gauge/counter

[boucadair]

Please check when it makes sense to use a gauge rather than a counter. For example:

+--ro num-event-avg?     yang:counter32

[fno2010]

Good point. yang:gauge64 seems more reasonable.

[boucadair]

Thanks.

BTW, is there any reason all the counters are 32? may be moved those to be 64.

[fno2010]

Initially, we just thought 32 might be enough for the current deployment. But I agree. 64 will be better. I also think we should use 64.

[boucadair]

Reopening as I think the type has to be reassessed for some other data nodes (e.g., res-mem-size).

If the value may increase/decrease, then gauge64 should be used.

[fno2010]

Yes, you are right. I will check all the statistics data nodes to fix their types.

I think the following nodes should use gauge64 at least:

• memory utilization
• number of living connections
• statistics in the last time window

[fno2010]

Track suggestions from yangdoctors early review by Andy:

5 minute counters

• Should be type gauge64, not counter64 because the value can go down.

  • num-total-last-req
  • num-total-last-succ
  • num-total-last-fail

size counters

• Should be type uint64, not counter64 because the value is a size.

  • res-mem-size
  • res-enc-size

update event counters

• It is not clear what the correct data type should be. Not counter64.

  • num-event-max
  • num-event-min

• Are these leafs maintained over a 5 minute interval perhaps?
  Then they should be gauge64.

• The procedure to determine min and max should be specified or referenced.

[billwuqin]

I suggest to set data type for num-event-max and num-even-min as uint32, we can find some example in RFC8532 and RFC8299.
Regarding time interval, I am wondering whether time-window-size is related to time interval?

[fno2010]

uint should always be safe. But maybe gauge provides more semantics? I think either work.

About the time interval, yes, it is configured by time-window-size. But num-event-* shows the total value, not the value in a given time interval. We just added a collection of stats num-event-*-last to provide values in the last time interval.

[fno2010]

Changed type of num-total-last-* to gauge64:

draft-ietf-alto-oam-yang/yang/ietf-alto-stats.yang

Lines 85 to 102 in 5dea617

	leaf num-total-last-req {
	type yang:gauge64;
	description
	"The total number of ALTO requests received by the server
	within the last time window.";
	}
	leaf num-total-last-succ {
	type yang:gauge64;
	description
	"The total number of successful responses sent by the ALTO
	server within the last time window.";
	}
	leaf num-total-last-fail {
	type yang:gauge64;
	description
	"The total number of failed responses sent by the ALTO
	server within the last time window.";
	}

Changed type of res-*-size to uint64:

draft-ietf-alto-oam-yang/yang/ietf-alto-stats.yang

Lines 129 to 140 in 5dea617

	leaf res-mem-size {
	type uint64;
	units "bytes";
	description
	"Memory size utilized by the information resource.";
	}
	leaf res-enc-size {
	type uint64;
	units "bytes";
	description
	"Size of JSON encoded data of the information resource.";
	}

Changed type of num-event-* to gauge64 (Qin suggests to simply using uint32) and updated the descriptions:

draft-ietf-alto-oam-yang/yang/ietf-alto-stats.yang

Lines 198 to 228 in 5dea617

	leaf num-event-max {
	when 'derived-from-or-self(../../alto:resource-type,'
	+ '"alto:update")';
	type yang:gauge64;
	description
	"The maximum value over the total number of update events sent
	to each connected session. Assume there are 3 connected
	sessions A, B, and C with 4, 3, and 2 update events sent to
	them respectively, the value of this metric is 4. After a
	while, if there is no new update event sent to any session,
	but the session A is disconnected, then the value of this
	metric is updated to 3.";
	}
	leaf num-event-min {
	when 'derived-from-or-self(../../alto:resource-type,'
	+ '"alto:update")';
	type yang:gauge64;
	description
	"The minimum value over the total number of update events sent
	to each connected session. The procedure is similar to
	num-event-max.";
	}
	leaf num-event-avg {
	when 'derived-from-or-self(../../alto:resource-type,'
	+ '"alto:update")';
	type yang:gauge64;
	description
	"The average value over the total number of update events sent
	to each connected session. The procedure is similar to
	num-event-max.";
	}

num-event-*-last are added to provide stats within the last time window:

draft-ietf-alto-oam-yang/yang/ietf-alto-stats.yang

Lines 229 to 266 in 5dea617

	leaf num-event-total-last {
	when 'derived-from-or-self(../../alto:resource-type,'
	+ '"alto:update")';
	type yang:gauge64;
	description
	"Total number of update events sent to all the connected
	sessions within the last time window.";
	}
	leaf num-event-max-last {
	when 'derived-from-or-self(../../alto:resource-type,'
	+ '"alto:update")';
	type yang:gauge64;
	description
	"The maximum value over the number of update events sent
	to each connected session within the last time window. The
	procedure is similar to num-event-max, but only count the
	update events within the last time window.";
	}
	leaf num-event-min-last {
	when 'derived-from-or-self(../../alto:resource-type,'
	+ '"alto:update")';
	type yang:gauge64;
	description
	"The minimal value over the number of update events sent
	to each connected session within the last time window. The
	procedure is similar to num-event-max, but only count the
	update events within the last time window.";
	}
	leaf num-event-avg-last {
	when 'derived-from-or-self(../../alto:resource-type,'
	+ '"alto:update")';
	type yang:gauge64;
	description
	"The average value over the number of update events sent
	to each connected session within the last time window. The
	procedure is similar to num-event-max, but only count the
	update events within the last time window.";
	}