HREAP round-trip time

[jino_jacob]

Hi All,

I would like to know if the recommended WAN latency of 100ms for Voice + Data as per the H-REAP design & deployment guide holds good if we are using locally switched WLANs + central 802.1X authentication? I read somewhere that the 100ms requirement was for WLC codes upto 5.2 and it is 300ms for the later versions, is that true?

We have a remote site with an average round-trip time of about 150ms to the WLC + round trip time of 150ms to the ACS server from the WLC. Has any one deployed H-REAP in a similar situation with Voice+Data clients and experienced any issues?

Thank you

Jino

[Stephen Rodriguez]

The 100ms/300ms is for the HREAP/Flexconnect keepalive, not for the user traffic.

If you are doing voice, you still need <150ms of round trip latency to keep from having jitter/delay on the call itself.

HTH,
Steve

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[jino_jacob]

Steve,

Thank you for responding.

If the Voice WLAN is locally switched then do we still need the 100ms roundtrip between the AP and WLC if it is only  keepalives?

[Stephen Rodriguez · Accepted solution]

You don't need to worry about the round trip between the AP and WLC.  Just make sure the phone to phone is good

HTH,
Steve

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[jino_jacob]

Stephen Rodriguez wrote:
You don't need to worry about the round trip between the AP and WLC.  Just make sure the phone to phone is good
HTH, 
Steve 
 
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Thanks Steve,

That makes Sense, as post authentication the phone to phone would be ofcourse less than 150ms when the traffic is locally switched.

But I dont understand why the recommendation in the D&D guide "Roundtrip latency must not exceed 300 milliseconds  (ms) for data and 100 ms for voice and data between the access point  and the controller"

I think it is applicable if the traffic is centrally switched?? or is there more to it, for roaming perhaps?

Thanks
Jino

[Stephen Rodriguez · Accepted solution]

correct, if centrally switched you would want 100ms, so that there is that extra 50ms for the WLC <-> AP path that gets added. 

HTH,
Steve

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[Scott Fella]

Like Steve mentioned 100/300 is recommended no matter if its local or centrally switched since this is for the keep alive. So it's best to make sure you meet the requirement in order to have a stable environment.

Sent from Cisco Technical Support iPhone App

[Scott Fella]

Well it's not recommended to use FlexConnect and 792x if possible. See this link

https://supportforums.cisco.com/docs/DOC-26863

Sent from Cisco Technical Support iPhone App

[jino_jacob]

Thanks Scott,

The Document was very helpful.