[systemd-devel] [PATCH] Added UFD (Uplink failure detection) support to networkd

[Andrei Borzenkov]

On Wed, Jan 28, 2015 at 3:40 PM, Lennart Poettering
<lennart at poettering.net> wrote:
> On Wed, 28.01.15 10:13, Rauta, Alin (alin.rauta at intel.com) wrote:
>
>> Lennart, on a switch I should be able to configure more than one UFD
>> group.
>
> What precisely does this mean? WOuld those groups be orthogonal?
>
> I really would like to avoid introdcuing the "tags" concept for
> now. Would a solution where you give the uplinks appropriate names
> (like "uplink0", "uplinkXYZ", "uplink_waldo" and so on) suffice, when
> you can then refer to them in a .network file you apply to the
> downlinks as "BindCarrier=uplink*"?
>

This has interesting corner case. Let's say you have one interface
uplink0 and one interface downstream0 that has BindCarrier=uplink*. So
we bind downstream0 to uplink0 on startup. Later (online) we add
second interface uplink1 and downstream1 which also has
BindCarrier=uplink*. But now this one is suddenly bound to *two*
interfaces instead of one; so they both behave differently.

Could also happen if interface fails on startup and is hotswaped or
otherwise repaired replaced later.

As such concept of "uplink group" abstracts away direct connection
between down- and upstream. Each operation would then implicitly
iterate over interfaces in group; when new interface is added, it
provides natural place to adjust group monitoring (like set watch for
it etc). Not so easy with your proposal.

> BindCarrier= would take a list of interface names, possibly with
> globs. If you want to up and down a link "foo" if at least one of the
> links "bar", "quux", "piep", "miau1", "miau2" are up, you could write
> this as "BindCarrier=bar quux piep miau*".
>
> What would introducing the "tag" concept give you beyond this very
> simple schreme described above?
>
> Lennart
>
> --
> Lennart Poettering, Red Hat
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