In reply to Karl Hanson.

Hi Karl,

If you have an ESP10 you will be able to hold 1,000,000 IPv4 routes. As mentioned earlier, the ESP 10 supports:
1,000,000 IPv4 or 500,000 IPv6 routes
Multicast: 64,000 routes and 1,000 groups

The following is the Cisco ASR 1000 Series Embedded Services Processors (ESP) Data Sheet, which lists the limits of each ESP model:

http://www.cisco.com/c/en/us/products/collateral/routers/asr-1000-series-aggregation-services-routers/datasheet-c78-731640.html?cachemode=refresh

Hope this helps!

Omar