[ovs-discuss] OVSDB connection keep-alive vs. echo RPC

Roman Bolshakov roolebo at gmail.com
Thu Dec 7 18:38:35 UTC 2017


Couple years ago I implemented my own lib for OVSDB. It had one
communication thread that replied on the echoes as well as sent management
commands from the application. Something very similar of what you're
thinking to implement but based on python coroutines.

Built-in Python lib is different and talks to wire in the application
thread. It replies to probes over TCP but doesn't send them over Unix
socket. OVSDB drops a client that doesn't reply a probe. So in case of TCP,
it reconnects after a user send a request to process a Transaction.

As far as I understand echo request/replies work better for a local/remote
OVS controller that needs full awareness of database state and all changes
within it. Indeed, OVN Southbound (as OVS controller) uses it like that.

IMO, for management operations outside of an OVS controller, It's simpler
to avoid separate thread with probe replies as additional IPC is needed
between threads.

чт, 7 дек. 2017 г. в 20:25, Matt Layher via discuss <
ovs-discuss at openvswitch.org>:

> Hi all,
>
> I'm working on implementing an OVSDB client in Go
> (https://godoc.org/github.com/digitalocean/go-openvswitch/ovsdb) and
> recently implemented the Echo RPC.
>
> https://tools.ietf.org/html/rfc7047#section-4.1.11
>
> According to the RFC, the purpose of Echo is "to verify the liveness of
> a database connection".  Does this mean that Echo should be used as a
> keep-alive of sorts for long-running connections?  I'm thinking about
> adding a background loop to my client that sends Echo RPCs at a regular
> interval for this purpose.
>
> Next, if I were to connect to ovsdb-server via TCP instead of UNIX
> socket, would enabling TCP keep-alives serve the same purpose?
>
> If neither of these approaches are necessary, it'd avoid adding some
> additional complexity to the code.  I'd be very curious to hear what
> folks have done.
>
> Thanks for your time,
>
> Matt Layher
>
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