Re: OSPF WG Charter Proposal
"Manral, Vishwas" <VishwasM@NETPLANE.COM> Thu, 07 November 2002 17:27 UTC
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Date: Thu, 07 Nov 2002 12:31:24 -0500
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From: "Manral, Vishwas" <VishwasM@NETPLANE.COM>
Subject: Re: OSPF WG Charter Proposal
To: OSPF@DISCUSS.MICROSOFT.COM
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Hi Dave/Tony/folks, Thanks a lot for the comments. I agree a large part of the draft covers implementation specific stuff like the need for pacing LS updates/reducing the rate of flooding etc. An implementation not doing that could cause problems as Jerry mentioned in his earlier mail, and as Tony mentioned, is not learned the easy way. We did get the comment from Dave(on the prepublished version of the draft) to reduce implementation specific stuff, which we have to the minimum. I however do think we can give implementation recommendations without affecting a good implementation (eg I do not think saying pacing needs to be done hampers a good implementation, though telling the mechanism to do it does, which i think is not implementation specific anymore but a necessary requirement) Besides in case of extreme congestion, we did figure out the only way to bring adjacencies up is signal to the neighbor to slow the rate of flooding further(for which we are using signalling) besides the other way to selectively brining up adjacencies at a time. This I think is the only significant change which requires bits on the wire to change. Our aim is to minimize changes to normal processing/code, while also getting over the problem gracefully when it occurs and not having to go down for days at a time. We also need to reduce the number of configureables, which we do intend to minimize further. Besides I do think from my readings that these problems are more common, than I had initially guessed, though it does not always cause a network collapse. Though Tony I m not sure how ISIS 0-63 bits would add to recommendations of implementation;-) Thanks again, Vishwas -----Original Message----- From: Tony Przygienda [mailto:prz@XEBEO.COM] Sent: Thursday, November 07, 2002 9:47 PM To: OSPF@DISCUSS.MICROSOFT.COM Subject: Re: OSPF WG Charter Proposal Ash, Gerald R (Jerry), ALASO wrote: >Dave, > >>>Such failures are not the fault of the service provider >>>operation or the vendor/equipment implementation. They are >>>due to shortcomings in the link-state protocols themselves -- >>>thus the need for the enhancements proposed in the draft. >>> > >>I strongly disagree with this statement. While the design of the >>protocols can make it challenging, there is ample room in >>implementation to provide stable and scalable networks. >> >>When a network collapses, the fault lies at the feet of the >>implementers. In every case I've seen (too many), the collapse was >>inevitable sooner or later, due to naive design choices in software, >>but at the same time was quite nonlinear in its onset (making any >>predictive or self-monitoring approach pretty hopeless.) >> >>There are some things that would make the job easier, at the cost >>of additional complexity, but pointing at network collapses >>and blaming the protocols is disingenuous. >> > >I think you should review the ample evidence presented in http://www.ietf.org/internet-drafts/draft-ash-manral-ospf-congestion-control -00.txt that the protocols need to be enhanced to better respond to congestion collapse: > >- Section 2: documented failures and their root-cause analysis, across multiple service provider networks (also review the cited references) >- Appendix B: vendor analysis of a realistic failure scenario similar to one experienced as discussed in Section 2 (perhaps you would like to provide your own analysis of this scenario based on your OSPF implementation) >- Appendix C: simulation analysis of protocol performance (other I-D's being discussed provide analysis of proposed protocol extensions) > >To say that network collapse in *every* case is due to *naive design choices* ignores the evidence/analysis presented. Based on the evidence/analysis, there is clearly room for the protocols to be improved to the point where networks *never* go down for hours or days at a time (drawing unwanted headlines & business impact). > >Jerry > Jerry, most of the things you say in your document (which is actually pretty good) has been known to people like Dave and other old-time implementors since years and avoiding exactly those things by smart implementation techniques was what was differentiating the have from the have-nots. I remember myself learning some of those things by hard experience and some by looking at old-hands code ;-) [Albeit I remember also picking up a lot of smart control protocol ideas from your RTNR work]. I do not think that Dave is putting down what you say, rather (and I commit the stupidity to interpret his words by my own beliefs) that what your document says are mostly _implementation_ issues, not _standardization_ and therefore it is not a very wise idea to add them to the charter of a _standards_ group. Good protocol specs are _not_ implementation cookbooks, they are documents governing bits on the wires in such a way that two people implementing things in vastly different ways can still talk to each other. Recommendations of implementation techniques prove long-term inherently dangerous (like Joel pointed out, at a certain point in time adding more code to an implementation introduces more bugs than the performance gain is worth) or utterly ridiculous (look at ISIS 0-63 metric to make SPF real fast, it lead to quite bad contortions). thanks -- tony
- OSPF WG Charter Proposal Rohit Dube
- Re: OSPF WG Charter Proposal Naidu, Venkata
- Re: OSPF WG Charter Proposal Rohit Dube
- Re: OSPF WG Charter Proposal Naidu, Venkata
- Re: OSPF WG Charter Proposal Acee Lindem
- Re: OSPF WG Charter Proposal Manral, Vishwas
- Re: OSPF WG Charter Proposal Mukesh Gupta
- Re: OSPF WG Charter Proposal Rohit Dube
- Re: OSPF WG Charter Proposal Acee Lindem
- Re: FW: OSPF WG Charter Proposal Rohit Dube
- Re: FW: OSPF WG Charter Proposal Don Goodspeed
- Re: FW: OSPF WG Charter Proposal Naidu, Venkata
- Re: FW: OSPF WG Charter Proposal Rohit Dube
- Re: OSPF WG Charter Proposal Manral, Vishwas
- Re: FW: OSPF WG Charter Proposal Manral, Vishwas
- Re: FW: OSPF WG Charter Proposal Jeff Parker
- Re: FW: OSPF WG Charter Proposal Joyal, Daniel R (Daniel)
- Re: OSPF WG Charter Proposal Ash, Gerald R (Jerry), ALASO
- Re: OSPF WG Charter Proposal Manohar Naidu Ellanti
- Re: OSPF WG Charter Proposal Dave Katz
- Re: OSPF WG Charter Proposal Ash, Gerald R (Jerry), ALASO
- Re: OSPF WG Charter Proposal Rohit Dube
- Re: OSPF WG Charter Proposal Joel M. Halpern
- Re: OSPF WG Charter Proposal Tony Przygienda
- Re: OSPF WG Charter Proposal John Drake
- Re: OSPF WG Charter Proposal Jeff Parker
- Re: OSPF WG Charter Proposal Manral, Vishwas
- Re: OSPF WG Charter Proposal Manral, Vishwas
- Re: OSPF WG Charter Proposal Tony Przygienda
- Re: OSPF WG Charter Proposal Ash, Gerald R (Jerry), ALASO
- Re: OSPF WG Charter Proposal Rohit Dube
- Re: OSPF WG Charter Proposal Ash, Gerald R (Jerry), ALASO
- Re: OSPF WG Charter Proposal Dave Katz
- Re: OSPF WG Charter Proposal Manohar Naidu Ellanti
- Re: OSPF WG Charter Proposal Dave Katz
- Re: OSPF WG Charter Proposal Choudhury, Gagan L, ALASO
- Re: OSPF WG Charter Proposal Manral, Vishwas
- Re: OSPF WG Charter Proposal Dave Katz
- Re: OSPF WG Charter Proposal Manral, Vishwas
- Re: OSPF WG Charter Proposal Tony Przygienda
- Re: OSPF WG Charter Proposal Rohit Dube
- Re: OSPF WG Charter Proposal Acee Lindem
- Re: OSPF WG Charter Proposal Choudhury, Gagan L, ALASO
- Re: OSPF WG Charter Proposal Dennis Ferguson
- Re: OSPF WG Charter Proposal Dave Katz
- Re: OSPF WG Charter Proposal Alex Zinin
- Re: OSPF WG Charter Proposal Choudhury, Gagan L, ALASO