We are following a few simple tasks here, but let’s think about what is actually being asked by the various phrases in a task:
Advertise x or y into routing protocol z: What this means is that we want to use a network statement or interface configuration command to put the subnet into the routing protocol as an internal type (O – OSPF) or (D for EIGRP)
Put R1 Loopback 0 into the routing protocol and make sure it is seen as external: This means redistribute, as if you think about it, anything redistributed from one thing to another is seen as External; even if that is done locally. The redistribute process is just a mechanism of replicating something to somewhere else.
summarize: This is a funny one, as this can mean several things depending on the protocol of choice. What you basically need to know is: how each protocol supports summarization and how to manipulate it.
- OSPF for example can use either the Area x range … or the summary-address command set under the routing process. The Area Range command is used by an ABR and the summary-address is used by an ASBR; different jobs for different commands with similar results.
- BGP summarization can only be done if a subset of the summary exists within the local RIB, not the BGP RIB, but the actual RIB.
- EIGRP and RIP summarize at the interface level
- …oh and don’t forget the static route that is created by the summary, this can cause all sorts of fun and games, even though it is initially inserted as a loop prevention mechanism: Take a look at this article http://www.astorinonetworks.com/2011/07/20/summary-routes-to-null0-the-protocols-that-love-them/
Ensure that: means don’t leave it to chance; configure it properly so that it always happens no matter what!
Redistribute from: I read this as a one way redistribution from x to y protocol.
Redistribute between: I read this as a two way (mutual) redistribution between x and y protocols.
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