February 2003 - Test - lists.nanog.org

OT: 111 8th Ave. Parking
by Charles Sprickman 09 Feb '03

09 Feb '03

Hi, Any advice? Any secret spots? I've been there exactly once and I didn't see any good spots. Looking to go in this weekend, but would love hints for weekday travel as well. Thanks, Charles -- Charles Sprickman spork(a)inch.com

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Re: Cascading Failures Could Crash the Global Internet
by sgorman1＠gmu.edu 08 Feb '03

08 Feb '03

Ya - that pretty much sums it up - interesting model dubious application in reality. Homogenous, in this context, does not mean similar platform connectivity, but nodes with same degree connecting to each other. It is more likely for a node with ten connections to connect to other nodes with ten connections than one with one or two connections. The Internet is heterogenous. So, take UUnet as your nodes at the AS level and lets say it has 1700 or so connections to other AS's. Most of those other AS's would not not also have 1700 connections, thus it is heterogenous. Lots of problems in applying that to cascading failures in reality - making AS701 disappear, BGP allowing a cascading traffic failure from "having to redistribute" AS701's traffic etc etc. Hope that makes it more clear, but it is just my interpretation of someone elses work. ----- Original Message ----- From: Douglas Denault <doug(a)safeport.com> Date: Saturday, February 8, 2003 3:23 pm Subject: Re: Cascading Failures Could Crash the Global Internet > I believe the answer meant heterogenous has a meaning in a > statistical context. > As I was a Real Variables guy I, was weak on statistics (of my > day). Math guys > love to use perfectly good English words giving them different > meanings. > Assuming that the given definition is correct, the applicability > of the > assumption to the backbone is still not clear to me. While not > doubting the > mathematical model, it seems to me there is little empirical > evidence to support > it in this context. Or I am in the second half of your second point. > > On 8 Feb 2003, Michael Lamoureux wrote: > > > "sgorman1" == sgorman1 <sgorman1(a)gmu.edu> writes: > > > > sgorman1> I believe the comments about heterogenous networks has > to do > > sgorman1> with a measurement called assortivitiy that is used in > > sgorman1> statistical mechanics. A homogenous network is when nodes > > sgorman1> connect preferentially to nodes like them. In a > > sgorman1> heterogenous network they connect to nodes that are > not like > > sgorman1> them. For networks like the Intneret and the electric > grid> sgorman1> it is measured by the number of connections a node > has.> > > sgorman1> The kicker, that the author's are alluding to, is that the > > sgorman1> more heterogenous a network is the more vulnerable it > is to > > sgorman1> targeted attack. By taking out a highly connected > node - > > sgorman1> lots of poorly connected nodes that use it as a hub are > > sgorman1> lost. The AS network had the highest heterogenous > score of > > sgorman1> real-world tested networks, so lots of folks on that > > sgorman1> bandwagon. > > > > I don't see how the fact that a network is homogeneous or > > heterogeneous has anything to do with how well connected it is. The > > only possible sense to this I can see is that, statistically, > you are > > more likely to have a platform that the attacker has a viable attack > > for if you have lots of different platforms. But at the same > time, if > > the attacker only has one exploit (or whatever attack vector), then > > you are also in a MUCH better position than someone who's > network is > > made up 100% of that platform. I'm still not sure how having a > > homogeneous network helps. > > > > Either you aren't explaining it well, or I'm being stupid. I > consider> both possibilities to be equally likely at this point. > ;-) > > > > > > IMHO, > > Michael > > > > _____ > Douglas Denault > doug(a)safeport.com > Voice: 301-469-8766 > Fax: 301-469-0601 > > >

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Re: Cascading Failures Could Crash the Global Internet
by Michael Lamoureux 08 Feb '03

08 Feb '03

"sgorman1" == sgorman1 <sgorman1(a)gmu.edu> writes: sgorman1> I believe the comments about heterogenous networks has to do sgorman1> with a measurement called assortivitiy that is used in sgorman1> statistical mechanics. A homogenous network is when nodes sgorman1> connect preferentially to nodes like them. In a sgorman1> heterogenous network they connect to nodes that are not like sgorman1> them. For networks like the Intneret and the electric grid sgorman1> it is measured by the number of connections a node has. sgorman1> The kicker, that the author's are alluding to, is that the sgorman1> more heterogenous a network is the more vulnerable it is to sgorman1> targeted attack. By taking out a highly connected node - sgorman1> lots of poorly connected nodes that use it as a hub are sgorman1> lost. The AS network had the highest heterogenous score of sgorman1> real-world tested networks, so lots of folks on that sgorman1> bandwagon. I don't see how the fact that a network is homogeneous or heterogeneous has anything to do with how well connected it is. The only possible sense to this I can see is that, statistically, you are more likely to have a platform that the attacker has a viable attack for if you have lots of different platforms. But at the same time, if the attacker only has one exploit (or whatever attack vector), then you are also in a MUCH better position than someone who's network is made up 100% of that platform. I'm still not sure how having a homogeneous network helps. Either you aren't explaining it well, or I'm being stupid. I consider both possibilities to be equally likely at this point. ;-) IMHO, Michael

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RE: Cisco 7507, erratic behaviour
by Newell, Tony 08 Feb '03

08 Feb '03

Drew, I'm sure that by now you have reloaded your router and everything is working great; however, in the future treat this issue like a memory usage problem. When this problem returns here are some things you can look for; 1. Low processing memory 2. Too many telnet sessions 3. Hung TCP connections 4. Memory fragmentation Tony Newell -----Original Message----- From: Haesu [mailto:haesu@towardex.com] Sent: Friday, February 07, 2003 4:28 PM To: Drew Weaver Cc: 'nanog(a)merit.edu' Subject: Re: Cisco 7507, erratic behaviour I've seen that before. It's usually okay to just leave it running unless you really have a need to show the running-config at this hour. If I were you, I would wait and reboot the whole thing at like 4 in the morning when not many people are online. -hc On Fri, 7 Feb 2003, Drew Weaver wrote: > Howdy, Im having a little difficulty with a 7507, when I do sh run > it just returns a newline and doesn't show me any the running-configuration. My privelege level is 15, and this worked yesterday. I also did wr term, > same thing.. New line.. Nothing.. My start-config hasn't been modified, and > show start works great. Everything is working Ok in the router, however I am > concerned for obvious reasons. ;-) ***** "The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential, proprietary, and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from all computers."

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Re: Cascading Failures Could Crash the Global Internet
by sgorman1＠gmu.edu 08 Feb '03

08 Feb '03

I believe the comments about heterogenous networks has to do with a measurement called assortivitiy that is used in statistical mechanics. A homogenous network is when nodes connect preferentially to nodes like them. In a heterogenous network they connect to nodes that are not like them. For networks like the Intneret and the electric grid it is measured by the number of connections a node has. The kicker, that the author's are alluding to, is that the more heterogenous a network is the more vulnerable it is to targeted attack. By taking out a highly connected node - lots of poorly connected nodes that use it as a hub are lost. The AS network had the highest heterogenous score of real-world tested networks, so lots of folks on that bandwagon. That said I don't think the tolerance parameter they set up in the paper makes much sense when applied to the Internet at the AS level. Basically it says once traffic exceeds a certain threshold the node will fail and cause cascades across the network. You guys are the experts but that does not sound overly realistic. ----- Original Message ----- From: Douglas Denault <doug(a)safeport.com> Date: Saturday, February 8, 2003 7:31 am Subject: Re: Cascading Failures Could Crash the Global Internet > > The model proposed makes several assumptions. My question is about: > > Many real-world networks are heterogeneous and as such are > expected to > undergo large-scale cascades if some vital nodes are attacked. > > on page 3. I do not get the basis for this assumption. So any help > for a 60's > educated math major would be appreciated. > > > On Thu, 6 Feb 2003 sgorman1(a)gmu.edu wrote: > > > > > The paper is avaibable on the Los Alamos site free of charge: > > > > http://xxx.lanl.gov/PS_cache/cond-mat/pdf/0301/0301086.pdf > > > > > > > > ----- Original Message ----- > > From: Sean Donelan <sean(a)donelan.com> > > Date: Thursday, February 6, 2003 12:43 pm > > Subject: Cascading Failures Could Crash the Global Internet > > > > > > > > > > > Sigh, there are differences between tightly coupled networks, > such as > > > the electric power grid and loosely couple networks like the > > Internet. > > > But there are also some similarities, such as electric grids > use DC > > > interconnections to limit how far AC disturbances propagate; the > > > Internet uses AS interconnections to limit IGP disturbances from > > > propagating. > > > > > > http://sci.newsfactor.com/perl/story/20686.html > > > > > > The actual article requires payment to read > > > http://ojps.aip.org/getabs/servlet/GetabsServlet? > > prog=normal&id=PLEEE8000066000006065102000001&idtype=cvips&gifs=Yes > > > > > > > > > > > > > _____ > Douglas Denault > doug(a)safeport.com > Voice: 301-469-8766 > Fax: 301-469-0601 > > >

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Re: Cascading Failures Could Crash the Global Internet
by sgorman1＠gmu.edu 08 Feb '03

08 Feb '03

The paper is avaibable on the Los Alamos site free of charge: http://xxx.lanl.gov/PS_cache/cond-mat/pdf/0301/0301086.pdf ----- Original Message ----- From: Sean Donelan <sean(a)donelan.com> Date: Thursday, February 6, 2003 12:43 pm Subject: Cascading Failures Could Crash the Global Internet > > > Sigh, there are differences between tightly coupled networks, such as > the electric power grid and loosely couple networks like the Internet. > But there are also some similarities, such as electric grids use DC > interconnections to limit how far AC disturbances propagate; the > Internet uses AS interconnections to limit IGP disturbances from > propagating. > > http://sci.newsfactor.com/perl/story/20686.html > > The actual article requires payment to read > http://ojps.aip.org/getabs/servlet/GetabsServlet? prog=normal&id=PLEEE8000066000006065102000001&idtype=cvips&gifs=Yes > > >

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Re: Odd DNS responses for www.neopets.com
by Crist J. Clark 07 Feb '03

07 Feb '03

David Russell wrote: > > Maybe it's just me, but isn't there something odd about a DNS query > > coming back with 78 entries for the same host? It sends back an UDP > > packet that gets truncated and the DNS resolver reverts to TCP to get > > the full list. [snip] > > > > It seems to cause problems with Windows clients and/or Windows DNS > > servers. Seems like overkill. > > > I feel your pain because I use a DNS module in my scripts that craps out > when it sees one of these truncated packets, but then the problem is with > the client and not DNS. It is too bad that the DNS packet size can't be > increased to 1500B. It can, RFC2671. -- Crist J. Clark | cjclark(a)alum.mit.edu | cjclark(a)jhu.edu http://people.freebsd.org/~cjc/ | cjc(a)freebsd.org

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OFF-TOPIC RE: Cisco 7507, erratic behaviour
by Lane Patterson 07 Feb '03

07 Feb '03

This subject is a bit off-topic for Nanog. You may have more success calling Cisco TAC and if you still need to, posting this kind of stuff to cisco-nsp: http://puck.nether.net/cisco-nsp/ Cheers, -Lane > -----Original Message----- > From: Drew Weaver [mailto:drew.weaver@thenap.com] > Sent: Friday, February 07, 2003 1:12 PM > To: 'nanog(a)merit.edu' > Subject: Cisco 7507, erratic behaviour > > > > Howdy, Im having a little difficulty with a 7507, when > I do sh run > it just returns a newline and doesn't show me any the > running-configuration. > My privelege level is 15, and this worked yesterday. I also > did wr term, > same thing.. New line.. Nothing.. My start-config hasn't been > modified, and > show start works great. Everything is working Ok in the > router, however I am > concerned for obvious reasons. ;-) > > Thanks, > -Drew >

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RADB news and NANOG helpdesk hours
by Larry J. Blunk 07 Feb '03

07 Feb '03

This is an update on recent changes to the Merit RADB Internet routing registry and announcement of helpdesk hours at the Phoenix NANOG meeting. In December of 2002, the RADB was officially rechristened the "Merit Routing Assets Database" and a redesigned website at www.radb.net was unveiled. In addition, there is now a web-based interface for RADB additions and updates. This interface may be reached at the following URL -- http://www.radb.net/cgi-bin/radb/irr-web.cgi. Merit has been actively involved with the RPSLng effort to update the RPSL standard to support IPv6 and Multicast routing policy. We have an initial implementation of the specification as documented in the following Internet draft: http://www.ietf.org/internet-drafts/draft-damas-rpslng-00.txt We expect to deploy this implementation in RADB registry shortly. In addition, we are working with Internet2 members to develop the I2 routing registry as an IPv6 routing registry and resource for the Internet2 community. The RADB team will once again hold a helpdesk at the NANOG meeting. Helpdesk hours are as follows: monday 10:15 break monday 3:00 break tuesday 10:35 break tuesday 12:00 lunch Regards, Larry J. Blunk Merit RADB

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Cascading Failures Could Crash the Global Internet
by Sean Donelan 07 Feb '03

07 Feb '03

Sigh, there are differences between tightly coupled networks, such as the electric power grid and loosely couple networks like the Internet. But there are also some similarities, such as electric grids use DC interconnections to limit how far AC disturbances propagate; the Internet uses AS interconnections to limit IGP disturbances from propagating. http://sci.newsfactor.com/perl/story/20686.html The actual article requires payment to read http://ojps.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PLEEE800006…

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