TWiki > DNA > LinkHint > LinkHintIssue007	TWiki webs: Main | TWiki | Know | Sandbox
	DNA . { History of Changes | DNA Documents | Search | Go }

Back to DNA Link-Hints Document Issue Tracker

updated 9 Mar 2005

" Two basic link-layer events are considered potentially useful to DNA process: link up and link down. Both of these events are deterministic, and their notifications are provided to IP-layer after the events successfully conclude."

[BA] The "Up" and "Down" link states are only determinstic on wired networks. On wireless networks, frame loss can be intermediate between the "up" and "down" states, so that link state indications may not be reliable.

Node's establishment of a link-layer connection with an attachment point that signifies the availability of IP service (i.e., being able to send and receive IP packets) between the two is considered a link up event.

[BA] I think we need to distinguish changes in link state due to frame loss from "Link Establishment" and "Link Termination" events. As used in this document I am not clear whether "Link Up" refers to the state of the link or whether we are really talking about a "Link Establishment" event. For example, a link can be established, and then experience high frame loss (e.g. mobile node wanders out of range). Does this then constitute a "Link Down" event, followed by a "Link Up" event when frame loss becomes low again? For the purposes of DNA, don't we only need to care about "Link Establishment" events (not even "Link Termination")?

--

-- Main.GregDaley - 09 Mar 2005

Back to DNA Issue Tracker Base Page