Subject: Re: [netlmm] Lack of session indication

From: "Koodli, Rajeev" <[email-masked]>
Date: Mon, 11 Aug 2008 22:29:13 -0400

Hi Sri,

> Lets step back a bit and explore this scenario when we would need
> this.
> 
> a.) MAG deregistered the session
> b.) LMA terminated the session
> c.) LMA rebooted
> 
> For #a, MAG would take out the BUL entry and policy routes fro
> the MN's HNP. So, the LMA should not see this tunneled packet
> and hence no need for additional error message.

[RKo:>] Okay, but the MAG may receive a packet from LMA for the MN. 

> 
> For #b, LMA would send a revocation message to MAG. MAG should
> not be sending tunneled packets. No need for additional error
> message, we already have revocation message.
> 

[RKo:>] Okay.

> For #c, its not session specific. We need either a notification
> message, other mechanism such as restart-counter, or other
> mechanism.
> 

[RKo:>] After LMA reboots, packets can continue to arrive for a MN from
the MAG until the re-start counter cycle syncs up. In order to reduce
this potentially long delay, we defined an error message to be sent
immediately upon recovery (see Unsolicited Node Echo Reply message in
draft-koodli-netlmm-path-and-session-management). This should work, but
not entirely reliable - packets may still arrive for a MN. In such a
case, the LMA informing the MAG is expected to force the MAG to clean up
state and re-issue binding registration. A similar mechanism for 3G
exists - see 3GPP spec TS 23007, Section 10). The node behaviors must be
specified although a mechanism such as Unsolicited Node Echo Reply
(U-NERP) can reduce the chances of receiving packets for a MN without a
BCE. 

What we need is a message from LMA to MAG with "no binding exists for
HoA/HNP or for GRE Keys", which are present in the data packet itself.
We can do that also with a U-NERP message. 

Regards,

-Rajeev

> In what other cases other than the above, the session would magically
> disappear, assuming we solve #c ?
> 
> 
> Sri
> 
> 
> 
> 
> 
> 
> 
> 
> 

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---

From: Hesham Soliman <[email-masked]>
Date: Tue, 12 Aug 2008 13:54:54 +1000

> not entirely reliable - packets may still arrive for a MN.

=> This is an error recovery issue. You really need to study the different
scenarios for this and cover all the failure cases. I think the message is
on the right track but needs to be secure. This should not be done as part
of binding update management because it's an aggregate for all bindings.
Also note that you will need to do this for all MAGs.

Hesham

In such a