IP Allocations for Multi Site GRE VPN Tunnels

[J001]

Hell0,

I am trying to configure GRE VPN Tunnels between 10 sites with EIGRP. This will be a fully meshed VPN.

Is it better to use /30 or /27 ip addressing.

Regards,

 

[brianinms]

You would be better off with a DMVPN or GETVPN.

 

[J001]

Thank you but I am looking to do a manual configuration on routers.

 

[dgrizzard]

Not sure why you would want to do manual configuration as DMVPN is definitely the way to go.

But if you do, then a /31 is what you should use. Maximize the amount of IP addresses and it is easier to deal with.

 

[J001]

I am not sure I understand... The GRE tunnels create a point to point link from one site to another... ?

 

[dgrizzard]

Yes, a GRE tunnel is a point to point connection; unless you use something like DMVPN.

The basics of DMVPN are:

1) You have 1 or more hub sites, then you have spoke sites

2) The spoke sites connect to the hub

3) If a spoke site needs to talk to another spoke site the hub will enable the two spokes to talk directly without going through the hub and wasting bandwidth

This is a very simple explanation of it and there is a lot going on there, but that is the basics.

 

[J001]

How much does this software cost ?

I assume its software that does the configuration for you ?

 

[dgrizzard]

It is a feature in Cisco routers, but you must have the right software version and router model.