Cannot add scope: link route to interface

[Fabian]

I want to add a link local route to an interface.
Config looks like this:
network:
    ethernets:
        ens192:
            addresses:
            - 172.16.4.131/24
            optional: true
            routing-policy:
                - from: 172.16.4.0/24
                  table: 200
            routes:
                - to: 0.0.0.0/0
                  via: 172.16.4.1
                  table: 200
                  metric: 1
        ens224:
            addresses:
            - 10.0.0.31/24
            gateway4: 10.0.0.1
            optional: true
    version: 2

Unfortunately this means I cannot reach 172.16.4.0/24

I now add this route to ens192:

                - to: 172.16.4.0/24
                  scope: link
                  metric: 1

But netplan apply fails with: "unicast route must include both a 'to' and 'via' IP"
How should i give a "via" to a route with the scope link?

[Fabian (rtech)]

Also when using scope: link the "table" option is ignored.

[Daniel Axtens (daxtens)]

Hi Fabian,

I've seen this too in synthetic testing so setting to 'Confirmed'. (I haven't checked if the table option is ignored but I think that might be a kernel-level limitation rather than a netplan one - can you get it to work with ip 'route'?)

I'm not 100% sure I understand your setup, is the 'on-link' keyword an option as an alternative to a link-scoped route?

Regards,
Daniel

[Fabian (rtech)]

I am using a script with networkd-dispatcher now:
/sbin/ip route add table 200 172.16.4.0/24 dev ens192
This correctly adds the route to the table 200.

AFAIK on-link does specify that the route should be added even when the "via" is not in the same subnet as the address. So this would not apply to my case.

[Daniel Axtens (daxtens)]

Hi,

It looks like we've also seen this reported in LP: #1777681.

I think that duplicates your issue netplan apply failing with: "unicast route must include both a 'to' and 'via' IP". That has also had a fix committed in https://github.com/CanonicalLtd/netplan/pull/33

So I think we're just left with your issue with "Also when using scope: link the "table" option is ignored."

Regards,
Daniel