Diameter Agent Overload and the Peer Overload Report
draft-ietf-dime-agent-overload-11

Below is the OPS DIR review by Will.

** Editorial **

*Section 2, page 4
>    A RFC6733 Diameter Client, an RFC6733 Diameter Server, and
RFC6733
>       Diameter Agent.

s/ RFC6733/ [RFC6733]
Similar changes should also be made in this section to get consistent
with section 1 and the last sentence in section 2(therein you were
using [RFC6733]).


* Section 3.1.1, page 4:

>                              +-+    +-+    +-+
>                               |c|----|a|----|s|
>                              +-+    +-+    +-+

Though I can easily guess what does “c, a, s” mean here, I still
suggest to put full words or at least add a sentence below the figure
to explain.
The same issue should be fixed in all the figures below in entire
section 3.

 
* Section 3.1.2, page 6:

>   In the case where one of the agents in the above scenario becomes
>   overloaded

s/ scenario becomes/ scenarios become

If I understand correctly , here you were referring to two scenarios
above?

>   When the client has an active and a standby connection to the two
>   agents then an alternative strategy for responding to an overload
>   report from an agent is to change to standby connection to active
and
>   route all traffic through the new active connection.

I would suggest to split this sentence in case of misunderstanding.


* Section 3.1.3, page 7:

>  Handling of overload of one or both of agents a11 or a12 in this
case
>   is equivalent to that discussed in section 2.2.

Tried hard to find section 2.2, but there is no such section.


* Section 5.1.1, page 8:

>   When sending a Diameter request a DOIC node that supports the
>    OC_PEER_REPORT feature MUST include in the OC-Supported-Features
AVP
>    an OC-Feature-Vector AVP with the OC_PEER_REPORT bit set.

Full name of AVP should be put into terminology.

(Resending because I forgot one more high-level comment; see at the bottom.)

One rather important comment:
While the security considerations section describes a possible attack, it does not say anything about how to handle this attack and the actually impact this attack might have. Please add more text!

And then some mostly editorial high level comments:
All in all, I had a rather hard time reading this document because it seems on the one hand sightly over-specified and over structured, while not giving very concrete guidance in some cases.

E.g. in section 5.2.5;
 "In the case that the OCS entry validity duration expires or has a
   validity duration of zero ("0"), meaning that if the reporting node
   has explicitly signaled the end of the overload condition then
   abatement associated with the OCS entry MUST be ended in a controlled
   fashion."
   I don't think normative language is needed here because there is no impact of interoperation. But then is does't explain what "in a controlled fashion means". So I wouldn't even know how to implement that MUST correctly.

Another example in section 4:
" In this scenario, when doing abatement on the
   PEER report, the reacting node SHOULD take into consideration the
   number of messages already throttled by the handling of the HOST/
   REALM report abatement."
How to take that into consideration? And why is this normative?

Or here in section 5.2.3:
"When a reacting node receives an OC-OLR AVP with a report type of
   peer it MUST determine if the report was generated by the Diameter
   peer from which the report was received.

   If a reacting node receives an OC-OLR AVP of type peer and the
   SourceID matches the DiameterIdentity of the Diameter peer from which
   the response message was received then the report was generated by a
   Diameter peer."
Why don't you just say the following:
"When a reacting node receives an OC-OLR AVP with a report type of
   peer it MUST determine that the SourceID matches the DiameterIdentity of the Diameter peer from which
   the response message was received."

Also the indentation used is sometimes confusing. In some cases you should probably really use real listings with bullet points.

Please also double-check all normative language: as indicated above there are some cases where the normative language is probably not really needed and there are other cases where an additional upper letter MUST or SHOULD would make things clearer.