GRE and VTI

---

# GRE

GRE over IPSec Site-to-Site VPN

Setup ISAKMP as before, adjust Transform-Set and ACL:

```
crypto ipsec transform-set GRE-VPN esp-aes 256 esp-sha256-hmac
    mode transport exit

ip access-list extended GRE-VPN-ACL
    permit gre host <this-pub> host <peer-pub>
  exit

crypto map GRE-CMAP 10 ipsec-isakmp
    match address GRE-VPN-ACL
  set transform-set GRE-VPN
  set peer <peer-pub>
  exit

int g0/0/0
    crypto map GRE-CMAP

int tunnel 1
    bandwith 4000
  ip add 172.16.1.1 255.255.255.252
  ip mtu 1400
  tunnel source <this-pub>
  tunnel destination <peer-pub>
```

# VTI

Configure ISAKMP policy again

```
crypto ipsec transform-set VTI-VPN esp-aes 256 esp-sha256-hmac
    mode tunnel
  exit

crypto ipsec profile VTI-Profile
    set transform-set VTI-Profile
  exit

int tunnel 1
    bandwith 4000
  ip address 172.16.1.1 255.255.255.252
  ip mtu 1400
  tunnel source <this-pub>
  tunnel dest <peer-pub>
  tunnel mode ipsec ipv4
  tunnel protection ipsec profile VTI-Profile
```

# General: further steps

```
router ospf 100
    network 172.16.0.0 0.0.0.3 area 0
```