Re: [Dime] Issue#35 conclusion

[Maria Cruz Bartolome <[e-mail]>]

Dear Ulrich,

See comments below please.
Anyway, since during IETF meeting it was commented that this could be considered as an extension, not sure how this should be managed from now on. I presume we should confirm that in this list.

Best regards
/MCruz

From: Wiehe, Ulrich (NSN - DE/Munich) [mailto:[e-mail]]
Sent: jueves, 06 de marzo de 2014 10:12
To: Maria Cruz Bartolome; [e-mail]<mailto:[e-mail]>
Subject: RE: [Dime] Issue#35 conclusion

Dear MCruz,

for my clarification:
what you say about Host reports is also true for Realm-Routed-Request reports. Can you please confirm.
[MCruz] I think this case is different. If we agree that realm reports are only generated by agents (as an aggregated report based on host reports and potentially another implementation dependent criteria), then the server itself does not require a traffic-to-realm reduction, on the contrary, the host only requests a traffic-to-host reduction. Agent may or not (I think this is up in the draft) to  forward back to the original client this host-report. Then, not sure if we really need something else here.
<Ulrich> I don't know whether it is still relevant, but I would have thought that the agent that generates a realm-routed-request report, when taking the host reports received from servers into accout for the aggregation, may e.g. detect that all the severs request reduction of traffic from the same a specific client. Would it not be logical that the aggregated realm-routed-request report in this case also only requests reduction from that client (with the aggregated percentage)? </Ulrich>
[MCruz] This could be something to be considered and could provide some added value, but it is up to interpretation whether this is required.

Proposal b) does not address the 3GPP requirement from TR 29.809 clause 6.4.7.  please confirm.
[MCruz] It does address the 3GPP requirement in general, but not for one specific case:  "There is one special case here, when the agent is acting on behalf of the client (i.e. for a non-supporting client or for an agent SFE with topology hiding)".
<Ulrich> I'm not sure, see below</Ulrich>

Also proposal b)  impacts the reporting node which must not send client specific OLRs (with separate sequence number streams for different clients)
[MCruz] I do not think so. In the case I mentioned, when the agent is acting on behalf of the client, it is always the receiver of the answers (i.e. from a host perspective, the client is the agent
<Ulrich>This is not correct. The host (reporting node) does not know whether the reacting node is the client (identified by orig-host in the request) or an agent (acting on behalf of the client and possibly also on behalf of other clients); the reporting node receives a request that contains an OC-Supported-Features AVP; this indicates to the reporting node that there is a downstream node supporting DOIC. Let me give an example:
Two non-supporting clients C1 and C2 send requests via the same supporting agent A to the server. Traffic from C1 increases, so S requests a 10% throttling from C1 (sequence number 1). As the agent A is acting on behalf of C1, A will do the throttling. As a not wanted but acceptable side effect A will also throttle traffic sent from C2 to S. Now the situation improves and S only requests a 5% reduction from C1 (sequence number 2).  Again A will apply the 5% throttling also for traffic from C2, which again is not nice but acceptable. Now  Traffic from C2 increases (although throttled with 5%) and S request a 50% throttling from C2 (sequence number 1). </Ulrich>
, and then there are not separate sequence number streams).
[MCruz] I think your example is right, and it highlights something important I haven't realized. Since the server may send totally different reduction requests to different clients, as in your example, the key point is not even that they carry different sequence numbers, but that reduction to apply to "all" clients will oscillate a lot, depending on server requests towards one specific client. Then, a way to solve this is that the server knows whether or not an agent is acting on behalf of the final client. If so, reporting node should not request reductions per client (i.e. %reduction will be the same for any client).

Also, shouldn't b) read:
We expect the agent to apply this host type / realm-routed-request type report to any non-DOIC-supporting client that is sending requests towards this host/realm.
[MCruz] Yes, any non-DOIC-supporting client.

Also, you say:
b) does not require any changes to the actual draft

I guess at least some clarification is required as some (Lionel, Nirav, but not Steve)  think it is "natural" and "implicit" that agents would do the per client behaviour as a default.
[MCruz] Agreed, at least clarification is required.

An alternative proposal that addresses the complexity argument for agents but at the same time at least partly addresses the 3GPP requirement would be to make use of a feature flag: clients allways set the flag, agents do not set the flag, reporting nodes may send client specific OLRs when the flag in the request was set. This has no big impact to clients (only always set the feature flag), no impacts to agents, and allows (if so desired) reporting nodes to make use of the client specific throttling (at least in some cases).
<Ulrich>any comments?</Ulrich>
[MCruz] I agree this could be a way for the reporting node to know that an agent is not acting on behalf of a client

Best regards
Ulrich



From: DiME [mailto:[e-mail]] On Behalf Of ext Maria Cruz Bartolome
Sent: Thursday, March 06, 2014 9:00 AM
To: [e-mail]<mailto:[e-mail]>
Subject: Re: [Dime] Issue#35 conclusion



Dear all,

This mail thread started proposing new OLR reports to request reduction for one specific client.
However, the discussion clarified that as it is the draft today, Host-report is sent from a reporting node towards the client from where it receives the request. Then, reduction is requested per client in all cases already.
There is one special case here, when the agent is acting on behalf of the client (i.e. for a non-supporting client or for an agent SFE with topology hiding). In this case, the reporting node sends host-report to agent. Here we have two options:


a)     We expect the agent to apply the host-report received in an answer to specifically the client that sent the corresponding request

This requires some extra complexity at agent side.

But here we have one more option: allow the reporting node to choose whether it prefers to apply this host-report to "all-client" vs "one-client". That increases again the complexity (at reporting node, protocol-wise, and at agent).



b)     We expect the agent to apply this host-report to any client that is sending a request towards this agent

In my opinion, this is the best approach, it reduces complexity and increases robustness.

Therefore, I will be in favor of option b), which does not require any changes to the actual draft.

Let me know your opinions.
Best regards
/MCruz