BGP UPDATE and ROUTE REFRESH packets

[riad1990new]

Hello,

I'm trying to understand how often BGP UPDATE messages get exchanged between neighbors, I understand that when a BGP neighborship is first established, UPDATE messages get exchanged between neighbors, but let's say I've applied a routing-policy change, for example:

* I've added a new network command for prefix A.

* I've configured a filter for prefix B.

Would an UPDATE message get sent out to BGP neighbors in both cases? or just the case of the advertised prefix with the network command?

If UPDATE messages are sent when changes are configured and networks become unavailable, then why do we need features such as SOFT-RECONFIGURATION, or ROUTE-REFRESH BGP packets?

Thanks,
Riad.