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Hi all, I was reading the draft-ietf-ccamp-lmp-10 document and in the paragraph 5 I found a part which is not completely clear to me.
Suppose I want to verify the link connectivity between two transparent switches, A and B, where A is the node that initiates the procedure. - One part of the text asserts that “to ensure proper verification of data link connectivity, it is required that until the data links are allocated for user traffic, they must be opaque (i.e., lose their transparency).”: from here I understand that node B has to terminate all the ports that are not currently transmitting data (i.e. all the ports that have not been already verified). - On another part I found: “There is no requirement that all data links be terminated simultaneously, but at a minimum, the data links MUST be able to be terminated one at a time”: here it looks like B does not have to terminate all the not-yet-verified ports at the same time. However in this case B may not receive a message sent from node A over a certain link even if that link is actually connecting node A to B (in fact the port of B relative to that link may be not terminated in that occasion).
Which one is the correct interpretation? Should node B have all the not-yet-verified ports terminated at the same time when node A starts the link verification?
This is the text of paragraph 5 I referred to: “A unique characteristic of transparent devices is that the data is not modified or examined in normal operation. This characteristic poses a challenge for validating the connectivity of the data links and establish the label mappings. Therefore, to ensure proper verification of data link connectivity, it is required that until the data links are allocated for user traffic, they must be opaque (i.e., lose their transparency). To support various degrees of opaqueness (e.g., examining overhead bytes, terminating the IP payload, etc.), and hence different mechanisms to transport the Test messages, a Verify Transport Mechanism field is included in the BeginVerify and BeginVerifyAck messages.
There is no requirement that all data links be terminated simultaneously, but at a minimum, the data links MUST be able to be terminated one at a time. Furthermore, for the link verification procedure it is assumed that the nodal architecture is designed so that messages can be sent and received over any data link. Note that this requirement is trivial for opaque devices since each data link is electrically terminated and processed before being forwarded to the next opaque device, but that in transparent devices this is an additional requirement.”
Best Regards, Marco Ruffini.
CTVR, Trinity College, Dublin 2, Ireland. Phone: +353-1-608 8442
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