Re: Withdrawls and announcements attempt 2
The 30 second figure sounds pretty much like the good ol' line flap with default cisco keepalive. I was bothering cisco folks about making static routes persistent by default for quite a while. Although there's a workaround very few people actually bother to use it thus causing bouncing tail links to produce route flap. My suspiction is that this kind of flap accounts for no less than 90% of the total. Another probable contributor is RIP (shouldn't we declare it RIP already?) Most network administrators never heard of a simple maxim -- "Never use dynamic routing when you have a single path". As a result most LANs are plagued by RIP with no reason whatsoever (and many of them inject their IGP routes into BGP!) The lack of any meaningful clock source negotiation and idiotic defaults in CSU/DSUs is a major source of rapid link flap, too. It seems that most (if not all) equipment vendors simply don't have any clue of what effect their design choices have in the real world. --vadim
from Vadim:
The lack of any meaningful clock source negotiation and idiotic defaults in CSU/DSUs is a major source of rapid link flap, too. It seems that most (if not all) equipment vendors simply don't have any clue of what effect their design choices have in the real world.
BTW: Is there a mailing list for ISP related telco hardware? Or telco hardware as related to ISP's? :) We talk incessantly about BGP configs, route flaps, saturation stats and Powerpoint graphs, and I don't hear boo about CSU/DSU caveats, typical misconfigs, tips on how to spot DXC/OCU mis-options (Can You Say B8ZS through a C/O that's optioned for AMI???), NIU settings, T-Carrier analyzer tips, etc, etc, etc... I did hardware/telco at BARRNet for so long, I still have withdrawl symptoms when I see a DSX patch panel or walk into a Wiltel co-lo. Yes, I know, there are endless mailing lists about telco hardware in general, but those tend to be geared for voice apps, and besides, how long would you read it when the discussions turn to how good the latest NorTel M-1/3 is compared to Brand-X (especially when probably <-1% of ISP's would configure an M-1/3 anyway). Yeah, so you're large enough to hire a contractor to do all your telco. What about us small-fry who can't afford contractors. Case-in-point: How many of you tried to figure out why the arrow keys only worked 50% of the time when you used a telnet session to configure a Digital Link Encore DSU / Ensemble shelf? And do you know what Digital Link did as a work around (ans: use the "U" and "D" keys for up/down). Ever hook up an Encore/Ensemble to a cisco aux port? Didn't work? What did you need to wire together to make it work? Anyway, I made my point. Just curious. rob.
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avg＠postman.ncube.com -
rmg＠ranma.com