SNAT Confusion

[Joseph Mack NA3T]

On Sat, 17 Mar 2007, Rodre Ghorashi-Zadeh wrote:

> Hello,
>
>> 
>> So if the realserver is dead, it can't ask the 2nd request?
>> 
>
> I think the fear is more along the lines of what if the service is dead, and 
> perhaps being able to perform rolling maintenance. Also the app that I am 
> trying to get load balanced, Oracle OCS, actually mentions the f5 load 
> balancers SNAT mode, so I believe it is a pretty deep rooted requirement.

yes a few people are starting to ask about the F5 SNAT mode. 
We don't have it unfortunately.

>
>> 
>> LVS could be pure netfilter, but it would be really slow.
>> 
> Enough said. I knew there had to be a reason, now I understand why. Out of 
> curiosity do you think that this still holds true with todays hardware, gig 
> nics, dual/quad core CPUs, etc?

I expect so. I can't measure the increase in latency caused 
by LVS over just straight routing. I haven't done any 
measurements with netfilter, but everyone seems to know when 
it's on. The clock rate for everything increases at about 
the same speed - the same technology is being used for all 
new hardware - so while the absolute speed is increasing, 
the ratio of speeds remains the same. The step that was the 
bottleneck 10yrs ago is still the bottleneck today.

>
> In regards to my problem I still can't get the reply packets, once SNAT-ed, 
> sent to the realserver, and sent back to the director to be accepted by the 
> director and sent back to the client. I am thinking it might have some thing 
> to do with some of the the /proc/sys/net/ipv4 params, anyone have any ideas?

no sorry. I assume you've read the sections in the HOWTO on 
clients on realservers?

Joe
-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
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