OfWolfAndMan February 2016
You won't be able to summarize them unless they are sequential.
For example, let's say you have a few network prefixes:
10.1.1.1 and 10.1.1.2 for a peer to peer link
10.5.4.0/24 for a user network and 10.5.5.0/24 for their VoIP phones.
10.1.1.1 and 10.1.1.2 can be aggregated as 10.1.1.0/30, 10.1.1.0 being the network address and 10.1.1.3 as the broadcast.
The second set could be summarized as 10.5.4.0/23, 10.5.5.255 being broadcast.
If they are not in sequence and not in increments of 2 (2,4,8,16,32,etc), then you will be limited.