[c-nsp] WAAS and minimum latency

[James Michael Keller]

Tim,

I doubt you will see improvement over 3ms for general latency reduction 
(assuming a OCX P-t-P link?).  However it will improve CIFS performance 
if the files are being accessed and changed a lot by the users at the 
site remote from the CIFS server.   The WAE on the server side of the 
link will cache operations locally.   So say you move a file between 
CIFS shares, normally that comes back through the client and back down 
to another share.    With the WAE unit it will proxy that operation and 
the operation completes at local LAN speed instead of WAN speed through 
the remote client and back to the other server.   While WAE's will 
fiddle with TCP settings to improve some performance, the main function 
in the current release code is the data reduction features.  Either the 
raw DRE caches or application level proxies (CIFS/MAPI,NFS, etc).   
Latency may not improve, but effective speed and bandwidth will go up.

For our MPLS connected sites in the 50ms+ range, there is some 
improvement of the RTT of around 40% on average across all the sites.    
Traffic reduction runs an average of 30% with Content and version 
management protocols and CIFS/MAPI making up the bulk of the traffic 
reduction (all above 50%) .  The main non-optimized traffic is internet 
bound in our case, as we centrally route internet out a data center from 
the MPLS connected sites.

---
James Michael Keller



Tim Durack wrote:
> Anyone got figures on the *minimum* latency the various WAN accelerators can
> improve on?
>
> I ask as I have a customer with a couple of sites connected via GigE. RTT
> for SiteA -> SiteB is around 3ms. Migrating services between sites has
> reduced performance for some users (appears that SMB/CIFS is most affected.)
>
> I'm looking to see if I can "fix" things with WAAS, just not sure they are
> really designed for this scenario (I'm not a fan of WAAS, but if it fixes a
> problem...)
>
> Thanks,
>
> Tim:>
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