RE: [IP-Optical] LMP: Link verification procedure suggestions.

[Jonathan Lang <jplang@calient.net>]

Murugan,
Please see inline.  [Note, IPO list clipped to avoid cross-posting.]

Thanks,
Jonathan

-----Original Message-----
From: Murugan .A [mailto:mamirtha@npd.hcltech.com]
Sent: Wednesday, December 05, 2001 5:58 AM
To: ccamp@ops.ietf.org; ip-optical@lists.bell-labs.com
Cc: MURUGAN AMIRTHALINGAM; rashanmu@npd.hcltech.com
Subject: [IP-Optical] LMP: Link verification procedure suggestions.

>Hi,
> Giving below the test procedures followed by the IETF draft and my
suggestions for them. 
> Both nodes exchange their testing capabilites(sequential/simultaneous)
through BeginVerify
> and BeginVerifyAck.
There is no notion of exchanging sequential/simultaneous testing
capabilities. The protocol is designed to support both capabilities without
negotiation.

>
> The local node also sends if it has the interface mappings(not know
intially) in BeginVerify. 
> When the mappings are known, if both nodes support's simultaneous testing,
simultaneous
> testing is done.
>
>If only one node support's simultaneous testing, then both nodes do
sequential testing with
>the know ordering.
>
>
>1) sender testing capability:sequential, receiver testing
capability:simultaneous, mappings
> are not known.
> IETF:
> Verification procedure is started with number of links to be tested equal
to all links in
> the TE/data set. Sender sends test message in one of the links(as per its
internal ordering). 
> Receiver waits in all the links. 
>
> Receiver may receive test message in just one of the links, for all other
links it will not
> receive test message within VerifyDeadInterval. At the end of
VerifyDeadInterval the remtoe
> node would have send TestStatusSuccess or TestStatusFailure for all the
links. 
>
> The sender sends TestStatusAck for all the links. The verification
procedure is completed. 
>
> At the end of this verification procedure mapping is found out for only
one link(provided 
> beginVeryAck is received).
> The above procedure has to be repeated again and again unitl mapping is
found for all links.
No. The VerifyDeadInterval is set for *each* Test message. This is
configured at the receiving node and indicates that if a Test message is not
seen within the VerifyDeadInterval, the Test procedure has failed for that
data link. In your above example, once the receiver sees a Test message, it
sends a TestStatusSuccess message to the sender.  If instead, the
VerifyDeadInterval is reached without receiving a Test message, A
TestStatusFailure message is sent.  At this point, the sender can transmit a
new Test message down the next data link. 

>
>My suggestion:
> The sender informs the receiving side that it is capable of testing
sequentially only. It also 
> informs the remote node that it doesnot have interface mappings. Receiver
sends BeginVerifyAck,
> with VerifyDeadInterval set to "locally configured VerifyDeadInterval for
single data link"
> * "no of links to be tested".
> The local node will send test messages in a interface sequentially for
every verify interval
> and the number of retries for an interface will be stopped based on local
configuration
>( retransmission count or timer).
>
> Remote node is waiting for "VerifyDeadInterval for single data link" * "no
of links to be
> tested" for all interfaces. This time is enough to receive test message
send in any order
> over the links.
>
> 2) sender testing capability:sequential, receiver testing
capability:sequential, mappings are
> not known.
> 
>IETF:
> Not clear how testing is done in this case. Since sender follows its own
ordering for sending
> test messages over different interfaces, where as the receiver follows its
own ordering
> waiting to receive test messages over interfaces. There is no correllation
of the ordering
> between the two.
The LMP procedure is the same as I described above.

>
>My suggestion:
> The sender informs the receiving side that it is capable of testing
sequentially only. It also
> informs the remote node that it doesnot have interface mappings.
>
> The receiver also informs the sender that it is capable of doing testing
sequentially and sets
> VerifyDeadInterval to "locally configured VerifyDeadInterval for single
data link" * "no of
> links to be tested".
> 
> Remote node is waiting for "VerifyDeadInterval for single data link" * "no
of links to be
> tested" for one interface. After the end of this period it waits in the
next interface.
> 
> The local node will send test messages in a interface sequentially for
every verify interval
> and the number of retries for an interface will be stopped based on local
configuration
> ( retransmission count or timer). At the end of this period it may know
mapping for just
> one link. Since the local node know that the remote node is only capable
of sequential testing
> the above procedure has to be repated.
>
>Thanks,
>Murugan
>Ramesh