I am looking for advice on technique or products that can solve the
following challenge ...
Two private line T1's between A and B - one terrestial T1 with >200 ms RTT,
the other T1 is over satellite with ~500 ms RTT. The circuits are being used
for mixed VoIP (70%) and data (30%) applications. To achieve optimal voice
quality, we want to route all VoIP calls over the terrestial T1 until it is
"full", then divert all subsequent VoIP calls over the satellite T1 (**
while existing VoIP calls continue to be routed over the terrestial T1).
So it looks like I need per-flow (based on protocol, src IP, dst IP, src
port, dst port) routing. It looks like MPLS Traffic Engineering can do the
job. Is there anything else that can it with less complexity?
Ideas or recommendations?
Regards,
Joe
You may want to look at using H.323 gatekeepers with CAC (Call Admission
Control).
Here is a link to a Whitepaper on this Subject.
http://www.cisco.com/en/US/partner/tech/tk652/tk701/technologies_white_paper09186a00800da467.shtml
Patrick
VoIP over satellite? I am very sceptical about it. Better, forget such idea.
You may want to look at using H.323 gatekeepers with CAC (Call Admission
Control).
Here is a link to a Whitepaper on this Subject.
http://www.cisco.com/en/US/partner/tech/tk652/tk701/technologies_white_paper09186a00800da467.shtml
Patrick
From: "Mailing List Subscriptions" <jcc-list@thenetexpert.net>
To: <nanog@merit.edu>
Sent: Friday, March 26, 2004 7:54 PM
Subject: Overflow circuit
>
>
> I am looking for advice on technique or products that can solve the
> following challenge ...
>
> Two private line T1's between A and B - one terrestial T1 with >200 ms
RTT,
> the other T1 is over satellite with ~500 ms RTT. The circuits are being
used
> for mixed VoIP (70%) and data (30%) applications. To achieve optimal
voice
> quality, we want to route all VoIP calls over the terrestial T1 until it
is
> "full", then divert all subsequent VoIP calls over the satellite T1 (**
> while existing VoIP calls continue to be routed over the terrestial T1).
>
> So it looks like I need per-flow (based on protocol, src IP, dst IP, src
> port, dst port) routing. It looks like MPLS Traffic Engineering can do
the
I have been doing VoIP over sat to northern Canada and Latin America for
more than five years now, using Cisco routers with analog and digital voice
ports, and also IP phones. Other than the inevitable lag due to 500+ ms RTT,
the voice quality with the G.729 codec has been good. I have lost count of
the number of mining operations in northern Canada that rely in VoIP over
sat for communication with the civilized world. Some of the bigger
operations have in excess of 500+ Cisco IP phones.
Thanks for the suggestion, Patrick. But I failed to mention that in this
case, the CallManager and VoIP gateways are at site A and all the IP phones
are at site B. As far as I know, the Cisco IP phones do not use H.323
gatekeeper directly.
In order for the H.323 gatekeeper idea to work, I would need a CallManager
at site B and run an H.323 inter-cluster trunk between the CallManagers at
site A and B. Right?
Heh. Probably one of the main reasons VoIP has proliferated like it has is
because it works, and works well, over Sat.
It works, I am doing MPLS VPN's using 3662's and running VoIP toll bypass.
Customer is very pleased with the network.
Patrick
Thus spake "Mailing List Subscriptions" <jcc-list@thenetexpert.net>
Please use your real name when posting to nanog (per the AUP).
Two private line T1's between A and B - one terrestial T1 with >200
ms RTT, the other T1 is over satellite with ~500 ms RTT. The circuits
are being used for mixed VoIP (70%) and data (30%) applications. To
achieve optimal voice quality, we want to route all VoIP calls over the
terrestial T1 until it is "full", then divert all subsequent VoIP calls
over
the satellite T1 (**while existing VoIP calls continue to be routed over
the terrestial T1).
With G.729a and cRTP, you can cram over a hundred calls into a single T1;
what is the average and peak usage predicted for your deployment?
While I know it's not ideal, you may want to consider using CallMangler's
bandwidth control features to ensure voice traffic never exceeds the T1's
capacity. That way you can route all voice to the T1, all data to the
satellite, and not worry about fancy load-sharing tricks.
S
Stephen Sprunk "Stupid people surround themselves with smart
CCIE #3723 people. Smart people surround themselves with
K5SSS smart people who disagree with them." --Aaron Sorkin
VoIP over satellite? I am very sceptical about it. Better, forget such
idea.
It works just fine. In fact, quite a lot of international calls to smaller
countries are routed exactly that way.
Alex
QoS mechanisms (i.e. CBWFQ/LLQ) take care of prioritizing voice over data.
So I am not worried about data. Dynamic routing (EIGRP in this case) does a
beautiful job of failing over IP traffic from one T1 to another when
required.
The objective of this exercise is to see how we can go about overflowing
voice traffic from the terrestial T1 to the satellite T1. So, this is not
really about load-balancing or load-sharing.
At this time, it looks like using H.323 gatekeeper as suggested by Patrick
Murphy maybe the most likely way to go.
From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On
Behalf Of Stephen Sprunk
Sent: Sunday, March 28, 2004 2:35 AM
With G.729a and cRTP, you can cram over a hundred calls into
<...>
At this time, it looks like using H.323 gatekeeper as suggested by Patrick
Murphy maybe the most likely way to go.
Yes, use gatekeeper to balance calls between terrestrial link (for first NN
calls) and satellite link (for other calls).
Be sure that reverse traffic uses the same path (it can be done by simple
routing).