Well I would say your answer is more accurate but the answer in the book is still OK.
As Cisco will hold the route in the table until it confirms the other route is stable and more preferred what you are seeing is the expected behavior. You are not getting another route to replace it or it would remove it on the second update and only hold the old one in the RIP database until it expires. Regards, Tyson Scott - CCIE #13513 R&S, Security, and SP Managing Partner / Sr. Instructor - IPexpert, Inc. Mailto: <mailto:[email protected]> [email protected] Telephone: +1.810.326.1444, ext. 208 Live Assistance, Please visit: <http://www.ipexpert.com/chat> www.ipexpert.com/chat eFax: +1.810.454.0130 IPexpert is a premier provider of Self-Study Workbooks, Video on Demand, Audio Tools, Online Hardware Rental and Classroom Training for the Cisco CCIE (R&S, Voice, Security & Service Provider) certification(s) with training locations throughout the United States, Europe, South Asia and Australia. Be sure to visit our online communities at <http://www.ipexpert.com/communities> www.ipexpert.com/communities and our public website at <http://www.ipexpert.com/> www.ipexpert.com From: [email protected] [mailto:[email protected]] On Behalf Of Bojan Zivancevic Sent: Monday, September 20, 2010 12:34 PM To: 'CCIE_RS OnlineStudyList' Subject: [OSL | CCIE_RS] vol.1 task 8.13 problem (route poisoning) First, I think there is an error in DSG. Second, I stumbled into an interesting behavior of the "distance" command. This is a task about RIP route poisoning. We can go for offset-list method or distance one. The WB goes for distance, ok. DSG says that we should enter "distance 255 150.100.12.2 255.255.255.255 1" which IMHO is wrong. The context help and command reference agree that we should enter wilcard there, and not the subnet mask. So, it should be "150.100.12.2 0.0.0.0". That can be confirmed with "sh run | i distance" which then show that the router automatically converted the distance command into "distance 255 0.0.0.0 255.255.255.255 1" because of the "ANY" wildcard used. So, I think it is definite that we should use wildcard. Anyway, I tried it this way and it worked. But... Now, about the second part of my email. I would really love somebody to explain why is this happening. When I corrected the "distance" command, I noticed that the update timer has not been reset anymore. The route just slowly started to dissapear. That confused me and I thought all this is not working. That is why I changed the distance to "254" in order to be able to see the route in the table even after the command. All other routes behaved normal, just this one. So, i chose to wait and saw that the distance command did have the effect, but only after the flush timer has expired, the route got deleted from the table, and another RIP update came after that. Only then the AD got changed to 254... Why the router is not changing the distance immediately after the next RIP update? Why the flush timer and all? See for yourself: R1(config-router)#do sho access-l 1 Standard IP access list 1 10 permit 200.0.0.9 (75 matches) R1(config-router)#do sh run | i dista distance 254 150.100.12.2 0.0.0.0 1 .... and we still have the old "120" distance... R1(config-router)#do sro 200.0.0.9 Routing entry for 200.0.0.9/32 Known via "rip", distance 120, metric 3 Redistributing via rip Last update from 150.100.12.2 on FastEthernet0/0, 00:00:28 ago ..... time is passing... R1(config-router)#do sro 200.0.0.9 Routing entry for 200.0.0.9/32 Known via "rip", distance 120, metric 3 Redistributing via rip Last update from 150.100.12.2 on FastEthernet0/0, 00:02:54 ago ... some more... R1(config-router)#do sro 200.0.0.9 Routing entry for 200.0.0.9/32 Known via "rip", distance 120, metric 4294967295 (inaccessible) Redistributing via rip Last update from 150.100.12.2 on FastEthernet0/0, 00:04:01 ago .... and here it is, the new AD... R1(config-router)#do sro 200.0.0.9 Routing entry for 200.0.0.9/32 Known via "rip", distance 254, metric 3 Redistributing via rip Last update from 150.100.12.2 on FastEthernet0/0, 00:00:20 ago Best Regards, Bojan Zivancevic Network Engineer
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