tunnel point to point vs physical point to point

If you have 2 systems on a point to point link you would address them
by a /30 block? When creating 'gre' tunnel you can use /32 for example
ip addr add 1.0.0.1 peer 1.0.0.2 dev mydev.

why can't /32 of arbitray addressing be used on a point to point
between 2 systems?

Hello,

jasonsig a écrit :
> If you have 2 systems on a point to point link you would address them
> by a /30 block?

No, this would be a waste of address space.

> When creating 'gre' tunnel you can use /32 for example
> ip addr add 1.0.0.1 peer 1.0.0.2 dev mydev.

Correct. The local and remote addresses do not even have to be next to
each other.

> why can't /32 of arbitray addressing be used on a point to point
> between 2 systems?

It can.

Hi,
If the point to point systems were for example internet routers, the 2
p2p address would obviously have to be valid address?

Anyway below is a snipit of my gre tunnel script. There are 16 gre
systems on a duel full mesh ospf/gre/ipsec configuration.

I used arbitrary ptop addressing for the tunnel interfaces. Would this
be a good thing?

ip tunnel add net16to14a mode gre remote 172.16.x.14 local 172.16.x.16
ttl 255
ip link set net16to14a up
ip addr add 1.16.14.1 peer 1.14.16.1 dev net16to14a
ip tunnel add net16to14b mode gre remote 192.168.14.x local 192.168.3.x
ttl 255
ip link set net16to14b up
ip addr add 1.16.14.2 peer 1.14.16.2 dev net16to14b

ip tunnel add net16to15a mode gre remote 172.16.x.15 local 172.16.x.16
ttl 255
ip link set net16to15a up
ip addr add 1.16.15.1 peer 1.15.16.1 dev net16to15a
ip tunnel add net16to15b mode gre remote 192.168.15.x local 192.168.3.x
ttl 255
ip link set net16to15b up
ip addr add 1.16.15.2 peer 1.15.16.2 dev net16to15b




Pascal Hambourg wrote:
> Hello,
>
> jasonsig a écrit :
> > If you have 2 systems on a point to point link you would address them
> > by a /30 block?
>
> No, this would be a waste of address space.
>
> > When creating 'gre' tunnel you can use /32 for example
> > ip addr add 1.0.0.1 peer 1.0.0.2 dev mydev.
>
> Correct. The local and remote addresses do not even have to be next to
> each other.
>
> > why can't /32 of arbitray addressing be used on a point to point
> > between 2 systems?
>
> It can.