# Overview

E Series routers support static IP tunnels. An IP tunnel is a virtual point-to-point connection between two routers. See Figure 19. To establish an IP tunnel, you specify a tunnel type and name, and then configure an interface on each router to act as an endpoint for the tunnel.

Figure 19: IP Tunneling

E Series routers support the following types of IP tunnels:

- Generic Routing Encapsulation (GRE) tunnels
- Distance Vector Multicast Routing Protocol (DVMRP) tunnels, also known as IP-in-IP tunnels

## GRE Tunnels

GRE encapsulates IP packets to enable data transmission through an IP tunnel. The resulting encapsulated packet contains a GRE header and a delivery header. Consequently, the packet requires more processing than an IP packet, and GRE can be slower than native routing protocols.

GRE tunnels can be secured with IPSec. See Securing L2TP and IP Tunnels with IPSec .

## DVMRP Tunnels

DVMRP tunnels allow the exchange of IP multicast traffic between routers separated by networks that do not support multicast routing. For information about DVMRP, see Configuring IPv4 Multicast in JunosE Multicast Routing Configuration Guide.

DVMRP tunnels can be secured with IPSec. See Securing L2TP and IP Tunnels with IPSec .