How could I check if the remote tunnel is ip with configuration
ip address 192.168.1.1 255.255.255.252
tunnel source FastEthernet0/0
tunnel destination 220.127.116.11
sh ip int tunnel0 ( shows up )
ping 192.168.1.2 source fa 0/0 ( can ping )
Are there any other commands which can help in troublshooting tunnels / network reachability
What are the disadvantages of using this setup compared to IPSEC ( apart from security )
What is the other best option to have when IPSEC is not allowed.
if both ends support it you can use GRE keepalives to detect the good state of the other side
the command can be
keepalive 10 3
or you can run a routing protocol over the tunnel GRE ip subnet
router ospf 10
network 192.168.1.0 0.0.0.3 area 0
both methods provide a way to detect peer and overall path state.
Often GRE tunnel is transported into IPsec for protection.
this is handy because the definition of traffic to be protected is made with a single line ACL GRE between public ip addresses hosts
if IPSec cannot be used you can use GRE alone as described above.
Hope to help