Re: [MEXT] [WGLC] draft-ietf-mext-flow-binding-03

[George Tsirtsis <tsirtsis at googlemail.com>]

On Mon, Oct 26, 2009 at 8:58 AM, Hesham Soliman
<hesham at elevatemobile.com> wrote:
> Yuri,
>
>
>>
>> After the text:
>>
>> "1 Discard.  This value indicates a request to discard all packets
>>  in the flow described by the option.  No BIDs are associated with
>>  this Action."
>>
>> Add the following text:
>>
>> "In the case there is no correspondent FID to a particular flow or range of
>> flows, which should be discarded, a mobile node MUST install a correspondent
>> FID, otherwise error code 136 "FID not found" will be returned by HA.
>
> => I don't understand what this means. Can you clarify?
>

GT> Yes this seems strange since there is no way to indicate Discard
Action without providing an FID.

>
>  Care
>> should be taken when issuing request for discarding packets as this will lead
>> to disrupting applications communication after the "Discard" action was
>> applied to selected flows. Implementations may consider notifying impacted
>> applications in mobile nodes"
>
> => This part is clear to me.
>

GT> Yuri, I will add this to the document, no problem.

> Hesham
>
>>
>>
>>
>> Regards
>> Yuri
>>
>>
>> -----Original Message-----
>> From: George Tsirtsis [mailto:tsirtsis at googlemail.com]
>> Sent: Friday, October 23, 2009 5:54 PM
>> To: Yuri Ismailov
>> Cc: Laganier, Julien; mext at ietf.org
>> Subject: Re: [MEXT] [WGLC] draft-ietf-mext-flow-binding-03
>>
>> Hi Yuri, comments inline.
>>
>> On Fri, Oct 23, 2009 at 1:20 PM, Yuri Ismailov <yuri.ismailov at ericsson.com>
>> wrote:
>>> Hi Goerge,
>>> Thanks for the answers,
>>> What I did not understand if there will be some clarification text in the
>>> draft around "discard" action or all that is obvious and does not require any
>>> changes? My comment was that some additional text is needed.
>>>
>>
>> GT> I am not yet sure what non-trivial clarification we can provide.
>> IMO we do not need to provide any further clarifications on this subject.
>>
>>> I do not think your clarification about using FID-PRI is quite clear. The
>>> reason is that there is no FID for a particular flow within the range There
>>> is only a FID for the whole range of port numbers and/or IP addresses.
>>>
>>
>> GT> What prevents you from  creating another FID that is specific for that
>> flow?
>>
>>> Surprized that disclaimer for n-cast about carefull use is in the text
>>> and about disclaimer for "discard" you just say "I do not think there is
>>> anything to say here." Still the question is will there be related text?
>>>
>>
>> GT> I think the implication of dropping packets is much clearer than
>> the implication of n-casting. Dropping packets means the application to which
>> the packet is sent will not receive the packet...do we really need to say
>> that? On the other hand, receiving N copies of the same packet has some
>> implications to TCP....this is also rather obvious for people that know
>> TCP...but maybe not everyone does.
>>
>>> Regards
>>> Yuri
>>>
>>>
>>> -----Original Message-----
>>> From: George Tsirtsis [mailto:tsirtsis at googlemail.com]
>>> Sent: Friday, October 23, 2009 11:08 AM
>>> To: Yuri Ismailov
>>> Cc: Laganier, Julien; mext at ietf.org
>>> Subject: Re: [MEXT] [WGLC] draft-ietf-mext-flow-binding-03
>>>
>>> Hi Yuri,
>>>
>>> Comments inline...
>>>
>>> On Tue, Oct 20, 2009 at 8:55 AM, Yuri Ismailov <yuri.ismailov at ericsson.com>
>>> wrote:
>>>> Hi,
>>>> after re-reading the draft come up with the comment on "Discard"
>>>> action in "Flow Identification Mobility Option"
>>>> I suggest either to extend the paragraph in the section 4.2 or add a
>>>> separate subsection clarifying behavior of MN and HA before and after
>>>> the "Discard" action was issued by MN.
>>>>
>>>> Below are the issues which are proposed to be addressed in the text.
>>>>
>>>> 1.The case when installed FID represent ranges of port numbers and IP
>>>> addresses. If MN decides to discard a particular flow within the
>>>> range then before that a correspondent FID should be installed in the HA.
>>>> Otherwise
>>>> "136 FID not found" will be returned from HA.
>>>>
>>>
>>> GT> If the MN wants to discard a particular flow within a range of
>>> previously registered flows, it needs to either split the range it two parts,
>>> or even better, use a higher FID-PRI for the  discard flow so that packets
>>> get matched against it before they get matched against the range.
>>>
>>>> 2. Specify the time interval for how long time the "Discard" state
>>>> will be active in HA. This is necessary because there is no
>>>> "un-discard" message sent from MN.
>>>>
>>>
>>> GT> Flow bindings share the same lifetime with the BU. There is no
>>> flow binding-specific lifetime. If an MN wants to remove a flow binding it
>>> sends a BU which does not include the corresponding FID.
>>>
>>>> 3. Add a disclaimer that for some protocols, like TCP, "Discard"
>>>> action may lead to hanging up the connection at CN and should be used
>>>> responsibly.
>>>>
>>>
>>> GT> Discarding packets will drop connections....yes...I do not think
>>> there is anything to say here.
>>>
>>>>
>>>> Regards
>>>> Yuri
>>>>
>>>>
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>>>>
>>>
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