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Mac Forum / General / Networking / August 2004will cable modem be faster w/100base-T?
I have four macs hooked up to a LAN. The LAN goes to a router, then a cable modem. All the macs are 10 base-T (built in) The hub and router are 100 base-T Question: Will my internet experiences improve if I upgrade the Macs to 100Base-T? I mostly use my PPC 7500/300 and DT G3/266 The NICs are just under $10.00 but I won't get them unless I know they'll be of any benefit to me. SIDE NOTE: Would these slow machines transfer files to each other faster with a 100Base card? I use one to backup the other, so large file transfers are common. Have a great day......and Thanks.......DaveC...... > Will my internet experiences improve if I upgrade the Macs to 100Base-T? No. > Would these slow machines transfer files to each other faster with a > 100Base card? Yes.  SignatureMike Rosenberg <http://www.macconsult.com> Macintosh consulting services for NE Florida <http://bogart-tribute.net> Tribute to Humphrey Bogart Toyota Prius fans: Check out alt.autos.toyota.prius > I have four macs hooked up to a LAN. > The LAN goes to a router, then a cable modem. > All the macs are 10 base-T (built in) > The hub and router are 100 base-T > Question: > Will my internet experiences improve if I upgrade the Macs to 100Base-T? It depends on how fast your cable modem connection to the internet is. Most likely you'd see no difference, but you might see an improvement if your cable modem is faster than 10Mbps. > I mostly use my PPC 7500/300 and DT G3/266 > The NICs are just under $10.00 but I won't get them unless I know they'll be [quoted text clipped - 3 lines] > Would these slow machines transfer files to each other faster with a 100Base > card? I use one to backup the other, so large file transfers are common. Yes, this would improve. SignatureTom "Tom" Harrington Macaroni, Automated System Maintenance for Mac OS X. Version 2.0: Delocalize, Repair Permissions, lots more. See http://www.atomicbird.com/ > > I have four macs hooked up to a LAN. > > The LAN goes to a router, then a cable modem. [quoted text clipped - 6 lines] > Most likely you'd see no difference, but you might see an improvement if > your cable modem is faster than 10Mbps. Are there any cable modem services that fast yet? Last year Comcast bumped us up to 3Mbps, and recently announced an extra-cost offering that gets you 4Mbps. I think I've heard of another cable modem service announcing 6Mbps. And all these are just theoretical maximums, not guaranteed throughput speeds. Few web sites are able to deliver content at these speeds (if they have that much bandwidth at the server end, it's probably because they're serving lots of clients concurrently), so even if you could get all that bandwidth it would only be noticeable when you were doing several downloads from different locations simultaneously. SignatureBarry Margolin, barmar@alum.mit.edu Arlington, MA *** PLEASE post questions in newsgroups, not directly to me *** > > > I have four macs hooked up to a LAN. > > > The LAN goes to a router, then a cable modem. [quoted text clipped - 18 lines] > all that bandwidth it would only be noticeable when you were doing > several downloads from different locations simultaneously. An interesting side question. When the cable service goes up to 3Mbits or higher download speeds, do they also increase the uplink speed? I'm thinking that download traffic needs a minimum amount of ACKs that have to be returned for every so many messages received. If they keep increasing "Just" the download speed, but keep the default 128Mbits uplink speeds, then they will effectively throttle the usage by limiting how fast and how often the user can ACK the download traffic. Neat trick. Burst download speeds are some fantastic number, but overall through put is limited by the uplinks ability to return ACKs. I know just enough to be a danger to myself, so someone with more detailed knowledge of TCP/IP, FTP and/or HTTP protocols and their ACK requirements would be better able to able to calculate the unlink bandwidth needed to download at a given speed. Bob Harris > An interesting side question. When the cable service goes up to 3Mbits > or higher download speeds, do they also increase the uplink speed? I'm [quoted text clipped - 5 lines] > trick. Burst download speeds are some fantastic number, but overall > through put is limited by the uplinks ability to return ACKs. They do often increase the uplink speeds, although I don't know if it's always proportional. However, unless you're uploading files at the same time as you're downloading, you're not going to saturate the uplink. ACKs are *really* small -- about 60 bytes, compared with 1500 bytes/packet for the downloading data. And TCP normally only ACKs every other received packet, so you're sending 60 bytes for every 3000 bytes received. So if the ratio of downlink:uplink is less than 50:1, it should be able to keep up when the uplink is otherwise idle. And even if the receiver can't keep up with this, TCP adjusts to accomodate. SignatureBarry Margolin, barmar@alum.mit.edu Arlington, MA *** PLEASE post questions in newsgroups, not directly to me *** > They do often increase the uplink speeds, although I don't know if it's > always proportional. When comcast doubled the downlink cap to 3Mbps last year, they didn't increase the uplink speed. The ratio now is something like 20:1. As Barry says, it has to get a lot higher than this for asymmetry to be a problem (unless there's competing uplink traffic). I remember reading a number of papers on this topic in the late 90s, only one of which I can find right now: "The Effects of Asymmetry on TCP Performance" by Hari Balakrishnan et al: http://nms.lcs.mit.edu/~hari/papers/tcpasym-mobicom97.ps.gz For some reason Preview.app displays the pages of the postscript file in reverse order. > And even if the receiver can't keep up with this, TCP adjusts to > accomodate. But of course this means the "extra" downlink speed can never be used effectively: the provider would be better off capping the downlink at a lower speed in the first place. To put it another way, for any given uplink speed, there's a maximum downlink speed beyond which any increase is counter productive. > An interesting side question. When the cable service goes up to 3Mbits > or higher download speeds, do they also increase the uplink speed? Comcast kept the upload speed at 256K when they raised the download speed. BellSouth DSL's new 3Mbs option includes 384K upload speed. SignatureMike Rosenberg <http://www.macconsult.com> Macintosh consulting services for NE Florida <http://bogart-tribute.net> Tribute to Humphrey Bogart Toyota Prius fans: Check out alt.autos.toyota.prius > > > I have four macs hooked up to a LAN. > > > The LAN goes to a router, then a cable modem. [quoted text clipped - 11 lines] > that gets you 4Mbps. I think I've heard of another cable modem service > announcing 6Mbps. Beats me. I know that cable companies claim to be increasing speeds all the time, but I don't follow the details too closely. I tried to give an explanation that would be useful over the long term. SignatureTom "Tom" Harrington Macaroni, Automated System Maintenance for Mac OS X. Version 2.0: Delocalize, Repair Permissions, lots more. See http://www.atomicbird.com/ In article <tph-1477CB.22023128082004@localhost>, Tom Harrington > > Are there any cable modem services that fast yet? Last year Comcast > > bumped us up to 3Mbps, and recently announced an extra-cost offering > > that gets you 4Mbps. I think I've heard of another cable modem service > > announcing 6Mbps. Comcast 4mbps service is a "small business" option. The cost is $80/month per user and is a yearly contract. Minimum of 10 users with a setup cost of $99 per user. If my math is correct that is base outlay of $10,590 in the first year. Signature"All music is folk music. I ain't never heard no horse sing a song." - Louis Armstrong |
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