Re: [CCAMP] Question on LSP control in draft-ietf-ccamp-mpls-tp-rsvpte-ext-associated-lsp-04.txt

[[e-mail]]

Hi Rakesh

According to the descriptions in RFC3473, I am afraid both the upstream 
notification and downstream notification are permitted.

Some other issues that need to be discussed are tagged in line with <fei> 

Best regards

Fei



"Rakesh Gandhi (rgandhi)" <[e-mail]> 
2012-09-11 21:22

收件人
Lou Berger <[e-mail]>
抄送
"[e-mail]" <[e-mail]>, "[e-mail]" 
<[e-mail]>
主题
RE: Question on LSP control in 
draft-ietf-ccamp-mpls-tp-rsvpte-ext-associated-lsp-04.txt






Hi WG,

Any thoughts on the following proposal?

Thanks,
Rakesh


-----Original Message-----
From: Rakesh Gandhi (rgandhi) 
Sent: Tuesday, September 04, 2012 1:36 PM
To: 'Lou Berger'
Cc: [e-mail]; [e-mail]
Subject: RE: Question on LSP control in 
draft-ietf-ccamp-mpls-tp-rsvpte-ext-associated-lsp-04.txt


Thanks Lou for your reply.

RFC 3473 defines procedures for NOTIFY request and reply. We could use 
this for reverse LSP signaling error notification to the initiating 
ingress node.

<Notify message> ::= <Common Header> [<INTEGRITY>] [ [<MESSAGE_ID_ACK> | 
<MESSAGE_ID_NACK>] ... ]
<ERROR_SPEC> 
<notify session list ::= <upstream session> <downstream session>  >

There are multiple ways we can use the NOTIFY message.

Method 1 - Mid-point aware with Path message request:
When an egress node receives a Path message with REVERSE_LSP object, the 
node will insert NOTIFY_REQ message in the reverse LSP path message with 
node ID of the initiating ingress node. A mid-point node will send  a copy 
of the signaling error to the initiating node using the NOTIFY message.

<fei>Ok, can you clarify which session the copied NOTIFY message are 
carrying? the forward session1 or the reverse session2?
 
If it is session1, I am afraid that the NOTIFY_REQ object is also needed 
in the forward LSP Path message ( "Note that a Notify message MUST NOT be 
generated unless an appropriate Notify Request object has been received." 
copied from paragraph 4.3.2 from RFC3473 )
 
 If it is session2, there is no copied NOTIFY message.

IPv4 Notify Request Object
   IPv4 Notify Node Address: 32 bits
      The IP address of the node that should be notified when generating 
an error message.


Method 2 - Mid-point aware with Resv message request:
When an initiating ingress node receives a Path message for a reverse LSP, 
the node will insert NOTIFY_REQ message in the reverse LSP Resv message 
with its own node ID. A mid-point node will send a copy of the signaling 
error to the initiating node using the NOTIFY message.

<fei> See above, if it is session2, no copied NOTIFY message also.

Method 3 - Tail-end relaying :
When an egress node receives a Path message with REVERSE_LSP object, the 
node will relay the received signaling error message on the reverse LSP to 
the initializing ingress node. The egress node copies the received 
"ERROR_SPEC" object into a NOTIFY [RFC3473, section 4.3] message and 
signals it to the ingress node. In this case, NOTIFY_REQ message is not 
required. 

<fei> I am afraid NOTIFY_REQ object is also required in the forward and 
reverse LSP's Path or Resv message, otherwise ,the egress node will not 
realy the error message.

Please advise your thoughts.

Thanks,
Rakesh



-----Original Message-----
From: Lou Berger [mailto:[e-mail]] 
Sent: Tuesday, September 04, 2012 11:35 AM
To: Rakesh Gandhi (rgandhi)
Cc: [e-mail]; [e-mail]
Subject: Re: Question on LSP control in 
draft-ietf-ccamp-mpls-tp-rsvpte-ext-associated-lsp-04.txt

As I read the current rev, no such notification mechanism is specified.
 Looks like you get to propose one!

Lou (as WG participant).

On 8/31/2012 9:49 AM, Rakesh Gandhi (rgandhi) wrote:
> Hi Lou, Fei,
> 
> When an (originating) ingress node is provisioned with "5 (TBD)  Single 
Sided Associated Bidirectional LSPs  (A)" and wishes to control both 
forward and reverse  LSPs by adding "REVERSE_LSP" object, I would think 
that the ingress node needs to know about the signaling (path) errors 
(such as soft preemption or admission failure) on the reverse LSP.  Is 
there any text somewhere in an RFC/draft that describes how a mid-point 
node can send the signaling (path) error to the originating ingress node 
for the reverse LSP? Is there an assumption to use RSVP_NOTIFY message? 
Sorry if I had missed any previous discussion on this topic.
> 
> Thanks,
> Rakesh
> 
> 
> 
> 
>