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Re: Flapping /16 prefix, why?
by Rob Liebschutz 21 Feb '97

21 Feb '97

> Sorry for littering NANOG with this email, but I'm hoping for a little > education on this matter from some of the larger National Service > Providers. > > This morning we had a customer call in concerning a network hole. > Upon investigation, I found the following.. > > BGP routing table entry for 166.82.0.0/16, version 541808 > Paths: (1 available, best #1, advertised over IBGP, EBGP) > 1793 1239 1790 3505 3505 > 144.228.159.17 from 144.228.159.17 (144.228.159.1) > Origin IGP, metric 0, valid, external, best > Community: 1 > Dampinfo: penalty 656, flapped 18 times in 02:19:29 > > Two immediate things came to mind here. > > 1. This is a /16 that is flapping. > 2. The end user is using AS path prepending for some reason. > > With these two facts in mind, the following questions arise. > > Anchoring or tying down of a route with a static route to null seems > to be a very basic idea (far more basic that AS path prepending), so > why isn't this route tied down? If their is a link flapping somewhere between the border of the AS where the route is announced and your network, your going to see flapping regardless of weather the route is tied down. I previously though that tying down my routes was the best thing. This may be so for the heath of the Internet, but I've had substantial problems with the LAN interface on one of my routers. Everytime the LAN interface goes down, my routes would get blackholed. So the Health of the Internet may be better if I tie down my route, but, my customers will be happier if a failure on my LAN interface causes my traffic to be routed over another NAP instead of blackholed. On another of my routers, on which I've never had problems with the LAN interface, I do tie the route down. > > I only see one route to this prefix, why are they prepending? (I admit > that only the user of this prefix can answer this question, and I also > admit that with 53 flaps on the books so far, the other provider may > be dampening the route for us *thank you*) > > Finally, does Sprint not apply *any* dampening to customer routes? > > > > My cat is long dead (10 years at least), so it's safe from my curiosity. > > Chris A. Icide > Nap.Net, L.L.C. > >

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Flapping /16 prefix, why?
by Chris A. Icide 21 Feb '97

21 Feb '97

Sorry for littering NANOG with this email, but I'm hoping for a little education on this matter from some of the larger National Service Providers. This morning we had a customer call in concerning a network hole. Upon investigation, I found the following.. BGP routing table entry for 166.82.0.0/16, version 541808 Paths: (1 available, best #1, advertised over IBGP, EBGP) 1793 1239 1790 3505 3505 144.228.159.17 from 144.228.159.17 (144.228.159.1) Origin IGP, metric 0, valid, external, best Community: 1 Dampinfo: penalty 656, flapped 18 times in 02:19:29 Two immediate things came to mind here. 1. This is a /16 that is flapping. 2. The end user is using AS path prepending for some reason. With these two facts in mind, the following questions arise. Anchoring or tying down of a route with a static route to null seems to be a very basic idea (far more basic that AS path prepending), so why isn't this route tied down? I only see one route to this prefix, why are they prepending? (I admit that only the user of this prefix can answer this question, and I also admit that with 53 flaps on the books so far, the other provider may be dampening the route for us *thank you*) Finally, does Sprint not apply *any* dampening to customer routes? My cat is long dead (10 years at least), so it's safe from my curiosity. Chris A. Icide Nap.Net, L.L.C.

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Re: policy routing and netflow (was Re: karl and paul, expostulating )
by Brett D. Watson 21 Feb '97

21 Feb '97

well *i* dind't think it was a bad name, i think we were getting into a semantics battle. (access-list filtering vs. policy route map filtering). if i come up with a better name thought, i'll let you know :) -brett > > they call source based routing > "policy routing". bad choice of names i guess but that's what they > call it. > > My most profuse apologies. Just so I don't make the same mistake again, > what should I have called it? > > ;-) > > Tony >

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Re: BGP4 tutorial slides
by bajaj＠bellcore.com 21 Feb '97

21 Feb '97

> > > > The BGP Tutorial Slides are now on line at this URL: > > > http://www.academ.com/nanog/feb1997/BGPTutorial/index.htm > > Are the slides also available as a single ftp-able file somewhere? Thanks. Shikhar Bajaj

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Re: BGP4 tutorial slides
by Paul Ferguson 21 Feb '97

21 Feb '97

Yes, that obviously needs to be corrected. :-) - paul At 07:59 AM 2/21/97 +0100, sthaug(a)nethelp.no wrote: >> The BGP Tutorial Slides are now on line at this URL: >> http://www.academ.com/nanog/feb1997/BGPTutorial/index.htm > >I see Paul's last name has become "Furguson" on that page :-) > >Steinar Haug, Nethelp consulting, sthaug(a)nethelp.no > >

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Re: karl and paul, expostulating
by Mark Borchers 21 Feb '97

21 Feb '97

Paul A Vixie wrote: > > I don't have a hair trigger on this gun -- it takes quite a while for me to > decide that someone can't/won't come around on their own. Couldn't you make an exception?.... Associated Press PHILADELPHIA It's about to get much easier for advertisers to send junk e-mail on the Internet.Cyber Promotions Inc. will launch the first bulk e-mail friendly Internet provider in the nation on March 17. It will allow computer users to send millions of commercial ads also known as spam for a single monthly fee. http://www.desnews.com/newbiz/ia0lb0tx.htm

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policy routing and netflow (was Re: karl and paul, expostulating )
by Brett D. Watson 21 Feb '97

21 Feb '97

> On Feb 20, 1997, Brett D. Watson wrote: > > > > doesn't matter. in production ios, policy routing (source based > > routing) is process switched. there is code in the works to make it > > fast switched. but there is a bug wherein if you do policy routing, > > and you enable flow or optimum switching on the interface you're > > doing pr on , it disables the policy routing. > > > > that bug may be fixed now but in any case enabling flow switching > > will *not* speed up policy routing. and if you're exporting the flow > > stats, you lose anywhere from 50kpps to 100Kpps of speed. > > I have news for you; this isn't policy routing! you better tell cisoc that then :) they call source based routing "policy routing". bad choice of names i guess but that's what they call it. it's an inbound route map applied to an interface and you look at the *source* address of the packet, then use various "set" clauses based on that address. > We aren't re-writting > any source or destination addresses (which is what policy routing > does). i have news for you, policy routing has nothing to do with re-writing source or destination addresses. > We're just filtering based on source and destination > parameters (such as address, protocol, port, etc). if you're filtering based on source-anything, and you're using a cisco, i'd like to know how you're doing it without policy route-maps. please see: www.cisco.com/warp/public/732/Tech/plicy_wp.htm i didn't imply that you were doing anything. i may have misundestood justin but i thought he was implying that netflow switching would increase the switching speed of policy based routing, as cisco calls it, and it does not. that's all i was getting at. > Flow switching works very effectively (at least as of IOS 11.1.9). yes it does. i never said it didn't work well. who's mail were you reading anyway? -brett

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Re: BGP4 tutorial slides
by sob＠academ.com 21 Feb '97

21 Feb '97

> > The BGP Tutorial Slides are now on line at this URL: > > http://www.academ.com/nanog/feb1997/BGPTutorial/index.htm > > I see Paul's last name has become "Furguson" on that page :-) > > Steinar Haug, Nethelp consulting, sthaug(a)nethelp.no Fixed. Also, the index page is now up and will be filled in over the course of the next couple of weeks. http://www.academ.com/nanog/feb1997 The welcome stuff is up. -- 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: BGP4 tutorial slides
by sthaug＠nethelp.no 21 Feb '97

21 Feb '97

> The BGP Tutorial Slides are now on line at this URL: > http://www.academ.com/nanog/feb1997/BGPTutorial/index.htm I see Paul's last name has become "Furguson" on that page :-) Steinar Haug, Nethelp consulting, sthaug(a)nethelp.no

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Re: BGP4 tutorial slides
by sob＠academ.com 21 Feb '97

21 Feb '97

The BGP Tutorial Slides are now on line at this URL: http://www.academ.com/nanog/feb1997/BGPTutorial/index.htm Enjoy. -- 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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