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WWW/DNS problems
by Ryan O`Connell 25 Aug '99

25 Aug '99

Hi, Not strictly a North American problem but I was wondering if anyone had seen this behaviour. We currently have two blocks of IP address space, 195.224.206/24 and 193.193.186/23. Everything works fine from 195.224.206 but from 193.193.186 there are often problems accessing web servers - either they don't respond for ages then are suddenly OK, send just the headers in response to a GET request then stop or just plain don't respond to HTTP queries at all. This appears to happen mostly with Netscape servers although I only have a few examples so far so I'm not sure. (www.real.com, www.cisco.com, www.etrade.com, www.bt.com) We also have two lines out of the building, although I've tried routing in various ways and the problem seems to follow the IP address rather than the outbound line. (IP addresses are, for the moment, tied to the line until we get BGP on the line currently serving 195.224.206/24 however I can't see how this could be an inbound line problem.) I believe this to be a DNS problem as I can't see anything else that could be causing a problem - it doesn't seem to matter what web browser is used (IE, Netscape, Lynx or even telnet) or if a web cache (Squid) is used or not. There are three reverse DNS servers in totally different locations (One on our site, one on the UK Joint Academic Network and one in Switzerland) so I don't think part of the net being unreacable from somewhere can be the problem. The only *POSSIBLE* explanation I can come up with is that the IPv6 AAAA entries for 193.in-addr.arpa are confusing some nameservers and causing this problem. I'm really grasping at straws though - does anyone have even the slightest idea what cound be going on? (Even off-list wild-guess suggestions would be appreciated.) Thanks. --- Ryan O'Connell - http://complicity.olf.co.uk:8080/ - <nemesis(a)eh.org> How do you sleep? How do you last the night and keep the dogs at bay? How do you feel when you close your eyes, and try and drift away? Does it feel any better now? Does it mean anymore When the angel of death comes knock, knocking, And banging at your door?

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FW: Tech contact for Qwest?
by Chris Flores 25 Aug '99

25 Aug '99

---Original message---- Maybe not an appropriate topic for Nanog... but... it is becoming a sad fact that the clue level of 'internet engineers' is going down. Christian -------------------- That's a fairly strong statement to make. Large telcos/ISPs tend to through "newbie" engineers into situations where a experienced or senior engineer belongs. Let's face facts - there are not enough IP engineers/technicians to fill all the needed positions. Companies need to either have more peer review or expect the "clueless" attitude toward customers. No one could expect a entry level engineer to handle complex ISP BGP issues when they barely understand VLSM/CIDR. The industry is much larger than previous years(obvious), thus more entry level engineers. CF

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Re: FIBER CUT: Between New York, NY and Philly, PA
by Sean Donelan 24 Aug '99

24 Aug '99

SEAN(a)dra.COM (Sean Donelan) writes: >There are several reports of a fiber cut in New Jersey. Several providers >have been affected. Amazingly this missed all of our circuits, even the backup circuits, so I'm getting mostly third-hand information. The fiber was some combination of Amtrack and MCI, along a railroad track in New Jersey. A backhoe was sited in the area, but I don't have a confirmed reason for the outage. Several providers reported the Sprint NAP in Pensauken was isolated. But from my experiments (LSSR is a good thing) it appears only certain providers lost their connections to Pensauken. The NAP itself is up, and working. I've never heard if anyone was ever succesfull in getting more alternate fiber into the Sprint NAP, or if your choices were still pretty limited. -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation

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FIBER CUT: Between New York, NY and Philly, PA
by Sean Donelan 24 Aug '99

24 Aug '99

I guess the rain softened the ground enough, the backhoes have come out of summer hibernation. There are several reports of a fiber cut in New Jersey. Several providers have been affected. -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation

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Re: Power outage in Vienna, Virginia and other things
by Sean Donelan 24 Aug '99

24 Aug '99

PEPCO and Virginia Power reported about 10,000 customers without power this morning due to the storms moving through the area. There are lots of Internet functions concentrated in Fairfax, Herndon, Vienna, the District of Columbia; all areas with some power outages. Overall it appears providers are doing a better job of keeping stuff running. I didn't see any 'important' services go down. Maybe ISPs have finally got it? Then again maybe not. There is a fiber cut in Herndon, VA. -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation

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Re: Training the next generation:
by Dana Hudes 24 Aug '99

24 Aug '99

Joe, I firmly believe that an undergraduate degree is essential. If you have to go part-time, then do that. Don't wimp out and take a BA. Get the BS, take the science and math courses. You might wonder what mechanics and chemistry have to do with networks or software development. Two words: Scientific Method . We need to train you, the student, to THINK. Not just that you need to think, we need to train you HOW to think. Math is more directly applicable. ----- Original Message ----- From: joe <jk(a)wnonline.net> To: Dana Hudes <dhudes(a)panix.com> Cc: <nanog(a)merit.edu> Sent: Tuesday, August 24, 1999 1:09 PM Subject: Re: Training the next generation: > > I am also interested in this, for I am fairly young and VERY interested in > building/maintaining/upgrading networks, etc. I would like to know the > very things that some of you guys complain about all the time when you try > to work with companies. Do any of you know of schools out there (besides > cisco ;P) that can offer the valued training to get people like myself > into this ever-changing field. I have taken the route of working my way > through ISP's, what other ways have some of you done? Do you think > working in a good environment and being trained onsite, being trained > onsite and going to school or just going to school would come out to be > the best idea for getting into this field. Please reply publically or > privately :> > > I apologize if this seems NON-OPERATIONAL to you, but it is to me, because > once you guys are off and gone, who will be left? > > Thanks for your time, > > joe > > ======================================================================= > joe kamm jk(a)wnonline.net > network operations > worldnet communications http://www.wnonline.net > > On Tue, 24 Aug 1999, Dana Hudes wrote: > > > Date: Tue, 24 Aug 1999 00:12:41 -0400 > > From: Dana Hudes <dhudes(a)cncdsl.com> > > Reply-To: Dana Hudes <dhudes(a)panix.com> > > To: nanog(a)merit.edu > > Subject: Training the next generation: > > > > Hi ! > > I'm teaching networking this year at CUNY Hunter College here in Manhattan. I would like your input as industry members what skills would have value to you in a new graduate computer science major (the students are seniors). > > Fall course is "Telecomputing"; the syllabus I created for the course uses Tannenbaum's _Computer Networks_ and tries to cover a range of things. Course project will likely be design and implement a bridge, possibly including source-route and certainly including spanning tree. Early on, coverage of WAN include project with PCM and such. > > A syllabus is posted at http://harmony.hudes.org/Telecomputing.html > > Students will have a broad base in a variety of networking topics. Focus on Ethernet in the LAN and PPP and ATM in the WAN. > > > > > > Spring is a "special topics" course. I've some flexibility here. I'm weighing two alternatives, and want some feedback. > > Of all possible things, the acting chair and I narrowed to two possible courses: > > 1. A course in TCP/IP. Use Comer, _Internetworking with TCP/IP_ and his syllabus from Purdue as a starting point. > > No time in this course for any physical layer or data link stuff beyond a cursory overview of Ethernet as we move at high speed to the network layer and IP forwarding. Comer's graduate course has students build a router but this is probably too much for undergraduates. Instead an OSPF implementation, including all the options (especially NSSA) . A cursory introduction to sockets programming with the course focus on routing algorithms (i.e. RIP, OSPF, and BGP4). > > Can this one course (my fall course hasn't sufficient registration to make the 2 semester sequence in networking we'd hoped; maybe next year). > > > > 2. Network application programming. Java clients, Perl and Apache server side (or perhaps Java servlets). Hunter students know C++ fairly well by their senior year; Java is an easy transition. The entire class would divide into teams with assignments that comprise various parts of the client and server portions. The project would be a turn-based simulation game (I used to play these and have a number of appropriate games with play-by-mail options, game rule design and/or game theory is not part of the course). While this won't teach them to be router engineers -- or developers, it should have some industry relevance. > > > > > > Most Hunter graduates stay in the Greater NYC metropolitan area. Given this, which of these options is better for the industry? who is in shorter supply? > > > > Prompt feedback greatly appreciated. Registrar is asking for the course description ASAP or sooner. > > > > Thanks! > > Dana Hudes > > CUNY Hunter Computer Science > > former ISP > > > >

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Re: Training the next generation:
by Dana Hudes 24 Aug '99

24 Aug '99

Surely the definitive work on IS-IS is Radia Perlman's _Interconnections_? Bridging and the spanning tree are covered there quite nicely as well. The original problem we had with IS-IS was that nobody had a CIDRized version. I think that's why. Maybe the split is earlier? I'm not sure. Huitema doesn't say anything in his book. Dana ----- Original Message ----- From: Jeff Parker <jparker(a)nexabit.com> To: Dana Hudes <dhudes(a)panix.com> Sent: Tuesday, August 24, 1999 11:23 AM Subject: RE: Training the next generation: > > > It may be a bit late to suggest this, but please keep in > > > mind for the > > > future an alternative text, entitled "An Engineering > > > Approach to Computer > > > Networking", by Keshav. > > An excellent book. A bit hard to fit your course around it, > but it gives a very different take on the subject. > > > Interesting that you put ISIS as an emerging rather than past > > protocol. > > I work on ISIS here - it is seeing new life as a routing protocol > that is much simpler, but as powerful as, OSPF. > > - jeff parker >

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Re: Training the next generation:
by Dana Hudes 24 Aug '99

24 Aug '99

Jeff, thanks for the input. Comer has a volume 3 that uses Winsock instead of BSD sockets. Stevens UNIX network programming 3rd edition added XTI, I don't know why. Market -- always a problem to have a pool of eligible students but its a hot topic. A co-requisite of our Operating Systems course, which is required, isn't too limiting -- gives a pool of about 60 students (the 30 taking the fall, the 30 taking the spring; not too many who took it last spring will be around next spring). I can't take more than 30, would rather have 20. Hunter is big on C++ but I found out that they don't teach methodology despite calling the courses software engineering. Its really the same course as it was when they used Pascal, only now they use C++. If I get up in front of class and start drawing use-case diagrams, nobody will know what I'm talking about. so much for a class-wide project in the large. I'm going for the Comer vol. 1 course, plus sockets. Thanks again, Dana ----- Original Message ----- From: Jeff Parker <jparker(a)nexabit.com> To: Dana Hudes <dhudes(a)panix.com> Sent: Tuesday, August 24, 1999 9:47 AM Subject: RE: Training the next generation: > Dana - > I teach a course here at the Harvard Extension school > similar in aims to your 2nd course here. I've been using > Steven's Unix Network Programming plus lecture notes that cover > some of the Internet Protocols (ARP, BootP, ... RPC, NFS, AFS, ...) > > I don't cover much about TCP - other than a lecture that > includes MTU discovery and Slow Start. Some of this is that our > first semester course covers sliding window, etc. However, ours > is a very market-driven course (that is, I don't have a natural market, > so I can't scare folks off with prereqs) I cannot assume too much. > > Lately, I've been finding that our students don't know > enough about Unix and Unix System Programming to deal with Stevens: > I've switch the language from C to Java, and I'm using a Java > text to teach sockets programming, as well as using Stevens > TCP/IP Illustrated to teach the protocols. > > The project has always been a client/server system: we > start with a simple name server with 3 operations: Insert, > Delete, and GetNext, and deal with issues such as packet loss > (I give them a "flakey sendto" that drops 2 packets out of 5, > and introduces duplicate packets) and transactions (to deal > with a "rename" (delete and insert) encountering a getNet walk. > > Depending upon the background, the setup (how does their > bridge send/rcv packets, what they have to observe traffic - sniffer?) > I would think that your bridge assignment would be challenging. > > I'd be interested to chat about your course: here is a link > to last semester's website. > > http://www.fas.harvard.edu/~adm119/cs258/ > > - jeff parker > > > 2. Network application programming. Java clients, Perl and > > Apache server side (or perhaps Java servlets). Hunter > > students know C++ fairly well by their senior year; Java is > > an easy transition. The entire class would divide into teams > > with assignments that comprise various parts of the client > > and server portions. The project would be a turn-based > > simulation game (I used to play these and have a number of > > appropriate games with play-by-mail options, game rule design > > and/or game theory is not part of the course). While this > > won't teach them to be router engineers -- or developers, it > > should have some industry relevance. > > > > > > Most Hunter graduates stay in the Greater NYC metropolitan > > area. Given this, which of these options is better for the > > industry? who is in shorter supply? > > > > Prompt feedback greatly appreciated. Registrar is asking for > > the course description ASAP or sooner. > > > > Thanks! > > Dana Hudes > > CUNY Hunter Computer Science > > former ISP > > >

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Re: Training the next generation:
by Dana Hudes 24 Aug '99

24 Aug '99

Dan, thanks for the input. IP routing research is a subject near and dear to my heart. I have wanted, for a long time, to do some work on traffic engineering using flow optimization algorithms from the literature applied to BGP policy. Do you think this is sufficiently interesting and useful to InterNAP that they could come up with funding ? In our business not too many PhDs with operational experience so a fellow with the operational experience and a Master's (me) might suffice. As for the coursework: ----- Original Message ----- From: Dan Cohn <dan(a)internap.com> To: Dana Hudes <dhudes(a)panix.com> Sent: Tuesday, August 24, 1999 2:02 AM Subject: Re: Training the next generation: > > > I think you are right on approaching the computer networking industry. We > are always short talented engineers, and spend a great deal of time > seeking the few that are available. > I was a 1st line manager with hiring responsibility for 2 years; while working for Bay Networks Consulting I interviewed candidates there as well. Very hard to find anyone with a clue and analytical skills. So I'm out to make some. > > Fall course is "Telecomputing"; the syllabus I created for the course > > uses Tannenbaum's _Computer Networks_ and tries to cover a range of things. > > It may be a bit late to suggest this, but please keep in mind for the > future an alternative text, entitled "An Engineering Approach to Computer > Networking", by Keshav. Interesting. I shall have to quickly check it out. >While Tannenbaum has long been recognized as a > solid foundations book, Keshav's material is much less esoteric, more up > to date, and replaces complex statistical mathematics of little use to the > common network engineer You think Tannenbaum is bad, look at Grodzinsky. I about fell off my chair when their network simulation exercise involves MathCAD! The introductory exercise involves a bit of FFT using Maple. I know neither of these programs, but I've seen that they are now used in undergraduate mathematics education extensively (when I took calculus and D.E. etc. it was the same as always had been -- lecture + recitation + homework with pencil and paper). Nonetheless Grodzinsky has some good projects for students to implement various network aspects so I chose it as 2nd text for the class. >with practical examples from real-world production > networks. I believe you will find the Keshav course material is as > comprehensive as the Tannenbaum book, but much more fun to read. Sounds great. Wish I'd had this information four weeks ago when I chose the book for the course. Class starts Monday. > > >Course project will likely be design and implement a bridge, possibly > >including source-route and certainly including spanning tree. > > Unfortunately, the term 'bridge' has not been used actively in computer > networking for a number of years, and when it has it generally refers to > either a concept or support for a legacy environment. Spanning tree is a > very important protocol, and can form the conceptual base for many > protocols which followed it, but may not deserve more than a few days > coverage, especially in an introductory class designed to prepare students > for current and future technologies. 'design and implement a bridge' is > slightly troubling to me, as bridges are fairly passive devices which are > generally avoided in current practice.. Unless you intend to have the > students actually write an implementation of spanning tree, this task > should involve little more than plugging two devices into a hub. When I say build a bridge, I mean write one in software. Complete with spanning tree implementation, BPDUs etc. A LAN switch acts like a multiport bridge. It just has hardware assist to move frames around. BTW, I build bridging in to use the facility in a WAN switch rather than let it do IP forwarding. Remote city dialup (multiple chassis, each 2xDS-3 dial trunks) comes to ATM switch Ethernet interface and is bridged to remote router which has an ATM PVC configured for ATM Half Bridge. No spanning tree. Only the remote ATM switch knows its bridging, the central switch just pushes the ATM cells to the router. > > Source route bridging, on the other hand, while slightly more complex, is > also considered a legacy protocol, and efforts are being made wherever > possible to replace SRB networks with scalable, routable alternatives. SNA will never die completely. Wish it would. Keeps coming up. > Again, in my own teachings, this is a topic which usually gets a few hours > in passing, as a legacy protocol which hopefully no student will > encounter.. and when they do encounter it, it will most certainly be for > the purpose of finding a migration strategy to something more scalable, be > it SNA over DLSW, or a full migration to IP. I agree that SRB first of all is an extra complexity students don't need and is of lesser importance. I will introduce the real nasty, translational bridging real quick and explain why we don't do such things. > > > Early on, coverage of WAN include project with PCM and such. > > A syllabus is posted at http://harmony.hudes.org/Telecomputing.html > > Students will have a broad base in a variety of networking topics. > > Focus on Ethernet in the LAN and PPP and ATM in the WAN. > > Excellent material. Be mindful of the order at which you bring in > discussion of ATM, as it does not strictly conform to the OSI model, which > should be well understood before ATM is discussed, IMO. A good segue into > ATM is Frame Relay, which is still rather prolific in the industry. Tannenbaum doesn't try to cover ATM all at once. He splits up the coverage according to the OSI layers. Notably, in this 3rd edition layers 5 and 6 are just about gone. That's fine for router engineers but ironically things like XBR are presentation layer and important to client/server programmers. I suppose one can shove XBR into application layer. > > > Spring is a "special topics" course. I've some flexibility here. I'm weighing > > two alternatives, and want some feedback. Of all possible things, the > > acting chair and I narrowed to two possible courses: > > 1. A course in TCP/IP. Use Comer, _Internetworking with TCP/IP_ and his > > syllabus from Purdue as a starting point. No time in this course for any > > physical layer or data link stuff beyond a cursory overview of Ethernet > > as we move at high speed to the network layer and IP forwarding. > > This is a good text, and you are likely correct about the timeframe. I > encourage you to also delve into some projects from Network Programming by > Stevens, if your students are expected to have a certain degree of > competency with programming for Unix in C, as this tends to really cement > the learning process. Good projects include having students write an > implementation of nslookup, talk, or ftp from scratch, using the RFCs as a > resource. Interesting project idea instead of having them work on routing protocols. But, source to all the things you mention is readily available. OSPF source isn't quite so easy to find. > > > Comer's graduate course has students build a router but this is probably > > too much for undergraduates. > > Quite true.. routers are complex things. This is a project for people who > not only are already extremely comfortable with the network layer > protocols they are implementing towards, but also who have a good grasp on > multiprocessing, have a fairly good understanding of routing protocols, > and have significant experience writing network code. Even a simple router is pretty complicated. But if I use UNIX (or NT) as a base, we skip ahead to routing protocols and don't have to implement IP forwarding. Multiprocessing they get from the OS course. > > >Instead an OSPF implementation, including all the options (especially > > NSSA) . A cursory introduction to sockets programming with the course > > focus on routing algorithms (i.e. RIP, OSPF, and BGP4). > > Can this one course (my fall course hasn't sufficient registration > > to make the 2 semester sequence in networking we'd hoped; maybe next > > year). > > Please, please include ISIS and some discussion of emerging multicast > standards in this discussion. Students familiar with emerging dominant > technologies are much more marketable and useful than those who know what > everyone else has already learned from experience. Much too little > emphasis is placed on ISIS and multicast considering the likelihood for > their relative abundance in the future. Interesting that you put ISIS as an emerging rather than past protocol. Multicast is on my agenda somewhere. They're in good shape to deal with such things given the heavy data structures background they bring to the course (discrete structures is 1 semester, then 3 semesters of algorithms + data structures; all in C++). Certainly I shall include it somewhere in the Telecomputing course; the spring also should have something about it but not sure yet where and how. > > > > > 2. Network application programming. Java clients, Perl and Apache > > server side (or perhaps Java servlets). Hunter students know C++ fairly > > well by their senior year; Java is an easy transition. The entire class > > would divide into teams with assignments that comprise various parts of > > the client and server portions. The project would be a turn-based > > simulation game (I used to play these and have a number of appropriate > > games with play-by-mail options, game rule design and/or game theory is > > not part of the course). While this won't teach them to be router > > engineers -- or developers, it should have some industry relevance. > > > > By the time a student reaches their senior year, they should be very well > capable of writing the entire gaming system on their own, including client > and server components. Systems like this generally do not involve very > much network code, and dividing it up too much would be a shame. Please > also consider having your students do some of this work with CORBA, and > implement different components in a few different languages. Again, make > your students useful because they have done what other people are starting > to do or thinking about doing, not because they have done a little bit of > what everyone in the industry already knows very well how to do. > The gaming system is bigger than you think. Consider GUI client. There is the question of the application protocol for communicating moves etc. . The trouble is that there is a considerable amount of non-network related design and implementation (e.g. the economic system, combat system etc.). It really is a fine line between such a project and distributed systems. After all, the user should not see the network in such a game. > > Most Hunter graduates stay in the Greater NYC metropolitan area. > >Given this, which of these options is better for the industry? > > Presently, people who understand network engineering from a routing, > design, and troubleshooting point of view are in extremely high demand. > People who can write some network enabled code are in relatively small > demand. Salaries for the former in NYC start at abt $70k, salaries for > the latter start at $35-40k. Concentrate on IP routing, emerging > technologies in IP routing, and coding to solidify that understanding, is > my advice. Thanks. But, this isn't an operations course. Rather, to prepare them to work for Lucent/Ascend, cisco, Bay, etc. in building the stable products network architects require. Network architecture, properly done, involves traffic engineering. Where exactly do you want the traffic to flow. Rather than optimize at the AS level, a computer can create a policy to optimize at the prefix level (you are, after all, already doing per-prefix filtering if you're careful). Regardless of the goals and constraints. So many of the folks configuring routers *can't program*. Not a bit. They're former electrical engineers. In fact, I've had agencies tell me I'm not qualified for the position of network engineer because my degrees are computer science not electrical engineering. Who do they think builds routers, EEs alone? Eek. Musicians write better code than most EEs I've seen. > > Feel free to call on me if I can be of any assistance in your planning or > during the instruction of your course, Well, any of you folks who happen to have any old (or new, you manufacturer folks here's a chance to get your new toys in front of the next generation) network equipment you can donate or loan to Hunter to build up our network student lab we would appreciate it. I don't take such directly, but please contact me if you can help and I will make the introductions all around to make it happen. Thanks very much to all for the feedback. It sounds like both my courses are needed but the IP course is better. That's somewhat expected from this crowd. Dana Hudes > > Thanks, > > Daniel Cohn > Senior Network Development Engineer > InterNAP Network Services > Seattle, WA > >

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Re: Power outage in Vienna, Virginia and other things
by Sean Donelan 24 Aug '99

24 Aug '99

SEAN(a)dra.COM (Sean Donelan) writes: >While checking on Vienna, I also found I had problems reaching sites >in Boston, MA. Both Tufts University and Boston University are off-net. >I haven't heard of anything happening in the Boston area. I know Tufts >switch providers, but I don't know about BU. So the information in the >RADB may not give good information for reaching the correct upstream >provider. The sites have come back up, and it appears the former nearnet lost more customers than I knew about. Because the new provider doesn't include information in an public RADB-like database, I didn't realize all the sites went through the same place. I was looking for and asking the wrong provider. UUNET had announced on their maintenance page they are replacing routers in Boston, MA this morning. The router maintenance affected the sites I was using to check for problems: computerworld.com, tufts.edu, and bu.edu. I guess its time to look for new beacons. -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation

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