I'm wondering how to calculate number of nodes in CIDR network?
for example if the CIDR network is 11.13.0.0/16 How many nodes can be accommodated in this CIDR network?
Any help would be appreciatet
Typically you'll have a broadcast address, so that's one address removed. You'll also typically have a router/default gateway, so that's often one more address removed. So that leaves 2^(32-16)-2==65534 IP addresses free for other use. If you want to subnet that further, you'll lose one more IP per subnet, since each subnet will have its own broadcast range.
In general terms thats 2^(32-bits_set_in_mask) addresses. As sarnold pointed out some of those can't be used for nodes.
Related
I know that each IP class has a default network mask (class A: 255.0.0.0, class B: 255.255.0.0 and class C: 255.255.255.0).
I have been reading the subnetting.net tutorial and they use the default (classful) network mask for subnetting (Question Type 2 Written Example), but on the other hand I read all the time that IP classes are obsolete.
What is exactly a default network mask?
Is it needed for subnetting?
Am I confusing concepts? (I suspect I am)
Please help, this is burning my head.
The IP address can never become obsolete a similar anology can be your home address becoming obsolete. The fact that IPv4 addresses are drying up Because there are that many devices in the globe now which is greater than the number of ip's available. That's why we are moving to IPv6...
A subnet mask is a number that defines a range of IP addresses available within a network. A single subnet mask limits the number of valid IPs for a specific network. Multiple subnet masks can organize a single network into smaller networks (called subnetworks or subnets).
For exp a subnet mask of 255.255.255.0 allows for close to 256 unique hosts within the network (since not all 256 IP addresses can be used).see Why do we need subnet mask?
I am trying to learn how to calculate IP addresses from CIDR block.
For example, 10.88.135.144/28 or
10.88.135.10010000/28
From what I understand, that means first 28 bits are associated with network address while the rest 4 bits are host addresses. That would result in following IP range:
10.88.135.10010000 - 10.88.135.10011111
The first IP should be 10.88.135.144 and last IP address should be 10.88.135.159
But according to cidr.xyz. The first IP should be 10.88.135.145 and the last one should be 10.88.135.158.
I really can't figure out why. Can anyone explain the reason for me? Thanks!
Generally, the first IP is the network identifier and cannot be assigned to any device.This is used by router or switch on the network.
The last one is the broadcasting IP and cannot be assigned to any device as this IP is used by router or switch on the network to broadcast information.
https://www.quora.com/In-IP-addresses-what-is-meant-by-network-ID-and-host-ID
https://supportforums.cisco.com/t5/wan-routing-and-switching/what-is-broadcast-address/td-p/2494445#messageBodySimpleDisplay_1
I have browsed a lot, but all articles seems to be focused on host-address range and not the range available for network addresses for a given CIDR block.
So let's say there are these 2 valid CIDR blocks:
10.0.0.0/16
172.31.0.0/16
Both provides the same host-address range. But does both provide the same network address range? I suppose no. But then what are those ranges? And which protocol rule mandates it?
Once a CIDR block is allocated to a network, the network has control over only the bits reserved for host addresses. And if the subnets are to be created within this network, it has to use the available bits for addressing network address.
When you create a subnet, you specify the CIDR block for the subnet, which is a subset of the parent network's CIDR block.
Hence the no of subnets/ networks which can be created within a network with either CIDR block 10.0.0.0/16 or 172.31.0.0/16 would be same.
Number of IP-addresses in practice when paired with subnet masks: Should IP-addresses paired with different subnet masks be seen as distinct?
I know an IP-address is represented as 4 octets, i.e. using 32-bits. The total is 2^32 different IP-addresses.
But these IP-addresses are paired with a subnet mask. Does this mean that 192.168.0.1/24 and 192.168.0.1/16 are two different IP-addresses in practice? If so, why not introduce some more "layers" (more masks) that extend the 32-bit addressing scheme even further?
How many IP-addresses are there?
Should IP-addresses paired with different subnet masks be seen as distinct?
No. A subnet mask is not a qualifier or namespace for IP addresses. Netmasks have no part in associating IP addresses with machines. Rather, they are associated with the physical and logical topology of the (IPv4) network, and they are needed for hosts to participate in the network appropriately. Using a different netmask does not change the meaning of IP addresses, so netmasks do not provide a mechanism for expanding the address space.
Does this mean that 192.168.0.1/24 and 192.168.0.1/16 are two different IP-addresses in practice?
No. In fact, those are not IP addresses at all -- they are (address, netmask) pairs, both with the same address part. On any given network, they refer to the same machine (if they refer to any machine at all). The IP address involved is in one of the non-routable ranges, however. These are usually used for internal networks, typically behind a router that performs network address translation (NAT) so that multiple machines can access the network without having globally-unique addresses. That has nothing to do with netmasks, however.
How many IP-addresses are there?
There are exactly 232 (a bit less than 5 billion) distinct IPv4 addresses. Not all of them are usable as host addresses. Use of private networks with NAT-ed access to the Internet expands the total number of machines that can be connected, but that does not change the number of distinct addresses, and it anyway is not related to netmasks.
Given the network address of 112.44.0.0 and the network mask of 255.255.0.0 .Would the two stations with addresses 112.44.22.19/16 and 112.44.23.2/16 be on the same network ?
Yes, of course.
All addresses 122.44.x.x will be in the same network.
Network mask 255.255.0.0 shows that first two numbers are showing number of network and other two numbers are showing number of edge.
Yes they are in the same subnet. Just go through the wiki page to understand how exactly the IP addresses are resolved. 255.255.0.0 actually expands to 11111111111111110000000000000000 now if you perform a bit wise and operation to any of the IPs 112.44.22.19 or 112.44.23.2 you will find that they give the same Network prefix ie. 112.44.0.0. What means these two machines are in the same subnet.