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CIsco IP Telephony+MPLS backbone


We are small business based in Philadelphia,PA. We are adding another location and decided to consider Cisco VOIP solution. Following are questions are remained unanswered for me.

1. Does MPLS backbone works with VOIP network?

2. For you guys who has Cisco VOIP deployed what kind of Backbone networks you have(considering multiple sites)

3. What do you use for back-up, i am thinking ISDN wouldnt help

4. Any piece of suggestions with the carriers, i am considering SPRINT,ATT,Global crossing, MCI.

Any suggestions are appreciated.



Re: CIsco IP Telephony+MPLS backbone

1. very good choice to use MPLS, as qos marked on packets may be carried over the mpls cloud. Make sure you have all that written into your SLA.

2. I have seen people using a lot of MPLS clouds off late to network sites together with VOIP on top of it. In the past Frame-relay and leased lines were popular. I have also seen some using Metro ethernets. This is usually limited to the same metroplex.

3. ISDN (BRI) is not a good idea for VOIP, due to bandwidth limitation. You may used a low bandwidth frame circuit, low bandwidth MPLS link or a leased line for backup (depending upon location). People do use VPNs as backup these days, but remember there is no guaranteed qos if using VOIp over VPN.

4. I dont want to get into a carrier preference discussion here. I will let that for others to answer!


PS: please remember to rate posts!

Super Bronze

Re: CIsco IP Telephony+MPLS backbone

Just to elaborate on point 3 - lots of people run VoIP over their main WAN i.e. MPLS.

If you have a backup solution that doesn't support QoS, then when running on the backup circuit you can block VoIP signalling traffic on the backup, to force it to fail back to SRST. This will give you basic calling functionality when there is a failure (in fact, more than basic with the new SRST4.0).



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Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

Re: CIsco IP Telephony+MPLS backbone

Guys thanks for your response,

So i am little convinced to do some research as MPLS backbone. Another questions which i am looking answers for are

1. Basically we will be having two sites, both 2 miles apart, how many exit points to the INternet needed. In other words, does both the locations needed to be connected to the internet?

Hall of Fame Super Silver

Re: CIsco IP Telephony+MPLS backbone

You actually going to implement MPLS for 2 locations? Unless you are going to grow it will not provide any ROI, you would be a lot better off going with Metro-ethernet where you will get a lot more bandwidth. MPLS resolves the Frame-Relay hub-spoke topology issues and is cheaper than going full mesh Frame Relay, so it is an excellent solution for multiple-site deployment. If the 2 sites are only 2 miles apart and if you are planning on adding new sites in the area you should look into Metro-ethernet solution.

On the backup note, I completely agree with Aaron, I always purposly block SCCP traffic on the engress ISDN links not to allow the phones to register with CCM over it. If you allow it you'll have alot of complaints about slow dial-tone, bad voice quality, etc. You will be much better off with SRST.


New Member

Re: CIsco IP Telephony+MPLS backbone

You are right on the money with using MPLS for Voice. The great thing is you now have a QoS enabled network that will serve voice better.

You can do the regular IP back bone using Frame Relay, ATM or so, but MPLS offers a better approach.

SRST routers can be used for backup, but only a limited number of telephony features. When you talk about backup, what do you mean? Back up for Call routing?


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