It really depends here on what resource you're running out of here. You say you're running out of ram, which means you should see a MALLOCFAIL message when you're downloading the BGP tables. Is this what you're getting?

If so, the fix is as simple as adding RAM to either the SUP or MSFC as needed. Since the order of operations to program our hardware tables is:

1. Download & Process BGP routes

2. Put best routes in routing table

3. Program software CEF tables

4. Program software CEF tables on SUP side

5. Program hardware from SUP's CEF tables

Make sure you pay attention to whether you ran out of memory on the SUP or the MSFC. Whichever one ran out, you'll want to upgrade.

Now if you ran out of memory in hardware, sometimes you'll see a TCAM full message, sometimes packets will take the wrong route, and sometimes you'll see high cpu. If this is the case, there are things you can do on the SUP720-3B to re-allocate your TCAM to allow more routes. What you want to do is:

config t

mls cef maximum-routes ip 220

By default we carve the TCAM to only allow 192k IPv4 unicast routes. The number you specify here allows you to raise that amount (at the expense of IPv4 multicast routes). The max you can do is 239K.

If you have more than 239K routes to put into hardware, or if you're doing a lot of multicast, you'll want to replace these guys with SUP720-3BXL.