> >>>> >>>solving >>> >>> >>> >>> >>>>Subject: Re: [AccessD] OT: Wireless network (sort >>>>of) >>>> >>>> >>>>Got it. I think. Switch can route packet based on >>>>IP address but can't >>>>generate an IP address. Yes? >>>> >>>>Rocky >>>> >>>> >>>>Rocky >>>> >>>>----- Original Message ----- >>>>From: "Frank Tanner III" >>>> >>>> >>>> >>>> >>><pctech at mybellybutton.com> >>> >>> >>> >>> >>>>To: "Access Developers discussion and problem >>>>solving" >>>><accessd at databaseadvisors.com> >>>>Sent: Friday, October 31, 2003 10:29 AM >>>>Subject: Re: [AccessD] OT: Wireless network (sort >>>>of) >>>> >>>> >>>> >>>> >>>> >>>> >>>>>It is sort of half-way, but not really. >>>>> >>>>>Switches are a "generation" better. Hubs and >>>>>switches, on their most basic level perform the >>>>> >>>>> >>>>> >>>>> >>>>same function. They >>>> >>>> >>>> >>>> >>>>>distribute network traffic. But HOW they >>>>> >>>>> >>>>> >>>>> >>>>distribute that traffic is >>>> >>>> >>>> >>>> >>>>>fundimentally different. >>>>> >>>>>Unless they're one of the newer layer 3 or layer >>>>> >>>>> >>>>> >>>>> >>>4 switches, they >>> >>> >>> >>> >>>>>cannot perform routing functions. >>>>> >>>>> >>>>> >>>>> >>>>They >>>> >>>> >>>> >>>> >>>>>just hand packets off from point A to point B. >>>>> >>>>> >>>>> >>>>> >>>>Think >>>> >>>> >>>> >>>> >>>>>of them as sort of a postman. They have an >>>>> >>>>> >>>>> >>>>> >>>>address >>>> >>>> >>>> >>>> >>>>>for each device on the network and they hand off >>>>> >>>>> >>>>> >>>>> >>>>each >>>> >>>> >>>> >>>> >>>>>piece of mail to the appropriate address. A >>>>> >>>>> >>>>> >>>>> >>>hub, >>> >>> >>> >>> >>>>>using this sama analagy would deliver the same >>>>> >>>>> >>>>> >>>>> >>>>piece >>>> >>>> >>>> >>>> >>>>>of mail to every house and the one that it >>>>> >>>>> >>>>> >>>>> >>>>belonged to >>>> >>>> >>>> >>>> >>>>>would be the one that actually reads it. >>>>> >>>>>--- Rocky Smolin - Beach Access Software >>>>> >>>>> >>>>> >>>>> >>><bchacc at san.rr.com> wrote: >>> >>> >>> >>> >>>>>>"but it's as close as I could think of without >>>>>>getting too technical." >>>>>> >>>>>>Thank you. Much appreciated. So a switch is >>>>>> >>>>>> >>>>>> >>>>>> >>>>like >>>> >>>> >>>> >>>> >>>>>>halfway between a hub and >>>>>>a router? >>>>>> >>>>>>Rocky >>>>>> >>>>>>----- Original Message ----- >>>>>>From: "Frank Tanner III" >>>>>> >>>>>> >>>>>> >>>>>> >>>><pctech at mybellybutton.com> >>>> >>>> >>>> >>>> >>>>>>To: "Access Developers discussion and problem >>>>>>solving" >>>>>><accessd at databaseadvisors.com> >>>>>>Sent: Friday, October 31, 2003 7:36 AM >>>>>>Subject: Re: [AccessD] OT: Wireless network >>>>>> >>>>>> >>>>>> >>>>>> >>>>(sort >>>> >>>> >>>> >>>> >>>>>>of) >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>A router and a switch are fundimentall >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>different >>>> >>>> >>>> >>>> >>>>>>>things. >>>>>>> >>>>>>>A router does just that. It routes network >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>traffic. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>A switch plays "traffic cop" for a network. >>>>>>> >>>>>>>Newer switches, especially the layer 3 and >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>layer 4 >>>> >>>> >>>> >>>> >>>>>>>ones can perform both functions.This isn't >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>an >>> >>> >>> >>> >>>>>>exact >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>definition, but it's as close as I could >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>think >>> >>> >>> >>> >>>>of >>>> >>>> >>>> >>>> >>>>>>>without getting too technical. >>>>>>> >>>>>>>--- Rocky Smolin - Beach Access Software >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>><bchacc at san.rr.com> >>>> >>>> >>>> >>>> >>>>>>>wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>>>Is there a difference between a switch and >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>a >>> >>> >>> >>> >>>>>>router? >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>>Rocky >>>>>>>> >>>>>>>>----- Original Message ----- >>>>>>>>From: "Frank Tanner III" >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>><pctech at mybellybutton.com> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>>To: "Access Developers discussion and >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>problem >>>> >>>> >>>> >>>> >>>>>>>>solving" >>>>>>>><accessd at databaseadvisors.com> >>>>>>>>Sent: Friday, October 31, 2003 6:54 AM >>>>>>>>Subject: RE: [AccessD] OT: Wireless >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>network >>> >>> >>> >>> >>>>>>(sort >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>>of) >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>>I recommend "hardwiring" the IP address >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>of >>> >>> >>> >>> >>>>any >>>> >>>> >>>> >>>> >>>>>>>>device >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>>or server connected to your LAN that's >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>not >>> >>> >>> >>> >>>>a workstation and >>>> >>>> >>>> >>>> >>>>>>>>>is virtually always on. >>>>>>>>> >>>>>>>>>For the price, I would also highly >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>recommend >>>> >>>> >>>> >>>> >>>>>>>>removing >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>>all hubs from your network and using >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>them >>> >>> >>> >>> >>>>as doorstops. >>>> >>>> >>>> >>>> >>>>>>>>>Switches have come way down in >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>price >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>>and >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>>have many benifits over hubs. >>>>>>>>> >>>>>>>>>Hubs divide the bandwidth across all >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>ports. >>>> >>>> >>>> >>>> >>>>>>Thus >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>>if >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>>you have an 8-port 10-BaseT hub, all >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>ports >>> >>> >>> >>> >>>>>>that >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>>>are >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>>processing data split that 10Mbit. A >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>=== message truncated === >> >> >> > > -- -Francisco