The next attribute is the aggregator attribute. And as we already mentioned when we talked about how to generate an aggregate in BGP, the aggregator attribute is set really to indicate the IP address of the router or the BGP speaker which generates the aggregate route. This attribute is optional but when it is set, it's transitive. As I was saying before, not so many operators these days will actually use the aggregator attribute, as they will generate aggregates in many parts of their network using some of the alternative methods that I mentioned. It has been and is useful for debugging purposes, and that's really it's only use, for doing debugging. It doesn't influence the best path selection and it's generally otherwise not used by BGP itself. So when we generate the aggregate using the `aggregate-address` command in Cisco IOS, this will set the aggregator attribute to the IP address of the router generating the aggregate.

Related Documents

Exercises

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