1, 1 Successor(s), FD is 128256 Routing Descriptor Blocks: 0.0.0.0, from Rconnected, Send flag is 0x0 Composite metric is (128256/0), Route is External Vector metric: Minimum bandwidth is 10000000 Kbit Total delay is 5000 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1514 Hop count is 0 External data: Originating router is 50.50.50.1 (this system) AS number of route is 0 External protocol is Connected, external metric is 0 Administrator tag is 3 (0x00000003) The last line shows the administrator tag as 3, indicating that routes redistributed into EIGRP (specifically, redistributed connected routes) have been marked with a tag of 3. EIGRP doesn't do anything with this information other than store it. So what does tagging do for you? Just as you can set a tag to apply when redistributing routes into a routing protocol, you can also test for a tag, and permit or deny redistributions based on it. Call me a nerd, but I think that's pretty cool. To check for an incoming route tag, you again must use a route map. You must do this for all routing protocols, including OSPF. Looking back at the example from Figure 11-6, consider that we've now set a tag of 3 for the connected route 50.50.50.0/24 on R3. If we could prevent this route from being advertised into OSPF, that would solve the problem, because R1 would never learn of the route improperly. On R2, when we redistribute into OSPF, we need to tell the router to call a route map. We're no longer setting the tag with the redistribute command, as we'll set it in the route map. If I'm checking for a tag using a route map, I always set it there, too. It's easier for me to understand things when I do everything in one place. I've also seen problems where setting a tag with the tag keyword and then checking for it with route maps doesn't work very well. Here, I'm telling the router to redistribute EIGRP 100 Limiting Redistribution routes into OSPF 100, assign them a metric of 10, and apply whatever logic is included in the route map No-EIGRP-Tag3: router os