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Re: Links on the blink - reprise
by Sean Doran 20 Nov '95

20 Nov '95

Curtis - | The brick wall is that a particular piece of equipment from a particular | vendor that a lot of service providers have made a large investment in | doesn't really perform all that well in the real world. Please allow me to mitigate your politics with a dose of reality. sl-dc-8.sprintlink.net, a now-fairly-old Cisco 7000 with one of the first four 2MB SSP boards ever shipped outside Cisco's doors has been observed to switch 125kpps through several interfaces over a 15 minute period several times in the past three weeks. The bottleneck is not in terms of switching capacity nor is it in terms of throughput across its backplane at present. The latter issue is looming, but we're simply not there yet. There have been substantial problems with respect to convergence times. Many of these have been ameliorated with experimental code now deployed throughout SprintLink and ICM, which does selective packet dropping to assist convergence rather than having the box keel over dead process-switching packets when the SSE cache is being completely repopulated. We are no longer hovering close to the practical limits of the current limitation, and are not very near the reasonable maximum for the current platform. This is not to say that we have all that much breathing-room, but this and other developments in the works does and will buy us much more time than we would gain by moving towards a system of the kind other providers appear to favour. The immediate danger is still in terms of BGP routing on defaultless routers, and we are all now keenly aware of that and I believe that even you have accepted that despite available alternatives like dedicated route servers, we must CIDRize or die. I am shocked and surprised to see you insinuating that my colleagues here and elsewhere and I simply don't know what the hell we're doing or what we're installing in our backbones. We are all too keenly aware that the growth of much of the Internet is outpacing the ability to build correctly-sized equipment and is forcing most of us to design plans for the deployment of large, scalable and for now over-engineered routers to cope with the current trends in traffic increases which do not look like they're going to shrink before the end of 1997. Not all of us are in the enviable position of being able to sit back and enjoy the air of superiority that seems to accompany being the chief commentator for a once-important and formerly leading-edge backbone. I think that you will find that at least two organizations who aren't in that position have been pushing Cisco very hard on the rather ingenious idea of developing an ISP test lab wherein real problems can be reproduced and studied, and where the characteristics of the current and in-development router technologies with respect to heavy-duty ISP environments can better be understood. You'll probably say that this is all familiar and old-hat, but kindly put your sneer aside and remember that the NSFNET backbone service ended a doubling and a quarter ago with respect to the size of the Internet then and now. These problems are difficult, nobody has complete answers, and "gee, just turn off a whole bunch of customers and you'll be fine" doesn't strike me as a plausible solution for Sprint, MCI, or AlterNet. Sean. P.S.: You might want to consider some "Sprint-did-it-firsts" which developed both within ICM and SprintLink vis a vis Cisco and general router technology deployment: 7000s, 64Mb RPs, BGP4, SSPs, 2MB SSPs, 7500s, reprioritization of forwarding vs other tasks, selective packet drop, and so on and so forth. Vadim Antonov and Peter Lothberg were and are never idle, and I fully intend to carry on the tradition of pushing useful new technology into the field as fast as it is available, because quite frankly, we need it all. DS3? OC3? Hah. You ain't seen nothing yet, baby.

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Kind Words of Caution
by Tim Bass 20 Nov '95

20 Nov '95

Nanog, Before we begin to retire into the slow holiday mode of operation, I would like to offer this simple thought as a word of caution for those engaged in internetworking discussions. Last week, someone asked a valid question about pending and potential problems with aggregation and address space portability issues. The initial response was a statement validating that concern with hopes of a developing a fruit bearing discussion on this very controversial " in the closet " topic. The public process then followed the common disturbing direction that always clouds the issues (especially on the potential non-technical problems of aggregation) and effectively destroyed any prospect of meaningful interchange. I kindly caution many on this list, as internetworking topics are discussed related to Internet operations, *not* to be seduced by those skillful at pedantic discussions that obfuscate any controversial position that they disagree. Especially on the Internet, many are seduced by those who obfuscate the facts by pedantic side discussions and this important list is no exception. For those of you who are not familar with the English word "pedant" I kindly include a short blurb from Websters dictionary. pedant, n. 1. a person who makes an excessive or inappropriate show of learning. 2. a person who overemphasizes rules or minor details.... I kindly caution those unfamiliar with pedantic postings and the use of pedanticism on mailing lists to understand when to recognize these email postings and responses that tend to be pedantic in nature. Pedanticism can be used very effectively to seduce the public into refocusing the discussion from a logical argument that cannot be won nor argued convincingly, to one that is tangential to the topic. Often these pedantic responses clearly and effectively allow the poster to change the subject and then demonstrate their "knowledge" in a tangential or related subject area which they are well versed. As you can see, this clearly obfuscates the original concerns and issues. As we approach 1996, I only caution out of kind regard for tangible progress in building internet services to practice recognizing when 'hawks and eagles' and other high flying posters enjoy easily seducing the general audience with pedanticism, either intentional or unintenional. Practicing, in your own mind, to discern and recognize pedantic email discussions helps all of us who care about enjoying 'meaningful, tangible discussions' to think with clear comprehension. It is very well documented in civilized history that pure intellect and logic without attempting to include elements of patience and kindness, is *not* wisdom. Wisdom is the pursuit and practice of intellect with patience and understanding of others. For all of us, especially me, the pursuit of changing raw technical excellence to refined wisdom is a very challenging life pursuit. I work daily to improve my self-awarenedd in this area because, as an electrical engineer, I once believed that the 'intellect of building systems' was more important than the 'less intelligent ' society we engineer systems to benefit. This manner of thinking is clearly flawed and those, including myself, who are attracted to 'higher education' and intellectual pursuits have a nature human tendency to be seduced by this incomplete position. What is less common is to find those same individuals who recognize this and tend to pursuit wisdom as well as intellect. Kind Regards, Tim PS: Please enjoy safe travel during the holiday weekend. I'm heading out to stay with family in Tennessee and face a long 10 hour drive as well. +--------------------------------------------------------------------------+ | Tim Bass | #include<campfire.h> | | Principal Network Systems Engineer | for(beer=100;beer>1;beer++){ | | The Silk Road Group, Ltd. | take_one_down(); | | | pass_it_around(); | | http://www.silkroad.com/ | } | | | back_to_work(); /*never reached */ | +--------------------------------------------------------------------------+

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Re: Kind Words of Caution
by Sean Doran 19 Nov '95

19 Nov '95

WhatEVER. Sean.

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RE: Links on the blink - reprise
by Paul Ferguson 19 Nov '95

19 Nov '95

At 09:17 AM 11/19/95 -0500, Jeffrey P. Oliveto wrote: > >DS3/DS1 Backbone/Trunk capacity planning principles, whether across a Frame >Relay Backbone or Cisco 7000 hdlc trunk network are still the same. It's >just as easy to over configure DS3/DS1 Cisco HDLC trunks as Frame Relay >trunks. > I would have a tendency to disagree with you here, but que sera, sera. >Potentially at issue here is not Frame Relay networks as a transport but that >a Cisco 7000 can not scale properly to support 120+ end-users. :-) > >Modern Frame Relay switches: > >1) have sub-msec latency >2) can support multiple trunks at DS3+ (to include ATM) >3) are not burdened with processing any of the IP layer 3 nor routing overhead >4) because of 3 have a cost per port that is 300 to 400% less than a Cisco 7000 >5) can have it's backbone shared across multiple services thereby reducing both >capitalization and bandwidth expense >6) allow ISP to pass the cost savings on to customers > > I partially agree with your points above, but still maintain that it is much easier to sloppily engineer a frame-relay network than one consisting of point-to-point links. My $.02. - paul

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Re: Links on the blink - what will/should mci & sprint do?
by sob＠academ.com 19 Nov '95

19 Nov '95

Sean Doran writes: > No, what a disaster would mean is replacing backbone 7500s > with 7000s Sean, are there actually backbone 7500s in production? I thought that was yet to come. Did I misread something here? -- Stan | Academ Consulting Services |internet: sob(a)academ.com Olan | For more info on academ, see this |uucp: {mcsun|amdahl}!academ!sob Barber | URL- http://www.academ.com/academ |Opinions expressed are only mine.

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RE: Links on the blink - reprise
by Jeffrey P. Oliveto 19 Nov '95

19 Nov '95

Paul; You state: 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. :-) DS3/DS1 Backbone/Trunk capacity planning principles, whether across a Frame Relay Backbone or Cisco 7000 hdlc trunk network are still the same. It's just as easy to over configure DS3/DS1 Cisco HDLC trunks as Frame Relay trunks. Potentially at issue here is not Frame Relay networks as a transport but that a Cisco 7000 can not scale properly to support 120+ end-users. :-) Modern Frame Relay switches: 1) have sub-msec latency 2) can support multiple trunks at DS3+ (to include ATM) 3) are not burdened with processing any of the IP layer 3 nor routing overhead 4) because of 3 have a cost per port that is 300 to 400% less than a Cisco 7000 5) can have it's backbone shared across multiple services thereby reducing both capitalization and bandwidth expense 6) allow ISP to pass the cost savings on to customers ----------------------------------------------------------------------------- Jeff Oliveto | Phone: +1.703.760.1764 Sr.Mgr Opns Technical Services | Fax: +1.703.760.3321 Cable & Wireless, Inc | Email: joliveto(a)cwi.net 1919 Gallows Road | URL: http://www.cwi.net/ Vienna, VA 22182 | NOC: +1.800.486.9999 -----------------------------------------------------------------------------

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Re: Links on the blink - what will/should mci & sprint do?
by Sean Doran 19 Nov '95

19 Nov '95

icm-dc-3.icp.net is a 7505, as is one of its counterparts on the other side of the Atlantic. All routers in Kansas City, Seattle, Cheyenne and Atlanta are 7513s, although they are not yet up and operational. There are a largeish number of 7513s deployed in another parallel network that is engineered out of our group. No points for guessing what that's for. :) Sean.

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Links on the blink - reprise
by Gordon Cook 19 Nov '95

19 Nov '95

People are starting to tell me that the way out of smashing into the brick wall at 60 miles and hour that the Links on the Blink discussion was worrying about a week ago, is to take cascade or other frame relay switches for the national service providers backbone topology and push routers out to spoke and wheel hubs at the perimiters of the back bone where traffic sent on the backbone at the data link layer (2) can pop out and into the appropriate router for layer 3 routing to the final destination. PSI and UUNET have apparently been following this strategy with their backbones for some time. Netcom has also come on board. Its advocates say that this combination can scale and avoid the 60 mile per hour brick wall crash. Are they right? And if so why aren't sprint and MCI running in this direction and away from purely router based networks as fast as they can? If they are why are they wrong? Where does this architecture fail? If it fails. ******************************************************************** Gordon Cook, Editor & Publisher Subscript.: Individ-ascii $85 The COOK Report on Internet Non Profit. $150 431 Greenway Ave, Ewing, NJ 08618 Small Corp & Gov't $200 (609) 882-2572 Corporate $350 Internet: cook(a)cookreport.com Corporate. Site Lic $650 Newly expanded COOK Report Web Pages http://pobox.com/cook/ ********************************************************************

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Re: Links on the blink - reprise
by Paul Ferguson 19 Nov '95

19 Nov '95

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

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Re: Links on the blink - reprise
by Paul Ferguson 19 Nov '95

19 Nov '95

At 06:56 PM 11/18/95 -0600, 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. > >-alan > > Peek. A Freudian slip. :-) - paul

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