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If HSS (Home Subscriber Server) acts as a Diameter Client and is sending Accounting Requests (I see in traffic), who acts as a Diameter Server?

asked 08 May '11, 13:59

wired's gravatar image

accept rate: 9%

As I know from studying and book IMS Signalling (by Ericsson), HSS acts as a Diameter Server? Why Client in my trace? :-s

(08 May '11, 14:23) wired

you should know, HSS server can also invoke requests.

like HSS issue RTR to S-CSCF to deregister an identity, PPR to notify profile changes of any identity.

(04 Apr '14, 09:20) Sanny_D

Many Diameter interfaces involve server-initiated exchanges. You see it even in the base protocol spec. A "server" from a Diameter perspective is not strictly defined by the originator of a message, and is usually defined within the context of a given Diameter application. In theory it's even possible for a single Diameter host to be a client for one application and a server for another unrelated application, over the same Diameter peering to an upstream agent.

To your question on who is "serving" the HSS's request, when you consider that Diameter itself is a blanket protocol with many applications running over it, with Diameter "Agents" potentially sitting between end systems, to call anything a "Server" you really need to base that terminology on the specific application you're concerned with, running over top of Diameter.

For example, for Diameter credit control (DCCA, RFC 4006), the state machine logic specifically calls for a Diameter Credit Control "Client" and a Diameter Credit Control "Server", where you are technically correct to say that a "Server" sends the Reauthentication Request (RAR) messages 'ONLY' because the credit control application spec specifically defines it as a "Server".

Or another way to look at it: If you have agents, your client is sending CER messages to an agent directly. Does that make the agent a server? You always have a given requester and answerer, but "Server" is ambiguous unless you give it the context of a specific application and scenario.

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answered 04 Apr '14, 15:16

Quadratic's gravatar image

accept rate: 13%

edited 04 Apr '14, 15:20

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question asked: 08 May '11, 13:59

question was seen: 3,077 times

last updated: 04 Apr '14, 15:20

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