Re: Links on the blink - reprise
At 05:47 PM 11/17/95 -0500, Sean Doran wrote:
There are substantial disadvantages, too.
In order to take advantage of the greater port-density(-per-dollar) on FR switches right now, the end user has to use FR, which is not always practical or desirable.
One of the reasons why end users find frame-relay undesireable is that they cannot be assured that their provider is not grossly oversubscribed on PVC-per-port density. When you buy a T1 private line, you can be assured that you're not sharing it with 120 other end-users. :-) - paul
When you buy a T1 private line, you can be assured that you're not sharing it with 120 other end-users. :-)
A T-1 private line to what? Do you think Sprint has sold more than 30 T-1s, filling up their DS-3 backbone? Do you think MCI has sold more than 30 T-1s, filling up their DS-3 backbone? You _are_ sharing bandwidth, unless 100% of your traffic is to your provider.
- paul
Ehud -- Ehud Gavron (EG76) gavron@Hearts.ACES.COM
On Fri, 17 Nov 1995, Ehud Gavron wrote:
When you buy a T1 private line, you can be assured that you're not sharing it with 120 other end-users. :-)
A T-1 private line to what? Do you think Sprint has sold more than 30 T-1s, filling up their DS-3 backbone?
Do you think MCI has sold more than 30 T-1s, filling up their DS-3 backbone?
You _are_ sharing bandwidth, unless 100% of your traffic is to your provider.
Yes, that is true but most ISP's in my area are overselling 100 X or more. Sure I mux 4 T1 FR to 1 T1 port and oversell my bandwidth, but all of my links have at least 20% free on them during our peek. Sure oversell, but I think it is wrong to keep overselling when your links are at 90% - 100% most of the time and you sell more t1's to get the money. Nathan Stratton CEO, NetRail, Inc. Your Gateway to the World! --------------------------------------------------------------------------- Phone (703)524-4800 NetRail, Inc. Fax (703)534-5033 2007 N. 15 St. Suite 5 Email sales@netrail.net Arlington, Va. 22201 WWW http://www.netrail.net/ Access: (703) 524-4802 guest ---------------------------------------------------------------------------
] Yes, that is true but most ISP's in my area are overselling 100 X or ] more. Sure I mux 4 T1 FR to 1 T1 port and oversell my bandwidth, but all ] of my links have at least 20% free on them during our peek. What is your sample interval? Cisco's 5 minute average? 80% utilization at 5 minute samples means it is very likely the lines are choked a good portion of that time. -alan
On Sat, 18 Nov 1995, Alan Hannan wrote:
] Yes, that is true but most ISP's in my area are overselling 100 X or ] more. Sure I mux 4 T1 FR to 1 T1 port and oversell my bandwidth, but all ] of my links have at least 20% free on them during our peek.
What is your sample interval? Cisco's 5 minute average?
80% utilization at 5 minute samples means it is very likely the lines are choked a good portion of that time.
No, 1 min averages, the liks is normally under 40% used. If it get a lot of 80% 1 min averages we will upgrade the link. Nathan Stratton CEO, NetRail, Inc. Your Gateway to the World! --------------------------------------------------------------------------- Phone (703)524-4800 NetRail, Inc. Fax (703)534-5033 2007 N. 15 St. Suite 5 Email sales@netrail.net Arlington, Va. 22201 WWW http://www.netrail.net/ Access: (703) 524-4802 guest ---------------------------------------------------------------------------
There are substantial disadvantages, too.
In order to take advantage of the greater port-density(-per-dollar) on FR switches right now, the end user has to use FR, which is not always practical or desirable.
One of the reasons why end users find frame-relay undesireable is that they cannot be assured that their provider is not grossly oversubscribed on PVC-per-port density. When you buy a T1 private line, you can be assured that you're not sharing it with 120 other end-users. :-)
Nor can you know that with a Dedicated line, that the other side doesn't feed into a 2501 into a collision-ridden Boca 10baseT hub, into a Welfleet bridging over Frame-Relay-over-ATM at 1.5Mbps simplex speeds into an over-committed 4Mbps port speed on the other side. i.e., the fact that your buying a leased line to connect and running HDLC over it doesn't count for anything. When it comes right down to it, customers can't really be reassured of anything. But then, nobody expects the customer to realize this, right? Dave -- Dave Siegel President, RTD Systems & Networking, Inc. (520)623-9663 Systems Consultant -- Unix, LANs, WANs, Cisco dsiegel@rtd.com User Tracking & Acctg -- "Written by an ISP, http://www.rtd.com/ for an ISP."
In message <199511180045.RAA12135@seagull.rtd.com>, Dave Siegel writes:
Nor can you know that with a Dedicated line, that the other side doesn't feed into a 2501 into a collision-ridden Boca 10baseT hub, into a Welfleet bridgin g over Frame-Relay-over-ATM at 1.5Mbps simplex speeds into an over-committed 4Mbps port speed on the other side.
i.e., the fact that your buying a leased line to connect and running HDLC over it doesn't count for anything. When it comes right down to it, customer s can't really be reassured of anything.
What are you talking about. You can go back and tell your provider that you are losing one packet per 10^-5 and expect them to actually do something to fix it with a leased line. You can't do that with FR unless your PVC CIR is wire speed or you traffic shape to your CIR. Who do you buy leased lines from? Nobody we buy from. If you are talking about a tiny provider buying a T1 from a larger IP provider, you might want to find another provider if that is your impression. I think the discussion was building a backbone though. Curtis
don't confuse the link encoding with back-haul design if the network is deeply over-subscribed, you will drop packets. the only question is "where?" whether the link uses F/R-1490 framing or cisco HDLC doesn't change that. -mo
participants (7)
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Alan Hannan -
Curtis Villamizar -
Dave Siegel -
Ehud Gavron -
Mike O'Dell -
Nathan Stratton -
Paul Ferguson