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Is this still the way these days?

Steven Williams
Enthusiast
Enthusiast

I have a layer 3 MPLS where I have multiple sites connected. I have phones at each site, as well as paging and voicemail. 

So because of the paging, Multicast I assume, we have GRE tunnels all over running PIM and creating mroute statements.

Is there no other way to do this these days? Are people doing this because their MPLS providers won't do multicast? Or is it something specific with the Cisco Voice paging platform?

2 REPLIES 2

Mohammad Alhyari
Cisco Employee
Cisco Employee

If the ISP allows multicast then mVPN [multicast vpn is the best to be done there]. Otherwise you need the ISP to have multicast info for all of your inside data groups which is not scalable. As you said GRE is there to provide the overlay tunneling and to hide the multicast from the ISP.

Multicast VPN

https://www.cisco.com/c/en/us/td/docs/ios/12_2s/feature/guide/fs_mvpn.html

It just seems very cumbersome when I have like 100 sites with voip on MPLS and I have these tunnels to administer to all these sites.

I mean if I am going to have that many tunnels I might as well look at canning my MPLS and go to DMVPN since ill need GRE tunnels for that, I could cut some costs on the MPLS side... 

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