Is additional latency of 100% normal for an F5 Load Balancer??

Hi all,

 

 

We have just setup a production account with cloud infrastucture provider GoGrid (who provide free F5 LB as part of their package). What we notice is a linear, proportional delay in all our web round-trips when using the LB with an average delay of over 100% - which seems ridiculous to me but GoGrid are adamant that everything is correctly configured their side and that LB will "...of course add some latency to your requests...".

 

 

We have 1 F5 LB sitting in front of 2 web-servers (i.e. the simplest deployment possible).

 

 

Here's what I observe though Firebug or Chrome Dev Tools:

 

- Roundtrip to a particular page direct to the web-server: avg. 315ms

 

- Roundtrip to the same page through the LB: avg: 810s

 

 

Same test to a smaller page results in avg 350ms (without LB) and avg 680ms (with LB)

 

 

Note:

 

- No caching issues (all static content is cached) and payloads are identitical in both tests.

 

- We are using SSL - I asked GoGrid if perhaps the LB was also doing an SSL decryption/encryption and/or HTTP compression run (essentially duplicating what has already been done on the web-server) - They assured me this was not the case.

 

- These are steady-state results (i.e. not being skewed by first-time warm-ups / caching etc.)

 

 

Anyone have any ideas here as to what is going on (or how I can prove to GoGrid that something is wrong) - I sent them my screenshots of my timings but they can't explain it. I'm just trying to find out if this is normal. I would have thought that what is essentially a low-level, dedicated hardware switch would at most add a few milliseconds onto the round-trip time - not hundreds of milliseconds (with a load of 1 user!!).

 

 

Can anyone validate this? Any help would be much appreciated.

 

 

Thanks

 

Evan