IP Traffic Export is a lot like SPAN for switches, except it is for routers. A copy of traffic received on configured interfaces is exported out another interface while the original flow is not impacted.
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This is usually one of the more confusing routing protocol commands supported by Cisco. Every couple of months, there is a post about it on GroupStudy or I get a question about it. Hopefully these two scenarios answer most of your questions and show you just exactly how it works!

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When OSPF sites have a backdoor connection, they will by default prefer that link over the MPLS VPN link. Because of the redistribution that occurs, the VPN routes will be seen as inter-area (if OSPF process numbers match on PEs), E1 or E2 routes. As you probably know by now, inter-area and external routes are less preferred than intra-area routes in OSPF. No amount of administrative distance-altering or interface cost- changing can affect this decision making. Here we look briefly at a feature designed to allow VPN routes to look like intra-area routes, giving us the ability to prefer them over the VPN connection by adjusting interface costs.

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In this post we look at a sometimes misunderstood command, ip pim rp-announce-filter, and figure out how it is used to filter unwanted devices from becoming RPs. The topology for this example is very small, just two routers.

R1—R2

Requirements:

R1 = 1.1.1.1, R2 = 2.2.2.2

R1 is the Mapping Agent.

R1 should be the RP for 239.0.0.1.

No other router device should be allowed to be RP for any other group.
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Often when you are a few hours into a lab, some things become a little hazy. You are flying by and everything is working as expected, then you run into a snag. You know the answer will be easy, once you find it. Forgetting to configure route reflection can be one of those things. In this post, we look at the show ip bgp neighbor command to figure how the router tells us that there is no reflection going on. This is of course assuming you couldn’t figure it out with a show run (which happens a lot!).

 
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