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IPSEC site-to-site VPN for data and voice?

network_user
Level 1
Level 1

Hello,

I beleive normal IPSEC site-to-site VPN can accomodate data and voip traffic. But I have seen many implementations with IPSEC/GRE implementations for voice over VPN. Why is the need for GRE in this case?

Thank you.

2 Replies 2

Collin Clark
VIP Alumni
VIP Alumni

GRE is typically used when multicast is needed across the tunnel, such as paging or MoH.

Good point raised by Collin.

GRE over IPsec allows you to have one tunnel (IPsec SA) for all traffic, classic IPsec would typically require multiple SAs.

On IOS, GRE allows tunnel protection which is simpler and recommended.

Apart from transporting multicast, GRE can carry any traffic on top IPv4, IPv6, IPX(?)...

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