http://i-gorod.org/itblog/2007/07/14/isoosi-layers-in-manets/ Personal web site of Ilya Gorodnyanskiy Wed, 14 Mar 2012 13:33:32 +0000 hourly 1 http://wordpress.org/?v=3.0.2 http://i-gorod.org/itblog/2007/07/14/isoosi-layers-in-manets/comment-page-1/#comment-59 Ilya G. Sun, 05 Aug 2007 13:25:50 +0000 http://i-gorod.org/itblog/2007/07/14/isoosi-layers-in-manets/#comment-59 Sorry for my delayed answer. Notwithstanding it sounds weird, it makes sense. The task of the network layer is to propagate the information from one node to the other one. So, if the application layer says: hey, please deliver the information to a node A, the network layer obeys and finds out an optimal way depending on the current network topology. But, a relay network is a network above the network layer. So there exist nodes A, B, C, D etc. at the application layer, let's call them virtual nodes and there exist nodes at the network layer A', B', C', D' etc. let's call them physical nodes. So now, let's imagine that A sends something to C via B: A -> B -> C. When application layer at A sends an information unit to B, the network layer does not know, that this unit will go further to C, it's only responsible for delivering the information unit from A to B! The decision to forward the information to C is made at the Application Layer! Sorry for my delayed answer. Notwithstanding it sounds weird, it makes sense. The task of the network layer is to propagate the information from one node to the other one. So, if the application layer says: hey, please deliver the information to a node A, the network layer obeys and finds out an optimal way depending on the current network topology. But, a relay network is a network above the network layer. So there exist nodes A, B, C, D etc. at the application layer, let’s call them virtual nodes and there exist nodes at the network layer A’, B’, C’, D’ etc. let’s call them physical nodes. So now, let’s imagine that A sends something to C via B: A -> B -> C. When application layer at A sends an information unit to B, the network layer does not know, that this unit will go further to C, it’s only responsible for delivering the information unit from A to B! The decision to forward the information to C is made at the Application Layer!

]]> http://i-gorod.org/itblog/2007/07/14/isoosi-layers-in-manets/comment-page-1/#comment-51 Ilya Wed, 18 Jul 2007 13:05:45 +0000 http://i-gorod.org/itblog/2007/07/14/isoosi-layers-in-manets/#comment-51 Imo, this sounds a bit strange. I mean, it looks logicaly to make decisions about network topology on the network level, but not in the application level. May be there is not enough information about topology on the Network level (and that is why Application level is involved into routing)? Imo, this sounds a bit strange. I mean, it looks logicaly to make decisions about network topology on the network level, but not in the application level. May be there is not enough information about topology on the Network level (and that is why Application level is involved into routing)?

]]> http://i-gorod.org/itblog/2007/07/14/isoosi-layers-in-manets/comment-page-1/#comment-50 Ilya G. Tue, 17 Jul 2007 13:00:04 +0000 http://i-gorod.org/itblog/2007/07/14/isoosi-layers-in-manets/#comment-50 In general there is no difference. For the application layer there are also only two connection states: connected and disconnected. But in some cases the application layer has to take care about the underlying layers. For example think of relay networks and the classical p2p applications like BitTorrent etc. If a node A is connected with the node B at the application layer, it's only one hop. But at the network layer there may be more hops between. So the shortest way between two nodes at the application layer is not always the shortest was at the network layer. In usual networks where the bandwidth plays no significant role that's not a problem. But in ad hoc networks it may be critical. So designing relay networks for ad hoc networks one should take into consideration the network topology at the application layer too. In general there is no difference. For the application layer there are also only two connection states: connected and disconnected. But in some cases the application layer has to take care about the underlying layers. For example think of relay networks and the classical p2p applications like BitTorrent etc. If a node A is connected with the node B at the application layer, it’s only one hop. But at the network layer there may be more hops between. So the shortest way between two nodes at the application layer is not always the shortest was at the network layer. In usual networks where the bandwidth plays no significant role that’s not a problem. But in ad hoc networks it may be critical. So designing relay networks for ad hoc networks one should take into consideration the network topology at the application layer too.

]]> http://i-gorod.org/itblog/2007/07/14/isoosi-layers-in-manets/comment-page-1/#comment-49 Ilya Mon, 16 Jul 2007 08:04:46 +0000 http://i-gorod.org/itblog/2007/07/14/isoosi-layers-in-manets/#comment-49 By the way, what is the difference for Application layer to use usual network or ad hoc network? Does it need take some special care about connection lost and something like this? By the way, what is the difference for Application layer to use usual network or ad hoc network? Does it need take some special care about connection lost and something like this?

]]>