[OT] Latency Question

Unanswered Question
Apr 12th, 2010

Hi

I'm hoping someone can point me to articles or docs/tutorials. Basically I've been doing netwokring for about four years now, although not with anything cutting edge just normal things like nat, eigrp, ospf, bgp in standard ways, I'm looking to move now but some of the roles are asking for things I don't have experience with, a often mentioned poitn is the following:

Experience of latency optimisation and the  latest advances within these technologies

I'd like some help with how I can read, learn about this. And what is possible with regards to network low latency.

Any help would be appreciated.

Regards,

Dan

I have this problem too.
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Giuseppe Larosa Mon, 04/12/2010 - 04:51

Hello Dan,

>> Experience of  latency optimisation and the  latest advances within these technologies

This means WAN optimizers like WAAS and so on. They can be seen as special proxy that attempts to optimize TCP goodput over high latency links.

To do so they attempt to minimize the number of TCP sessions and TCP session setups phases and also can use form of compression

Also the use of TCP extended window to optimize goodput.

see

http://www.cisco.com/en/US/products/ps5680/Products_Sub_Category_Home.html

low latency is never a problem of course

Hope to help

Giuseppe

dan_track Mon, 04/12/2010 - 06:00

Many thanks for that.

Would it also be correct that they may be referring to the following:

1. products that will help with low latency e.g. switches, modules

2. optimisation settings on switch modules ports i.e. try to get true 1G performance from switch ports

For the above where woudl I find information on it.

I also have question do the following impact performance, if so how?

1. Serialisation - I assume this is realted to serial circuits only, am I right?

2. signalling choices?

Any help would be apprecaited.

Thanks

Dan

sean_evershed Mon, 04/12/2010 - 05:16

Dan,

I think the question, "Experience of latency optimisation and the latest advances within these technologies" is testing what skills you may have in making the best use of expensive and limited WAN bandwidth.

A colleague of mine argues that if you have robust end to end QoS policies in place in your network then there is no need for expensive WAN optimisation appliances. In order to optimise traffic you need an appliance on both ends of the link. This adds up in costs if you have over 100 branches. All these appliances also need to be managed and maintained further adding to costs.

However this arguement ignores amongst other things the caching capabilites that some of these appliances provide.

Note that these appliances are not designed to optimise UDP traffic.

Sean

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