A GRE tunnel will essentially encapsulate traffic into another packet with the IP of the source interface and destination interface (the tunnel ends).... thereby making the packet look basically liek the routers are talking to one another. This allows you to pass traffic that may otherwise not operate properly.
We have a VPN tunnel between 2 pixes. We us eigrp and IPX in our environment. IPSec does not encrypt IPX nor will the pix route the multicast EIGRP router updates. I built a gre tunnel to pass all the traffic... effectively masking the traffic to look like a standard tcp packet...
I would say that there are similarities between VPN and GRE. They are both based on the concept of tunneling. They both configure a relationship with a remote peer who terminates the tunnel established on the local router. They both take a packet as payload and encapsulate it with new headers.
Those are some of the similarities. The big difference is that VPN is based on IPSec and protects the traffic being transitted while GRE transmits without protecting its payload.
GRE is a tunneling protocol that was originally developed by Cisco, as Marty said at first reply it can be used to transport some traffic that they can't transport over some network for example multicast traffic,IPv6,IPX,AppleTalk and ...
especialy when you're going to transport those traffic over internet (TCP/IP) or when you can't transport data explicitly.
it's an unencrypted tunneling protocol and so simple to implement, in fact when you Interested in to transport ip traffic via GRE, each ip packet becomes the payload of the new ip tunnel packet.
Question We run asr9001 with XR 6.1.3, and we have a very long delay to
login w/ SSH 1 or 2 to the device compare to IOS device. After
investigation, the there is 1s delay between the client KEXDH_INIT and
the server (XR) KEXDH_REPLY. After debug ssh serv...
Introduction The purpose of this document is to demonstrate the Open
Shortest Path First (OSPF) behavior when the V-bit (Virtual-link bit) is
present in a non-backbone area. The V-bit is signaled in Type-1 LSA only
if the router is the endpoint of one or ...
Hi, I am seeing quite a few issues with patch install and wanted to
share my experience and workaround to this. Login to admin via CLI, then
access root with the “shell” command Issue “df –h” and you’ll probably
see the following directory full or nearly ...