No more memory than default is needed.

Beside, 3750 memory is not expandable.

Hello Jan,

main memory is not a problem as noted by Paolo.

You can exstimate 1 KByte memory for each prefix (including BGP and CEF).

Being a multilayer switch it is very important that all prefixes can be hosted in the TCAM table (this means efficient L3 forwarding).

TCAM usage depends on deployed strategy called SDM template

Be aware of the following:

see table 8-1

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_46_se/configuration/guide/swsdm.html

With a routing SDM template TCAM can handle 6,000 MAC address and 20K ipv4 routes.

change of SDM template is effective only after reload.

And you need an IP services image to run BGP

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_46_se/configuration/guide/swiprout.html#wp1226539

You should be fine.

Hope to help

Giuseppe