What does the term ‘fully-converged’ mean in networking? and again what does it mean "Prone to looping due to convergence".
Im reading about different protocols like R.I.P, OSPF, BGP, and I didn't really understand those terms.
Im looking around but I can't find any specific answers about it.
Any ideas?
When a network contains layer 2 and layer 3 devices, then this devices takes some time to 'understand' the topology of the network.
This is done when the layer 3 devices builds up a table ( routing table) based on the various routes, may be static, dynamic or directly connected routes. This table develops until the complete topology of the network is mapped out in the routing table. Then we can say the network is fully-converged.
Routing-management protocols like RIP, OSPF, and BGP are all about the distribution of information about network paths between and among network nodes. All such protocols tend to have a model where each node has its own view of what some or all of the network-path topology looks like. The nodes exchange information to drive all nodes to a common, "converged", view of the network. A "fully converged" network is one in which all the nodes fully understand the paths through it.
Related
I have a bidirectional ring network topology with 9 routers. What would you suggest to reduce the size (number of rows) in a routing table, and a number of hops?
I suggest using a dynamic routing protol such as OSPF or RIP / EIGRP .
using HSRP for switches : https://en.wikipedia.org/wiki/Hot_Standby_Router_Protocol
I think what confusing you is that if every two of the nodes build a connection, the network may become comlpex.
Firstly, since the topology is small, a controller may be a good choice for you. If you don't want it, then you can use some algorithm like dijkstra, OSPF, RIP, or something others like ants colony algorithm, genetic algorithm which can work well in large network.
How can defined topology in Castalia-3.2 for WBAN ?
How can import topology in omnet++ to casalia ?
where the topology defined in default WBAN scenario in Castalia?
with regard
thanks
Topology of a network is an abstraction that shows the structure of the communication links in the network. It's an abstraction because the notion of a link is an abstraction itself. There are no "real" links in a wireless network. The communication is happening in a broadcast medium and there are many parameters that dictate if a packet is received or not, such as the power of transmission, the path loss between transmitter and receiver, noise and interference, and also just luck. Still, the notion of a link could be useful in some circumstances, and some simulators are using it to define simulation scenarios. You might be used to simulators that you can draw nodes and then simply draw lines between them to define their links. This is not how Castalia models a network.
Castalia does not model links between the nodes, it models the channel and radios to get a more realistic communication behaviour.
Topology is often confused with deployment (I confuse them myself sometimes). Deployment is just the placement of nodes on the field. There are multiple ways to define deployment in Castalia, if you wish, but it is not needed in all scenarios (more on this later). People can confuse deployment with topology, because under very simplistic assumptions certain deployments lead to certain topologies. Castalia does not make these assumptions. Study the manual (especially chapter 4) to get a better understanding of Castalia's modeling.
After you have understood the modeling in Castalia, and you still want a specific/custom topology for some reason then you could play with some parameters to achieve your topology at least in a statistical sense. Assuming all nodes use the same radios and the same transmission power, then the path loss between nodes becomes a defining factor of the "quality" of the link between the nodes. In Castalia, you can define the path losses for each and every pair of nodes, using a pathloss map file.
SN.wirelessChannel.pathLossMapFile = "../Parameters/WirelessChannel/BANmodels/pathLossMap.txt"
This tells Castalia to use the specific path losses found in the file instead of computing path losses based on a wireless channel model. The deployment does not matter in this case. At least it does not matter for communication purposes (it might matter for other aspects of the simulation, for example if we are sampling a physical process that depends on location).
In our own simulations with BAN, we have defined a pathloss map based on experimental data, because other available models are not very accurate for BAN. For example the, lognormal shadowing model, which is Castalia's default, is not a good fit for BAN simulations. We did not want to enforce a specific topology, we just wanted a realistic channel model, and defining a pathloss map based on experimental data was the best way.
I have the impression though that when you say topology, you are not only referring to which nodes could communicate with which nodes, but which nodes do communicate with which nodes. This is also a matter of the layers above the radio (MAC and routing). For example it's the MAC and Routing that allow for relay nodes or not.
Note that in Castalia's current implementations of 802.15.6MAC and 802.15.4MAC, relay nodes are not allowed. So you can not create a mesh topology with these default implementations. Only a star topology is supported. If you want something more you'll have to implemented yourself.
I need to create two wireless networks and one ethernet network with ns-3 but all my ideas doesn't seem to work as I can't have collison. I was trying to create something connected like:
(wifi) ----point to point--- (ethernet)--- point to point--- (wifi)
can't post image, here is a link
It didn't work, it seems because I need something called point-to-multipoint communication and I don't know how to do that on ns-3 (I didn't even found about it on ns-3) and I hardly find reference about this matter. Tried to just create three nodes and assign two with wireless node and one with ethernet while trying that.
Also tried to create two pair of nodes with a point-to-point communcation between each but I realized I was changing the problem.
What you need is add two network interfaces for each node, one for point-to-point and another for Wi-Fi.
Interfaces
See the code sample in the ns3 source code for an example:
src/examples/tutorial/third.cc
I know I should be asking this question on Network Engineering section of Stack Exchange but it feels like it's a desert there.
I'm trying to build an application that requires the distance between 2 hosts (represented by IP).
I used many methods: one of them is to get the distance at the internet layer of the TCP/IP model; i.e: the hop count between the 2 networks or better to get the bandwidths of the path but I think this information can't be measured because it's a real time info.
I figured out that there should be a graph representing the internet graph which its nodes are the routers (or autonumus systems or sub-networks (I really don't know exactly what type of nodes it should be) and the edges of the graph should be the cables between the nodes which have the bandwidth to be the wieght of the edge.
My Question:
Where can I find this information; whether the full graph or parts of it or something like an API to get 2 IPs and return the shortest path between the 2 IPs.
There is a tool named "Tracert"
You could have it try.
It will represent the routines of peer to peer in internet.
Hope that it make
Will I have loop problems with this topology because S2 and S3 are both connected to S1 and s4 ?
Please check out this wikipage. It summarizes switching loops and the problem associated with them.
Obviously, to solve this issue you could just remove a link/ switch (S1 or S4) which forms the physical loop in the first place; although the result is you lose redundancy.
The ideal solution is to configure spanning tree protocol (STP) on these switches to dynamically block some interface(s) so that one active path exists between the two endpoints (PCs on S2 to PCs on S3) at any time. Note, with spanning tree configured you do not get load-balancing over the redundant link/ switch.
What you need is Spanning tree protocol, turn on this function in your switch.
It's a loop-free topology for any bridged Ethernet local area network.
This protocol will disables links that are not part of the spanning tree, leaving a single active path between any two network nodes.
We often use RSTP(802.1w) instead of STP(IEEE 802.1D), for the previous provides faster spanning tree convergence after a topology change.
If you use VLAN in your environment, you may choose MSTP(Multiple Spanning Tree Protocol).
In simple ring topology, u can use ring protocols too!
like G8032 (ERPS)
G8032 wiki
http://en.wikipedia.org/wiki/Ethernet_Ring_Protection_Switching
G8032 archive
http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/cether/configuration/xe-3s/ce-xe-3s-book/ce-g8032-ering-pro.html