GRE tunnels

carl_townshend · ‎03-23-2007

Hi all, what is the benifit of using these ? and do people still use them ?

achalante · ‎03-27-2007

yeah..people still use them. Just like its name implies, it's used as a tunnel so as to allow protocols run across a network that ostly wouldnt support that particular protocol. e.g,...it can be used to run IPv6 over IPv6 and vice versa,...you can use it to run routing protocols across others e.g ospf over eigrp. And imagine a scenario in an ospf network, say you have to connect area 2 to area 0,..but area 2 has to go through area to get to area 0, but unfortunately, area 1 is a stub network...in this case, the use of virtual-links would be totally impossible, and the best way out would be to use a GRE tunnel. I hope this helps.

Danilo Dy · ‎03-27-2007

I use it in the following;

- TELCO MPLS Service. This will make me control the routing between remote sites over MPLS service, not my TELCO MPLS provider which some charge per routing change and it takes sometime for them to make the necessary routing change (not to mention human error on the TELCO side).

- Internet/ISDN/Leased Line. I use it in the internet (GRE Tunnel over IPSEC) to make use of internet for auto-failover to ISDN, or Leased Line to auto-failover to GRE Tunnel over IPSEC.

Some people use it to route other protocol over it (i.e. IPX) or IPv6.

You can actually find a lot of use of IP GRE Tunnel that will save you cost, enhance routing performance, ease of management.