I did not fully examine your route-map but I know Marko has mentioned in his lectures (I believe in the audio course but I may be wrong.) that tagging everything is a sure bet to prevent routing loops without the need to second guess whether the routing protocol handles it inherently.
Some routing protocols inherently prevent routing loops such as OSPF and EIGRP, to ensure that there is no possibility of a loop, route-maps can be used. Tyson and Marko reviewed the maps and believed they looked good and "debug ip routing" indicated that no loops exist Thoughts? From: Jay Taylor [mailto:[email protected]] Sent: September-24-10 8:20 PM To: Jason Maynard Cc: [email protected] Subject: Re: [OSL | CCIE_RS] VOL3-LAB5 - Ticket6 I'm working on this ticket right now and looking at your route-maps it may work but you have 1 extra statements in each for dealing with redistribution between 3 routing protocols. The way I built mine for this ticket were identical to Marko's in the video solution to the lab. The way I think of it is: 1st statement - deny tags with the AD of the destination routing protocol 2nd statement - match and tag the protocol that isn't involved in that particular route-map with its own AD 3rd statement - tag the source routing protocol with its own AD route-map OSPF-2-RIP deny 10 match tag 120 ! route-map OSPF-2-RIP permit 20 match tag 90 set tag 90 ! route-map OSPF-2-RIP permit 30 set tag 110 ! ! ! route-map OSPF-2-EIGRP deny 10 match tag 90 ! route-map OSPF-2-EIGRP permit 20 match tag 120 set tag 120 ! route-map OSPF-2-EIGRP permit 30 set tag 110 ! ! ! route-map RIP-2-EIGRP deny 10 match tag 90 ! route-map RIP-2-EIGRP permit 20 match tag 110 set tag 110 ! route-map RIP-2-EIGRP permit 30 set tag 120 ! ! ! route-map RIP-2-OSPF deny 10 match tag 110 ! route-map RIP-2-OSPF permit 20 match tag 90 set tag 90 ! route-map RIP-2-OSPF permit 30 set tag 120 ! ! ! route-map EIGRP-2-RIP deny 10 match tag 120 ! route-map EIGRP-2-RIP permit 20 match tag 110 set tag 110 ! route-map EIGRP-2-RIP permit 30 set tag 90 ! ! ! route-map EIGRP-2-OSPF deny 10 match tag 110 ! route-map EIGRP-2-OSPF permit 20 match tag 120 set tag 120 ! route-map EIGRP-2-OSPF permit 30 set tag 90 On Wed, Sep 22, 2010 at 9:26 PM, Jason Maynard <[email protected]> wrote: Hey guys can you confirm whether my route-map works and ensures not loops could form. The DSG has allot less configuration but I know Marko has mentioned in his lectures that tags just ensure that loops cannot for even if routing protocols have mechanisms to prevent them. (Marko, I hope I have this right and if not I am sure you will correct me :P ) Redistribution and ensure that there is no LOOPs R4 __ Protocols EIGRP and OSPF route-map O-E deny 10 match tag 90 ! route-map O-E permit 20 match tag 110 set tag 110 ! route-map O-E permit 25 match tag 120 set tag 120 ! route-map O-E permit 30 set tag 90 ! route-map E-O deny 10 match tag 110 ! route-map E-O permit 20 match tag 90 set tag 90 ! route-map E-O permit 25 match tag 120 set tag 120 ! route-map E-O permit 30 set tag 110 R7 __ Protocols EIGRP and OSPF and RIP route-map O-E deny 10 match tag 90 ! route-map O-E permit 20 match tag 110 set tag 110 ! route-map O-E permit 25 match tag 120 set tag 120 ! route-map O-E permit 30 set tag 90 ! route-map E-O deny 10 match tag 110 ! route-map E-O permit 20 match tag 90 set tag 90 ! route-map E-O permit 25 match tag 120 set tag 120 ! route-map E-O permit 30 set tag 110 ! route-map R-O deny 10 match tag 110 ! route-map R-O permit 20 match tag 120 set tag 120 ! route-map R-O permit 25 match tag 90 set tag 90 ! route-map R-O permit 30 set tag 120 ! route-map O-R deny 10 match tag 120 ! route-map O-R permit 20 match tag 110 set tag 110 ! route-map O-R permit 25 match tag 90 set tag 90 ! route-map O-R permit 30 set tag 120 ! route-map E-R deny 10 match tag 120 ! route-map E-R permit 20 match tag 90 set tag 90 ! route-map E-R permit 25 match tag 110 set tag 110 ! route-map E-R permit 30 set tag 120 ! route-map R-E deny 10 match tag 90 ! route-map R-E permit 20 match tag 120 set tag 120 ! route-map R-E permit 25 match tag 110 set tag 110 ! route-map R-E permit 30 set tag 90 R9 __ Protocols EIGRP and RIP route-map E-R deny 10 match tag 120 ! route-map E-R permit 20 match tag 90 set tag 90 ! route-map E-R permit 25 match tag 110 set tag 110 ! route-map E-R permit 30 set tag 120 ! route-map R-E deny 10 match tag 90 ! route-map R-E permit 20 match tag 120 set tag 120 ! route-map R-E permit 25 match tag 110 set tag 110 ! route-map R-E permit 30 set tag 90 _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
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