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What is the difference between GRE over IPsec and IPsec over GRE?
In IPsec over GRE IPsec encryption is done on tunnel interfaces. The end user systems detects data flows which need to be encrypted on tunnel interfaces. An ACL is set to match data flows between two user network segments. IPsec over GRE removes the additional overhead of encrypting the GRE header.
Does IPsec use GRE?
Normally IPsec transport mode is only used when another tunnelling protocol (like GRE) is used to first encapsulate the IP data packet, then IPsec is used to protect the GRE tunnel packets….GRE vs IPSec : Comparison Table.
| PARAMETER | GRE | IPSec |
|---|---|---|
| Standard | GRE is defined in RFC 2784 standard | IPSEC ESP is defined in RFC2406 |
Does GRE over IPsec support multicast?
IPsec cannot encapsulate multicast, broadcast, or non-IP packets, and GRE cannot authenticate and encrypt packets.
What is IPSec GRE tunnel?
IP Security (IPSec) Virtual Private Networks (VPNs) and Generic Routing Encapsulation (GRE) tunnels are both methods for transferring data across public, intermediary networks, such as the Internet. A VPN enables a company to securely share data and services between disparate locations at minimal cost.
Are there service policies on GRE tunnel interfaces?
Note: Service Policies are not supported on tunnel interfaces on 7500. Cisco IOS Software Release 11.3T introduced GRE Tunnel Marking and DSCP or IP Precedence Values, which configures the router to copy the IP precedence bit values of the ToS byte to the tunnel or GRE IP header that encapsulates the inner packet.
What kind of encapsulation protocol is GRE?
GRE is an encapsulation protocol supported by IOS and defined in RFC 1702 . Tunneling protocols encapsulate packets inside of a transport protocol.
How does GRE tunnel marking work on Cisco router?
Cisco IOS Software Release 11.3T introduced GRE Tunnel Marking and DSCP or IP Precedence Values, which configures the router to copy the IP precedence bit values of the ToS byte to the tunnel or GRE IP header that encapsulates the inner packet. Previously, those bits were set to zero.