I'm wondering if two nodes on same network/sub-network can have same ip addresses?
Now i know that by definiton ip addresses are unique and that's how nodes are identified on network layer but i got this question in a quiz paper so is that possible anyhow?
For eg if i am on a private network and then if try to set same ip addresses for two different nodes it gives IP adress conflict but answer was YES in that quiz for this question.So if anybody can suggest any possible reason,it would be deeply appreciated.
Please let me know if it's not possible.
they can, but they must not.
If the client know or cache the mac address , it can comunicate with one node
but the next arp request can change the mac address and continue with the other.
It can send udp message to the wrong node , but broke tcp connections.
Related
The setup is this:
We have a group of computers that have public ip addresses assigned to them so that they can access the internet. these computers are connected together forming a pure (trackerless) peer-to-peer network.
My understanding of the public ip address system is that those addresses are not unique to each router meaning that a router can have an ip address today and have a totally different one tomorrow or in the next hour or maybe a week from now.
The problem is what happens if nodes in the network have had their public ip address changed to a new one while they were not connected to the network. how are these nodes supposed to rejoin the network?? should each node maintain a list of all the public ip addresses of the all the nodes in the network and try to open a connection to each one of theme?? if yes what if the network has a million nodes, what about timeouts if the ip address is still the same but the connection failed for some reason??
Another problem arises when all the nodes have had their ip addresses changed simultaneously. how are they supposed to reassemble the network without any working ip addresses??
it would be appreciated if you could recommend books, articles or videos that explain how peer-to-peer apps like trackerless file sharing apps function on a more technical level (Nat traversal, and initial bootstrapping to the distributed hash table).
The fix is either to have a registrar at a well known address (i.e. not a peer) or seed each node with address of a number of peers (say, 10 or 100). I seem to recall a paper on this and it's was a relatively small number to find a live node in practice. When a peer boots up try to each peer till you find the network. Once you find one, you can get a current seed list and figure out which peers you want to connect to.
The other question that also comes up (along with NAT) is how do you connect to node behind a firewall. The term you want to look up is Hole punching.
If your nodes are on a lan you have broadcast options. This is how DHCP works for instance. You might want to check out Zero-configuration networking. Multicast might be an option on wan.
I am sorry if its basics, but I did not find the appealing answer for it over the Internet.
Why only MAC is used to transfer the packet to a device ? MAC address is only obtained by ARP for a specific IP address. So, why not just let the routers maintain IP addresses of the neighbouring routers and route packets using IP addresses of routers instead of MAC addresses ?
Why not redesign the architecture, to only use IP address for routing as well as moving the packet in the data link layer too ?
Why do we need MAC addresses?" Why can't network devices such as the routers just send the packet to the next router using the router's IP address?
Note : I know that MAC address is used to identify the system in a network. But you see the source never knew the MAC address of receiver. All it knew was its IP address and MAC address of next hop.
I'm reading Data Comm and Networking by Forouzan ( Ed 5) and it says that even routers have an IP address. So why use the mac address at all. The router can store the IP address of the source and route it to the next router .
EDIT : The question that I was getting as suggestion to this one does not answer my query. There are multiple counter points and proof that I have presented here which could have been done which is not answered by the one which is suggested. So please read my question before making any assumptions.
What do you think makes more sense: Having one protocol like Ethernet handle all the layer 2 details so that its layer 3 payload doesn't have to care, or force IP, ARP, WoL, IPX, MPLS, SLPP, and dozens more implement it on their own? The whole purpose of OSI layers is that upper layers need not know all the lower layer's details and lower layers need need not support the upper layer's features.
MAC addresses are used for the layer 2 protocol which encapsulates a layer 3 protocol. If all the necessary features were embedded into IP, then you'd be leaving other protocols to re-implement layer 2 routing on their own. This would be wildly inefficient.
[I did my research]
I read the IPv4 and Subnetting chapters in the CCNA prep material. Watched several youtube videos and read through several forums. However, I still have a small issue because different sources use certain terms interchangeably however I want to be certain and confirm my understanding to avoid confusion.
[The Question]
Q1
Is the network address the same as the node address the same as the network id ?
Q2
Is the host address the same as the host id?
for instance:
in this ip 184.19.39.34 is 184.19 the network address == the node address == the network id?
is 39.34 the host address == the host id?
Thanks alot guys !
Q1: Basically, yes. You should note though that there are different kinds of network addresses such as IP addresses, subnet addresses/prefixes, or MAC addresses. The exact meaning of each term depends on context.
Q2: If the IP address/mask is 184.19.39.34/16 then 184.19.0.0/16 is the subnet address. 39.34 is the host part of the IP address while 184.19 is the network part. The IP address is split into these parts as indicated by the CIDR value or the network mask (255.255.0.0 for /16).
Note that this split is only relevant for routing and on the last hop, so you don't need to know the mask value of a far IP address.
Answer Q1 :
yes, But on as desired of the Mac or virtual IP or a value for the IP
Answer Q2 :
Gluttony complement each other
You can find a detailed answer here :
[https://www.geeksforgeeks.org/ip-addressing-introduction-and-classful-addressing/][1]
I am person trying to learn networking. I understand that this may not be the best first step to take, but I am eager to try and understand how this takes place because it has been tearing up my mind for quite a while now.
My question is, how does a network recognize a device and automatically connect it to the network?(This is assuming, of course, that you have connected to the network previously and are connecting wirelessly.)
Does it store it on the routers side and then look for specific MAC Addresses and then connect it? Or is it stored somewhere on an encrypted file on your computer? Or is it none of these? Please forgive me if I am way off, I am only giving guesses from what I have so-far learned from networking.
'Connect it to the network' doesn't really mean anything, other than just plugging it in, or turning it on in the case of Wifi. What really happens is that the device broadcasts a DHCP request for an IP address, or else It already has an IP address in that subnet. From that point on it is discoverable by ARP, so other hosts in the subnet can send to it.
Hello Networking Gurus,
I have a question about IP duplication and how this impact the associated switches (layer 2). Sorry, I don't have any resources available to test this. It would be great if someone can shed some lights of their experience on this.
If I have two servers (Linux), say A & B, serving exactly same contents and for some reason they both are assigned same IP address. To be more specific, if A already has an address IP.100 and B has another address IP.200. Now at this point everything seems working and the switch has proper MAC addresses stored. If, later, B also gets the address IP.100, how would this affect the switch's ARP cache? When B gets the new address I assume it broadcasts ARP? to inform the associated switch.
So the question is, Does the switch stores both machines' entries? or overwrites the existing with new? Is there any standard behaviour or proprietary switches reacts differently?
If a client, with no ARP cache, tries to connect to IP.100, which machine would it be forwarded to? A or B or none? If A OR B, can I say from client point-of-view, that there's no outage? (Assume this is a static website, with no login sessions etc)
Feel free to point any relevant documentation.
Thank you in advance.
In theory, you shouldn’t have two hosts talking on the same IP, unless they are participating in routing. Eg any-cast. As things will break.
Each host will have its own MAC address. If the switch is only doing layer two forwarding, then the switch only keeps track of MAC addresses. It is the end hosts or routers that track ARP entries.
If you move IP 100 to B, then the hosts will update their own ARP table.
But if A and B have 100 at the same time, this will cause issues.
Switch will not see any IP's and do not have arp cache for forwarding packets , it will had only mac address table map macs to ports and macs in your case will be unique
I actually think this is how multicast works.
Hosts obtain a multicast address and all of the devices share that same multicast address.
A switch will gather collections of Mac addresses to that same multicast in it's mac table.
I could be wrong though....Still learning.