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Networking fundamentals: IP addressing

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Internet Protocol (IP) addresses are assigned to hosts so they can communicate with devices on different networks. IP addresses assigned to clients on Cisco Meraki networks are viewable on the Monitor > Clients page for MR Access Points, MX Security Appliances and MS Switches or from the command prompt using ipconfig on Windows devices. 

Calculating IP addresses

 

IPv4 addresses consist of a network portion and a host portion. The address is split based on the network's subnet address. This concept is explained using the following example IP address configuration.

IP Address: 192.168.0.1

Subnet Mask: 255.255.255.0

Default Gateway: 192.168.0.254

In this example, the host client that is configured with these settings can be reached at address 192.168.0.1. When the client does not know how to reach another client (i.e. the other client is not in the same subnet), the client will send traffic to the default gateway, which is 192.168.0.254. A subnet mask will tell the client which subnet it is in and is also used by the network administrator to configure networks with a specific amount of addresses.

In this case, the subnet mask of 255.255.255.0 (/24 in CIDR), tells us that the network portion of the address is the first 3 octets (192.168.0). Each host on this network will always have a prefix of 192.168.0. The only portion that will change is the last octet which will be 1 - 254, with .255 being the broadcast address for all clients in the network.

As the subnet address changes, there will either be more hosts and less networks, or less hosts and more networks. For example, the private address range of 10.0.0.0/8 utilizes a smaller subnet mask (255.0.0.0). This allows the network administrator to have up to 16,777,214 hosts in one network. The previous example utilized the 255.255.255.0 subnet mask which only allowed the administrator to have 254 clients in the subnet.

Consult the Knowledge Base to learn more about subnetting

IP address assignment

 

IP addresses can be statically or dynamically assigned. 

Dynamic addressing utilizes DHCP (Dynamic Host Configuration Protocol). This protocol allows clients to turn on their device and obtain an IP address on the network automatically and is ideal for networks with large numbers of end user PCs and mobile devices. MX Security Appliances, Z1 Teleworker Gateways, and MR Access Points can be configured to provide DHCP services to network clients. 

Static IP addressing is used when a device needs the same address each time it connects to the network. This is specifically useful when file servers or network devices need the same IP address for management and access purposes. Consult the product manuals to learn how to statically assign IP addresses to MR Access Points, MX Security Appliances, and MS Switches

IPv6

At this time, IANA (Internet Assigned Numbers Authority) is developing IPv6 which is slowly being implemented on network devices. There are several differences between IPv4 and IPv6.

IPv4 addresses are 32 bits and expressed in dotted decimal notation (for example, 192.168.100.1) whereas IPv6 addresses consists of 128 bits expressed in hexidecimal notation (for example, 2001:0db8:85a3:0042:1000:8a2e:0370:7334). Additionally, clients can have multiple IPv6 addresses (an IP address for the local network, and a routable IP address). IPv6 also has IPSec built in natively which allows clients to establish secure connections between each other in both the WAN and the LAN.

More information on IPv6 addressing and features please refer to this article.

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Last modified
10:25, 20 Jan 2017

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ID: 1809

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