VPN Impact on Firewall

[wajid_dabir]

Dear Team,

Recently we have configured Site-Site VPN on box ASA 5525 to access remote machines via RDP. Is it possible to know how much RAM/CPU would be utilizing for the VPN connection as I have to record for reference? Also wanted to understand how many users access we can allow over it so that it shouldn't' t impact the other services.

[Ryan Wolfe]

Hello Wajid,

I don't think there is a way to view specific CPU/RAM consumption by the VPN process itself. I would simply go by the spec sheet for connections per second to gauge what the total capabilities for the box are.

I've never seen any VPN-specific numbers as far as speeds, feeds, etc.

You could use the "show processes cpu-usage" command and find VPN specific processes to track usage of as a metric; however, I don't know any specific processes that would be the best indicator. You could start with something like the below:

ciscoasa# show processes cpu-usage | i VPN|vpn|rypt 
0x0000000000d2f5ef   0x00007fffeca4ba60     0.0%     0.0%     0.0%   WebVPN KCD Process
0x0000000001c5cc74   0x00007fffeca35380     0.0%     0.0%     0.0%   vpnlb_timer_thread
0x0000000001c5cea2   0x00007fffeca39fa0     0.0%     0.0%     0.0%   vpnlb_thread
0x0000000001c42508   0x00007fffeca1fec0     0.0%     0.0%     0.0%   vpnfol_thread_unsent
0x0000000001c423a5   0x00007fffeca20600     0.0%     0.0%     0.0%   vpnfol_thread_timer
0x0000000001c41e30   0x00007fffeca20260     0.0%     0.0%     0.0%   vpnfol_thread_sync
0x0000000001c41a3d   0x00007fffeca209a0     0.0%     0.0%     0.0%   vpnfol_thread_msg
0x000000000166da35   0x00007fffeca320c0     0.0%     0.0%     0.0%   Crypto PKI RECV
0x00000000016f0376   0x00007fffeca10840     0.0%     0.0%     0.0%   Crypto CA Server
0x00000000016f0376   0x00007fffec9dcdc0     0.0%     0.0%     0.0%   Crypto CA Server
0x00000000016f0376   0x00007fffec88ca40     0.0%     0.0%     0.0%   Crypto CA Server
0x000000000166ea4f   0x00007fffeca32800     0.0%     0.0%     0.0%   Crypto CA
0x0000000000834519   0x00007fffeca348a0     0.0%     0.0%     0.0%   CP Crypto Result Processing

HTH,

Ryan