WARNING: Executing show cdp neighbors detail may crash your Cisco at Mae-EAST. I noticed this earlier today while I was browsing, but believed I had some sort of strange interaction with my rev of IOS until this happened to someone else running a completely different code stream. There is apparently a device there spewing broken cdp information. The Cisco engineer working on this case hasn't heard of this problem before, but if I gather anymore useful information I'll certainly pass it along. -Golan
A few of you have asked which rev. this is known to happen on, so I'm forwarding this to the rest of nanog: Cisco Internetwork Operating System Software IOS (tm) GS Software (GS7-K-M), Version 11.0(9), RELEASE SOFTWARE (fc1) Copyright (c) 1986-1996 by cisco Systems, Inc. Compiled Tue 11-Jun-96 03:52 by loreilly Image text-base: 0x00001000, data-base: 0x007614F0 ROM: System Bootstrap, Version 11.0(9), SOFTWARE cisco RP1 (68040) processor (revision A0) with 65536K bytes of memory. - This appears to happen also under the 11.2 code stream (which specific rev I'm not yet clear, as I don't currently have direct access to the information). As this becomes more clear, I'll make it available to those interested parties. Also, if you're crazy enough to test this on your equipment, let us know :) On Wed, 14 May 1997, Golan Ben-Oni wrote:
WARNING:
Executing show cdp neighbors detail may crash your Cisco at Mae-EAST. I noticed this earlier today while I was browsing, but believed I had some sort of strange interaction with my rev of IOS until this happened to someone else running a completely different code stream.
There is apparently a device there spewing broken cdp information. The Cisco engineer working on this case hasn't heard of this problem before, but if I gather anymore useful information I'll certainly pass it along.
-Golan
Golan,
Executing show cdp neighbors detail may crash your Cisco at Mae-EAST. I noticed this earlier today while I was browsing, but believed I had some sort of strange interaction with my rev of IOS until this happened to someone else running a completely different code stream.
I can confirm (to my cost a couple of weeks ago) that this reliably and repeatably shafts a 7010 running 11.0.11. I think we opened a case with TAC. I'd tend to avoid CDP entirely. Alex Bligh Xara Networks
WARNING:
Executing show cdp neighbors detail may crash your Cisco at Mae-EAST. I noticed this earlier today while I was browsing, but believed I had some sort of strange interaction with my rev of IOS until this happened to someone else running a completely different code stream.
There is apparently a device there spewing broken cdp information. The Cisco engineer working on this case hasn't heard of this problem before, but if I gather anymore useful information I'll certainly pass it along.
-Golan
Why on EARTH?!? would _ANYONE_ run CDP at a MAE or any other exchange point? Especially given the congestion, and other problems at the MAE's, why run a protocol to discover other Cisco's you have to explicitly configure peering sessions with anyway? If someone can explain a reason not to turn off CDP at an exchange point, I'm all ears. Owen
Why on EARTH?!? would _ANYONE_ run CDP at a MAE or any other exchange point? because it's on by default?
-peter
int fddi ??/?? no cdp-enable
Owen
But how will you know whom has placed L2 switches at an exchange unless you run cdp? Oh yeah... exchanges are for not just for routers anymore.. :) -- --bill
Owen DeLong wrote:
Why on EARTH?!? would _ANYONE_ run CDP at a MAE or any other exchange point?
because it's on by default?
Oh, then why run BGP? It's off by default.
:) very good. I wasn't being deliberately stupid, just pointing out that one might not know that it's on by default. Why do I need a way to autodiscover my routers? I know where they all are-- I put them in after all. What I'm saying is that CDP is a "negative checkoff" item-- like those little boxes when you download software that say, "check here if you DO NOT wish to receive email when we produce yet another upgrade." If you don't check the box, you will get mail. If you don't turn CDP off, CDP is on. This is nonobvious to those new to the business. -peter
Well, it makes you wonder why Cisco changed it so that IP routing is now turned off by default. It used to be on by default, or at least when up put an ip address on an interface. What really kills me, is that if you buy a small router, say a 2501 that is only licensed for IP, it comes with CDP on, and IP off by default. Eric _______________________________________________________ Eric D. Madison - Senior Network Engineer - ACSI - Advanced Data Services - ATM/IP Backbone Group 24 Hour NMC/NOC (800)291-7889 Email: noc@acsi.net On Wed, 14 May 1997, Peter wrote:
Owen DeLong wrote:
Why on EARTH?!? would _ANYONE_ run CDP at a MAE or any other exchange point?
because it's on by default?
Oh, then why run BGP? It's off by default.
:) very good. I wasn't being deliberately stupid, just pointing out that one might not know that it's on by default. Why do I need a way to autodiscover my routers? I know where they all are-- I put them in after all.
What I'm saying is that CDP is a "negative checkoff" item-- like those little boxes when you download software that say, "check here if you DO NOT wish to receive email when we produce yet another upgrade." If you don't check the box, you will get mail.
If you don't turn CDP off, CDP is on. This is nonobvious to those new to the business.
-peter
Why on EARTH?!? would _ANYONE_ run CDP at a MAE or any other exchange point?
You would be suprised at the large number of folks who've got CDP enabled at the exchange points -- Ironically, we enabled it to get a sense of what other IOS versions were running on our peers routers prior to a code upgrade to fix some issues that were affecting us.
Especially given the congestion, and other problems at the MAE's, why run a protocol to discover other Cisco's you have to explicitly configure peering sessions with anyway? If someone can explain a reason not to turn off CDP at an exchange point, I'm all ears.
Given that its on by default cdp needs to either be turned off completely, or disabled for a particular interface, folks probably just leave it on. I highly doubt CDP contributes to congestion problems with the little amount of traffic it generates - Although if you've ever looked at some of the traffic at the Mae's you'd be sickened by all of the other things floating around. I suppose another eason to disable CDP in addition to disabling any non-essencial traffic and/or processes would be for privacy.
Among many other things, CDP has been used very effectively in the past to see if routing anomalies are correlated with router/software versions. randy
participants (7)
-
Alex.Bligh -
bmanning＠ISI.EDU -
Eric D. Madison -
Golan Ben-Oni -
owen＠DeLong.SJ.CA.US -
Peter -
randy＠psg.com