What is the maximum number of ipv6 addresses that can be assigned to one ipv6 interface?
|
IPv6 is the next generation Internet Protocol (IP) address standard intended to supplement and eventually replace IPv4, the protocol many Internet services still use today. Every computer, mobile phone, home automation component, IoT sensor and any other device connected to the Internet needs a numerical IP address to communicate between other devices. The original IP address scheme, called IPv4, is running out of addresses due to its widespread usage from the proliferation of
so many connected devices. IPv4 stands for Internet Protocol version 4. It is the underlying technology that makes it possible for us to connect our devices to the web. Whenever a device accesses the Internet, it is assigned a unique, numerical IP address such as 99.48.227.227. To send data from one computer to another through the web, a data packet must be transferred across the network containing the IP addresses of both devices. IPv6 (Internet Protocol version 6) is the sixth revision to the Internet Protocol and the successor to IPv4. It functions similarly to IPv4 in that it provides the unique IP addresses necessary for Internet-enabled devices to communicate. However, it does have one significant difference: it utilizes a 128-bit IP address. Key benefits to IPv6 include: IPv4 uses a 32-bit address for its Internet addresses. That means it can provide support for 2^32 IP addresses in total â around 4.29 billion. That may seem like a
lot, but all 4.29 billion IP addresses have now been assigned, leading to the address shortage issues we face today. IPv6 utilizes 128-bit Internet addresses. Therefore, it can support 2^128 Internet addresses—340,282,366,920,938,463,463,374,607,431,768,211,456 of them to be exact. The number of IPv6 addresses is 1028 times larger than the number of IPv4 addresses. So there are more than enough IPv6 addresses to allow for Internet devices to expand for a very long time. The text form
of the IPv6 address is xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx, where each x is a hexadecimal digit, representing 4 bits. Leading zeros can be omitted. The double colon (::) can be used once in the text form of an address, to designate any number of 0 bits. With Dual-IP stacks, your computers, routers, switches, and other devices run both protocols, but IPv6 is the preferred protocol. A typical procedure for businesses is to start by enabling both TCP/IP protocol stacks on the wide area
network (WAN) core routers, then perimeter routers and firewalls, followed by data-center routers and finally the desktop access routers. With IPv6 becoming more prevalent in cloud provider and consumer access networks, you may already be on the path to IPv6 deployment with your network and applications. If you are looking to understand IPv6 in your environment there are three things you should be monitoring: ThousandEyes has support for IPv6 so that organizations can utilize IPv6 across all of their test types (web, network, voice, routing) and agent types (cloud, enterprise, endpoint). ThousandEyes Cloud Agent support for IPv6 is provided on six continents allowing global coverage for organizations. ThousandEyes also supports the use of dual-stack IPv4 and IPv6 Enterprise Agents. Enterprise Agents can have both addresses
assigned and executes tests based on a user-defined preference for only IPv4, only IPv6 or a preference for IPv6. IPv6 Address FormatsAn IPv6 address is 128 bits long and is written as eight groups of four hexadecimal digits (base 16 digits represented by the numbers 0-9 and the letters A-F). Each group is separated by a colon (:). For example, FC00:0000:130F:0000:0000:09C0:876A:130B is a complete and valid IPv6 address. For convenience, IPv6 addresses can be written in a compressed format. Taking the IPv6 address FC00:0000:130F:0000:0000:09C0:876A:130B as an example:
An IPv6 address can contain only one double colon (::). Otherwise, a computer cannot determine the number of zeros in a group when restoring the compressed address to the original 128-bit address. IPv6 Address StructureIPv6 addresses have two parts:
You can manually configure the interface ID, generate it through system software, or generate it in IEEE 64-bit Extended Unique Identifier (EUI-64) format. Generating an interface ID in EUI-64 format is the most common practice. The 64-bit interface ID in an IPv6 address identifies a unique interface on a link. This address is derived from the link-layer address (such as a MAC address) of the interface. The 64-bit IPv6 interface ID is translated from a 48-bit MAC address by inserting a hexadecimal number into the MAC address, and then setting the U/L bit (the leftmost seventh bit) to 1. If the interface has been configured with a MAC address, the EUI-64 address is generated based on the MAC address of the interface, with FFFE added in the middle. If the interface has not been configured with a MAC address, the EUI-64 address is generated based on the following rules:
Taking the insertion of a hexadecimal number FFFE (1111 1111 1111 1110) into the middle of a MAC address as an example, see Figure 7-1 for the detailed conversion procedure. For example, if the MAC address is 000E-0C82-C4D4, the interface ID is 020E:0CFF:FE82:C4D4 after the conversion. Converting MAC addresses into IPv6 interface IDs reduces the configuration workload. When using stateless address autoconfiguration, you only need an IPv6 network prefix to obtain an IPv6 address. One defect of this method, however, is that an IPv6 address is easily calculable based on a MAC address, and could therefore be used for malicious attacks. IPv6 Address TypesIPv6 addresses can be classified as unicast, multicast, or a new class called anycast. Unlike IPv4, there is no broadcast IPv6 address. Instead, a multicast address can be used as a broadcast address. IPv6 Unicast Address An IPv6 unicast address identifies an interface. Since each interface belongs to a node, the IPv6 unicast address of any interface can identify the relevant node. Packets sent to an IPv6 unicast address are delivered to the interface identified by that address. A global unicast address cannot be the same as its network prefix because an IPv6 address which is the same as its network prefix is a subnet-router anycast address reserved for a device. However, this rule does not apply to an IPv6 address with a 127-bit network prefix. IPv6 defines multiple types of unicast addresses, including the unspecified address, loopback address, global unicast address, link-local address, and unique local address.
IPv6 Multicast Address Like IPv4 multicast addresses, IPv6 multicast addresses identify groups of interfaces, which usually belong to different nodes. A node may belong to any number of multicast groups. Packets sent to an IPv6 multicast address are delivered to all the interfaces identified by the multicast address. For example, the multicast address FF02::1 indicates all nodes within the link-local scope, and FF02::2 indicates all routers within the link-local scope. An IPv6 multicast address is composed of a prefix, a flag, a scope, and a group ID (global ID).
Figure 7-5 shows the IPv6 multicast address format. Figure 7-5 IPv6 multicast address format
IPv6 Anycast Address An anycast address identifies a group of network interfaces, which usually belong to different nodes. Packets sent to an anycast address are delivered to the nearest interface that is identified by the anycast address, depending on the routing protocols. Application scenario: When a mobile host communicates with the mobile agent on the home subnet, it uses the anycast address of the subnet device. Addresses specifications: Anycast addresses do not have independent address space. They can use the format of any unicast address. Syntax is required to differentiate an anycast address from a unicast address. As IPv6 defines, an IPv6 address with the interface identifier of all 0s is a subnet-router anycast address. As shown in Figure 7-6, the subnet prefix is an IPv6 unicast address prefix which is specified during configuration of an IPv6 unicast address. Figure 7-6 Format of a subnet-router anycast address An anycast address is not necessarily a subnet-router anycast address and can also be a global unicast address. How many IPv6 addresses are configured on the interface?Note that there are three IPv6 addresses configured on the interface, all of which were automatically generated: the link-local address and two globally scoped addresses.
How many devices can be on IPv6?IPv6 uses 128-bit addresses as opposed to the 32-bit addresses used by IPv4, allowing for a substantially larger number of possible addresses. With each bit corresponding to a '0' or '1', this theoretically allows 2^128 combinations or 340 trillion, trillion, trillion addresses.
Can multiple IPv6 addresses be configured on a single interface?IPv6 allows, and often requires, multiple addresses on the same interface. The is more difficult in IPv4, although not always impossible. What it means is that a host configured with multiple addresses on a single interface will receive traffic destined for any of those addresses.
Can an interface have multiple IPv6 addresses?It's completely normal to have multiple IPv6 addresses on one device. A device generates new 64 bits every once in a while and uses that in the IPv6 address. Because new addresses are generated regularly the addresses are marked as temporary interfaces.
|
