Forum Discussion
A layer 4 virtual server will allow you to apply and iRule that can perform actions at layer 4 events, like matching against destination port numbers.
Both servers will forward the initial SYN to its destination without waiting for the handshake to complete on the frontend. Using these profiles the f5 is effectively routing.
- Frank_30530Mar 28, 2017Altocumulus
Thanks for the answer.
I know that you can do a lot more with Performance L4 VS, and I found out that both VS seem to be effectively routing (L3) traffic on a packet-per-packet basis.
However, are both L3 and L4 vS definitions indeed equal, or are there some 'hidden' (subtle) differences that I did not notice?...
- keshav_163381Mar 28, 2017Nimbostratus
Hi Frank, Here you can see actual difference between both the virtual types.
https://support.f5.com/csp/article/K14163
- Frank_30530Mar 29, 2017Altocumulus
Hi,
Thanks for pointing me to this article. I was looking for some more in-depth information. This article states:
Forwarding IP: A Forwarding (IP) virtual server forwards packets directly to the destination IP address specified in the client request. A Forwarding (IP) virtual server has no pool members to load balance.
and:
A Performance (Layer 4) virtual server has a FastL4 profile associated with it. A Performance (Layer 4) virtual server increases the speed at which the virtual server processes packets.
In my config example, both VS (L3 and L4) have no pool(members) attached. Also: a Forwarding IP VS also has a FastL4 profile attached (just like the L4, as the article states).
Hence, my question: what is the difference between the two definitions. Perhaps the answer is: in this case they are both identical, but then I wonder, why have two separate versions of the VS instead of just the Performance L4 type, which might behave as an IP Forwarding when you omit the pool?
- kubatrak_52714Mar 30, 2017Nimbostratus
The big difference is L3 is purely acting as a router and Performance (L4) has Load Balancer capabilities. Perfromance(L4) doesn't work in full-proxy mode (standard type), just routing traffic like a router does.
Check this link out:
https://support.f5.com/csp/article/K8082
If you don't have a pool configured on Performance (L4), then there is no so much difference between them because you can't use L4 features (http profile, load balancing, etc). I'd use Forwarding (L3) if you have to choose between both for this specific case