""Larry Letterman"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Chuck, > > Originally I got the oversubscribe numbers from extreme a few years ago... > Now days, with fast switches, it makes no real diference...
CL: numbers are always interesting. especially when compared to what the various vendors provide physically. CL: for example, all the major vendors ( Cisco and the "pack" ) sell 48 port boxes with two gig ports, presumably for uplink. Using that "4 to 1" number, all those boxes are at the limit. CL: OTOH, I sometimes think all this "backplane" discussion is overblown. In high end server farms it "might" be likely that all your devices are transmitting AND receiving at close to full wire speed simultaneously. In the user community, however, I would highly doubt that you could find any workgroup in which ALL ( or any significant proportion ) devices were sending and receiving at wire speed > > the rationale is that all ports wont be active at the same time....so > you can > oversubscribe the access switches by 3 or 4 to 1.... > > Chuck's Long Road wrote: > > >""Larry Letterman"" wrote in message > >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > >>Jimmy, > >> > >>The access switch(users) should not be oversubscribed by more than 3 to > >>1....in my opinion.. > >>the total user bandwidth if you have a 12 port switch at 100 mb per port > >>is 1.2 gb...the switch needs to be able to > >>handle at least 400 mb of thruput .... > >> > > > > > >CL: I'm always curious about numbers. Long evenings in night school taking > >management courses. So if you don't mind, what is the rationale for this > >ratio? > > > >CL: just looking for a bit more education.... > > > > > > > >>also the core switches should be faster than the access switches below > >>it.... > >> > >>if the core switch is 100mb, then the user access switches should 10 mb > >>switches with a 100mb > >>uplink to the core.... > >> > >>Jimmy wrote: > >> > >>>First of all, thank for the wonderful response. > >>> > >>>So from what you all have said. If the user is for normal purpose like > >>>running some application on servers and access the Internet. Will a > >>> > >100Mbps > > > >>>be sufficient for 300 users. As for the users, they will be splitted into > >>>several group of around 15-20 each.Or a 10Mbps switch will be more than > >>>sufficient for it. > >>> > >>>Can i calculate the BW for each user in this manner: > >>>100M / 300 (no of user) > >>>Assuming full usage. > >>> > >>>Let say i have around 3 storey of about 300 users each, The backbone > >>> > >switch > > > >>>should be 10x the BW of each floor rite? > >>> > >>>Cheers, > >>>Jimmy > >>> > >>-- > >> > >>Larry Letterman > >>Network Engineer > >>Cisco Systems Inc. > -- > > Larry Letterman > Network Engineer > Cisco Systems Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=54245&t=54023 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
