I've tried looking at a lot of resources but I cannot figure out how I can express.
5.248.*.*
in subnet form. I know how I would do 5.248.1.0/24, but what about two subnets?
You are not talking about two subnets, but rather a B-class subnet containing 16-bits, i.e.
5.248.0.0/16
Related
I've been told that it is bad practice to have two interfaces on the same device on the same subnet. i.e. two Ethernet ports on a switch should be on different subnets. Could somebody explain why this is the case? (preferably simply as possible as I'm new to networking)
Because routing in your OS normally sets one of Ethernet card as out gate to specified subnet and all traffic to this subnet will have only 1 output. Second route to same subnet will have bigger Metrik value and will use to send some data if first interface is down. Even if somebody will send request to second interface answer can have first Ip as sender.
If you try to increase throughput to subnet you must use aggregation of Ethernet link. you`ll have 2 physically link and 1 IP.
subnet is the logical division of the IP network based on the subnet-mask/netmask. So unless you plan to have two different separate networks, you need not to have two different subnets. This link explains most of the possible cases to explain what it means by subnetworks on a switch.
Whether two interfaces on the same subnet is good or bad depends entirely of what you're trying to accomplish.
If you need link redundancy or a simple way of load sharing (L2 or L3) it may the right way to go.
If you need network/uplink redundancy or a more complex way of load sharing (L3 only) you connect to two different networks (multi-homing). This is also the setup for a router connecting the two networks.
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.
Is there anyway to isolate devices that belong to the same subnet ?
In other words, isolate some devices in the subnet from the broadcast domains.
I was thinking of using vlans but I guess it is not functional.
I'm using SF200 cisco switch
my english is not very well
but i think vlan is a good way to solve you problem.
you can bulit two vlan in switch. and put the devices in different vlans.
communication with different vlans you can use some devices worked in 3 layer.
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.
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.