Zte ZXR10 ZSR V2 Series - Gre Vpn; L2 Tp Vpn; Figure 3-1 Ipsec NAT Traversal Schematic Diagram

ZXR10 ZSR V2 Series Router Product Description
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Figure 3-1 IPSec NAT traversal schematic diagram
3.5.3 GRE VPN
Generic Routing Encapsulation (GRE) protocol can encapsulate the packets of some
network-layer protocols so that these encapsulated packets can be transmitted in the IPv4
network.
When a router receives an original packet (payload) to be encapsulated and routed, the
payload was first encapsulated by GRE into a GRE packet which is encapsulated by the
IP protocol and then is forwarded at the IP layer. The original packet protocol is called the
passenger protocol, the GRE the encapsulation protocol and the IP protocol the delivery
protocol or transport protocol. It should be noticed that the above processes do not care
about the specific format or content of the passenger protocol.
GRE has the following advantages:
 A multiprotocol local network can transport packets via a single-protocol backbone
network.
 Connect discontinuous subnets to create VPN.
 Expand network scope of work, including the protocol with limited route gateways.
3.5.4 L2TP VPN
L2TP (Layer 2 Tunneling Protocol) is a L2 tunnel protocol based upon point-to-point
protocol PPP. L2TP mainly consists of LAC (L2TP Access Concentrator) and LNS