Subject: [Dime] question on Fail-over

From: <[email-masked]>
Date: Wed, 13 Sep 2006 14:41:28 +0530

Hi,
I have a question on behavior of server at the time of Fail-over of a
client. I will try to explain my doubt with the help of following
scenario. 
            1. Assume that there are two diameter client Nodes, one
configured as ACTIVE and other as STANDBY. Similarly there are two
server Nodes configured.
            2. There are some active sessions (either authorization or
accounting) are on going between ACTIVE Client Node and ACTIVE server
Node. According to RFC 3588, all the messages in these sessions will
have Origin-Host as say, 'active.example.com' and Session-Id AVP as
'active.example.com; <mailto:[email-masked];%3c32> XXXX;YYYY'. 
            3. While there are active sessions, suppose ACTIVE client
Node goes down, and the STANDBY starts to take over the sessions and
tries to send messages to server.
My doubt is:
            In step 3, when STANDBY client starts handling the ACTIVE
sessions, what will be the session-Id AVP? Will it be
'standby.example.com;XXXX;YYYY' ,since this time messages are originated
from the STANDBY client. or will it be the same as
previous('active.example.com; <mailto:[email-masked];%3c32>
XXXX;YYYY'). If it is first one, is it allowed at server Node? I think
the server considers this as an error, since with in the same session
messages with two different Session-Id AVPs are not allowed. If it is
second one, then the Origin-Host AVP (in this case standby.example.com)
will be different than in the host-identity portion of the session-Id
AVP and I think this is not allowed according Base RFC. So, What will be
behavior at server Node in this scenario. 

Any feed back/response is highly appreciated.

Thanks
PRASAD.
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---

From: "Tolga Asveren" <[email-masked]>
Date: Wed, 13 Sep 2006 09:14:24 -0400

Prasad,

I would say the second one. The session-Id for a single session must stay
the same and session-Id must be globally unique. I don't see a reason, why
those principles would be violated with the second option.

    Thanks,
    Tolga

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Wednesday, September 13, 2006 5:11 AM
To: [email-masked]
Subject: [Dime] question on Fail-over

Hi,
I have a question on behavior of server at the time of Fail-over of a
client. I will try to explain my doubt with the help of following scenario.
            1. Assume that there are two diameter client Nodes, one
configured as ACTIVE and other as STANDBY. Similarly there are two server
Nodes configured.
            2. There are some active sessions (either authorization or
accounting) are on going between ACTIVE Client Node and ACTIVE server Node.
According to RFC 3588, all the messages in these sessions will have
Origin-Host as say, 'active.example.com' and Session-Id AVP as
'active.example.com;XXXX;YYYY'.
            3. While there are active sessions, suppose ACTIVE client Node
goes down, and the STANDBY starts to take over the sessions and tries to
send messages to server.
My doubt is:
            In step 3, when STANDBY client starts handling the ACTIVE
sessions, what will be the session-Id AVP? Will it be
'standby.example.com;XXXX;YYYY' ,since this time messages are originated
from the STANDBY client. or will it be the same as
previous('active.example.com;XXXX;YYYY'). If it is first one, is it allowed
at server Node? I think the server considers this as an error, since with in
the same session messages with two different Session-Id AVPs are not
allowed. If it is second one, then the Origin-Host AVP (in this case
standby.example.com) will be different than in the host-identity portion of
the session-Id AVP and I think this is not allowed according Base RFC. So,
What will be behavior at server Node in this scenario.

Thanks
PRASAD.

---

From: <[email-masked]>
Date: Wed, 13 Sep 2006 21:36:24 +0530

Hi Tolga,
According to section 8.8 in Base RFC, the session-Id MUST start with
diameter Identity. I think this is nothing but the value in the
Origin-Host AVP. So we consider the second option as allowed, don't this
differ the section 8.8? Or in this particular scenario, since the sever
knows that active client is down and it should be ready to receive the
messages from standby (with mandatory portion of the session-Id starting
with active client's Identity)?

But in general, I feel the mandatory portion of the session-Id AVP
should be
Same as the value in the origin-Host AVP.

Thanks
Prasad. 

-----Original Message-----
From: Tolga Asveren [mailto:[email-masked]] 
Sent: Wednesday, September 13, 2006 6:44 PM
To: [email-masked]
Subject: RE: [Dime] question on Fail-over

Prasad,

I would say the second one. The session-Id for a single session must
stay
the same and session-Id must be globally unique. I don't see a reason,
why
those principles would be violated with the second option.

    Thanks,
    Tolga

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Wednesday, September 13, 2006 5:11 AM
To: [email-masked]
Subject: [Dime] question on Fail-over

Hi,
server
Node.
Node
previous('active.example.com;XXXX;YYYY'). If it is first one, is it
allowed
at server Node? I think the server considers this as an error, since
with in
standby.example.com) will be different than in the host-identity portion
of
the session-Id AVP and I think this is not allowed according Base RFC.
So,

Thanks
PRASAD.

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9/12/2006

---

From: "Tolga Asveren" <[email-masked]>
Date: Wed, 13 Sep 2006 12:30:13 -0400

Hi Prasad,

I would think 8.8 mentions it just a way to guarantee the globally
uniqueness of the Session-Id. In the scenario you described if you use the
existing session-Id, that property is still there. It is not so that one
host is using another ones id for the session-Id it generates, but it simply
takes over ownership of an existing session.

In general I agree with you that each host should use its own id when
generating new session-Ids, but in the sceanrio we are discussing, the
session is not newly created by the standby host.

   Thanks,
   Tolga

> Sent: Wednesday, September 13, 2006 12:06 PM
> To: 'Tolga Asveren'; [email-masked]

---

From: Anders Kristensen <[email-masked]>
Date: Wed, 13 Sep 2006 13:23:28 -0400

I agree with Tolga and would add that it's probably a very bad idea for 
the server to make any assumptions about the Session-Id, including that 
the FQDN part euals the Origin-Host, even in the session initiating 
request. IMHO, it should be treated just as an opaque ID.

Anders