April 1996 - Test - lists.nanog.org

max. prefix length
by algold＠lambda.lncc.br 26 Apr '96

26 Apr '96

Sorry for the newbie question: Is there a consensus on the maximum network prefix length that can be accepted for announcement between full-routing BGp speakers ? -- ----------------------------------------------------------------------------- | Alexandre Leib Grojsgold | tel: + 55 21 542-2746 | | LABORATORIO NACIONAL DE COMPUTACAO CIENTIFICA | fax: + 55 21 295-8499 | | 22.290 Rio de Janeiro - RJ - Brasil | | -----------------------------------------------------------------------------

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Re: max. prefix length
by Paul Ferguson 26 Apr '96

26 Apr '96

At 05:31 PM 4/26/96 -0400, Sean Doran wrote: > >Technically, anything between a /0 (which, Paul, would be >the minimum length ;> ) and a /32 is supported by BGP4. > Can I be often confused dyslexic and. :-) - paul

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Re: max. prefix length
by Sean Doran 26 Apr '96

26 Apr '96

-----BEGIN PGP SIGNED MESSAGE----- > >Is there a consensus on the maximum network prefix length that can be accepted > >for announcement between full-routing BGp speakers ? > > I would think it would be a /1, although I admit I've not actually > tried it. :-) Is there a consensus on what _can_ be accepted? Well, probably not. Depending on where you're connected and what you're trying to accomplish, there may be practical limits to the usefulness of certain prefix lengths. Technically, anything between a /0 (which, Paul, would be the minimum length ;> ) and a /32 is supported by BGP4. Most large networks won't accept a /0 (which is the ultimate default); some of our peers filter out anything shorter than a /8. A number of large networks, including Sprint and MCI, filter out anything longer than 24 bits. I suspect that if someone started announcing significant numbers of /32s (host routes), we would see more such filtering. A number of networks do no filtering at all. Sprint currently filters announcements from its non-customers as follows: in the classical "A" space: accept nothing longer than /8 [*] in the classical "B" space: accept nothing longer than /16 in newer "C" space: in 206/8: accept nothing longer than /19 in 207/8 - 223/8: accept nothing longer than /18 [*] in 194/8: accept nothing longer than /18 [*] (The things tagged with [*] are "soft"-ish policies. When technical ways emerge that will let us relax our filters to a degree (in the "C" space, to come more in-line with the registries' windowed allocation schemes; in "A" space, to allow very large subnets, like /12s in the "A" space perhaps), then we may do so. One of the things under test now is progressive dampening penalties across the entire address space. The idea is that the longer an unstable prefix happens to be, the longer it will be suppressed when it regains stability. Right now, in the initial testing, we're penalizing /24s such that if three flaps occur in 45 minutes, we suppress the unstable /24 for three hours after it becomes stable again. All other prefixes, including /23s, are suppressed for much less time (the shorter the prefix, the less "aggressively" dampened). The general idea is to make it worthwhile for people to consider doing aggregation even as simple as coalescing neighbouring /24s into a /23, or to renumber into an more aggregatable block, unless your announcement is _very_ stable.) Sean. P.S.: There are a depressing number of prefixes (some 25 or so, ALL of them /24s) that behave like these two. Please, folks, run BGP dampening code on your routers. SL-MAE-E>sh ip bgp 198.68.161.0 BGP routing table entry for 198.68.161.0/24, version 138091 Paths: (3 available, best #3) 3830 4388 3703, (suppressed due to dampening) 192.41.177.170 from 192.41.177.170 (204.157.228.1) Origin incomplete, metric 1, localpref 90, valid, external Dampinfo: penalty 6296, flapped 958 times in 17:20:54, reuse in 04:14:00 SL-MAE-E>sh ip bgp 198.184.184.0 BGP routing table entry for 198.184.184.0/24, version 737871 Paths: (1 available, no best path, advertised over EBGP) 690 1321 2386, (suppressed due to dampening) 192.41.177.140 from 192.41.177.140 (140.222.147.62) Origin incomplete, metric 1, localpref 90, valid, external Dampinfo: penalty 6288, flapped 405 times in 08:08:01, reuse in 04:14:00 -----BEGIN PGP SIGNATURE----- Version: 2.6.2 Comment: PGP Public Key in ftp://ftp.sprintlink.net/engineer/smd/pgpkey iQCVAwUBMYFAtESWYarrFs6xAQEBIAP/ejJNi7QOv+rUbnmcAVloFM40DJpsjg+P Fw8xDof+4jjVO4Iv7J5V/uqgzKdY1Xt/oi8L+mLH3TeF4o5D/Go274xP+rUfiUcU NAahWl/lt0RMSVYQENQ8nVXOTBwGsJ98F6gSWbVm9SYiGq5fiIG4Y0H7l8FT4b9v XibRTwlHtl0= =VdrR -----END PGP SIGNATURE-----

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Re: max. prefix length
by Paul Ferguson 26 Apr '96

26 Apr '96

At 04:06 PM 4/26/96 -0300, Alexandre Leib Grojsgold wrote: >Sorry for the newbie question: > > >Is there a consensus on the maximum network prefix length that can be accepted >for announcement between full-routing BGp speakers ? > > I would think it would be a /1, although I admit I've not actually tried it. :-) - paul > >-- >----------------------------------------------------------------------------- >| Alexandre Leib Grojsgold | tel: + 55 21 542-2746 | >| LABORATORIO NACIONAL DE COMPUTACAO CIENTIFICA | fax: + 55 21 295-8499 | >| 22.290 Rio de Janeiro - RJ - Brasil | | >----------------------------------------------------------------------------- >

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Re: Inter-exchange media types
by Paul Ferguson 25 Apr '96

25 Apr '96

At 02:23 PM 4/25/96 -0400, ipasha(a)sprintlink.net wrote: > >On Thu, 25 Apr 1996, Jeremy Porter wrote: > >> >> I know of plans for at least 2 exchanges that will use 100baseTx >> as a connection option. The only real problem is >> the backplane limit of boxes that switch 100baseTX, >> (Cisco Cat 5000, 1.2gbps). This is only slightly >> better than the Dec Gigaswitch limit of 800mbps. > > > DEC Gigaswitch is actually a 3.6Gb/s switch > > Ye olde trick aggregate bandwidth answer. I know that one. ;-) - paul > > > --Ismat > > > >

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Re: NAVYJOBS.COM
by Paul Ferguson 25 Apr '96

25 Apr '96

Or, to: domain-policy(a)internic.net. Please. - paul At 07:13 AM 4/25/96 -0700, bmanning(a)isi.edu wrote: > >Perhaps this is because nanog is not the place where this is being discussed. >Have you considered moving your TLD concerns/issues to the newdom list? > >-- >--bill > >

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Re: NAVYJOBS.COM
by avg＠postman.ncube.com 25 Apr '96

25 Apr '96

The problem of "obvious" solution of somebody charging a hell lot of money for smaller names is that someone got to _receive_ that money. Now try to answer who's going to get it? There's already noise that InterNIC is making too much with the cost-recovery-based registration fees. --vadim

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Wyndham Bristol Hotel
by Pam Ciesla 25 Apr '96

25 Apr '96

When making reservations at this hotel for the NANOG Meeting please use the hotel's direct phone number 202-955-6400. The 800 number is not furnished with meeting info. Please call before 6:00PM or you are automaticly switched to the 800 number. Kind of a catch 22. pam

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Inter-exchange media types
by Jon 'tex' Boone 25 Apr '96

25 Apr '96

Folks, I know that many of the Inter-exchange points are using FDDI and switched FDDI for inter-exchange in lieu (or anticipation) of ATM. I am wondering if anyone has considered using switched 100baseFx or similar technology for an inter-exchange. Given the relative newness of these interfaces on high-end routers I would not be suprised to hear that no one is using them right now. But has anyone looked into using them? Is there a good reason to prefer switched FDDI over 100baseFx (which can do full-duplex 100 Mb/s switched)? <tex(a)isc.upenn.edu>

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Re: Inter-exchange media types
by Wolfgang Henke 25 Apr '96

25 Apr '96

The problem for the major exchanges may soon be what to do when the gigaswitch runs out of bandwidth. It seems to suggest more exchange points; like for example the recent interest in new regional packet exchanges in California and Utah. When large 'tier 1' providers run into bottleneck problems, do we have to rely more on the intermediate and smaller ones to connect us? Wolfgang

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