Local networks with large numbers of hosts are sometimes divided into subnets. If you choose to divide your network into subnets, you need to assign a subnet number for the subnet. You can maximize the efficiency of the IPv4 address space by using some of the bits from the host number part of the IPv4 address as a network identifier. When used as a network identifier, the specified part of the address becomes the subnet number. You create a subnet number by using a netmask, which is a bitmask that selects the network and subnet parts of an IPv4 address.
Host Part This is the part of the IPv4 address that you assign to each host. Subnet Number Optional Local networks with large numbers of hosts are sometimes divided into subnets. Link-local addresses cannot be used outside the link.
Site-local unicast addresses—Used only within a site or intranet. A site consists of multiple network links. Site-local addresses identify nodes inside the intranet and cannot be used outside the site.
Multicast addresses support 16 different types of address scope, including node, link, site, organization, and global scope. A 4-bit field in the prefix identifies the address scope. Unicast addresses identify a single interface. Each unicast address consists of n bits for the prefix, and — n bits for the interface ID.
Multicast addresses identify a set of interfaces. Each multicast address consists of the first 8 bits of all 1s, a 4-bit flags field, a 4-bit scope field, and a bit group ID:.
The first octet of 1s identifies the address as a multicast address. The flags field identifies whether the multicast address is a well-known address or a transient multicast address. The scope field identifies the scope of the multicast address. The bit group ID identifies the multicast group. Similar to multicast addresses, anycast addresses identify a set of interfaces. However, packets are sent to only one of the interfaces, not to all interfaces. Anycast addresses are allocated from the normal unicast address space and cannot be distinguished from a unicast address in format.
Therefore, each member of an anycast group must be configured to recognize certain addresses as anycast addresses. Addressing is the area where most of the differences between IP version 4 IPv4 and IPv6 exist, but the changes are largely about the ways in which addresses are implemented and used. IPv6 has a vastly larger address space than the impending exhausted IPv4 address space.
Each extra bit given to an address doubles the size of the address space. IPv4 has been extended using techniques such as Network Address Translation NAT , which allows for ranges of private addresses to be represented by a single public address, and temporary address assignment.
Although useful, these techniques fall short of the requirements of novel applications and environments such as emerging wireless technologies, always-on environments, and Internet-based consumer appliances. In addition to the increased address space, IPv6 addresses differ from IPv4 addresses in the following ways:. Includes a scope field that identifies the type of application that the address pertains to. Does not support broadcast addresses, but instead uses multicast addresses to broadcast a packet.
All IPv6 addresses are bits long, written as 8 sections of 16 bits each. They are expressed in hexadecimal representation, so the sections range from 0 to FFFF. Sections are delimited by colons, and leading zeroes in each section may be omitted. If two or more consecutive sections have all zeroes, they can be collapsed to a double colon.
IPv6 addresses consist of 8 groups of bit hexadecimal values separated by colons :. IPv6 addresses have the following format:. Each aaaa is a bit hexadecimal value, and each a is a 4-bit hexadecimal value.
Following is a sample IPv6 address:. You can compress bit groups of zeros to double colons :: as shown in the following example, but only once per address:. An IPv6 address prefix is a combination of an IPv6 prefix address and a prefix length.
The ipv6-prefix variable follows general IPv6 addressing rules. The prefix-length variable is a decimal value that indicates the number of contiguous, higher-order bits of the address that make up the network portion of the address.
Changes in source AS and destination AS are not immediately reflected in exported flows. In configuration commands, the protocol family for IPv6 is named inet6. In the configuration hierarchy, instances of inet6 are parallel to instances of inet , the protocol family for IPv4. In general, you configure inet6 settings and specify IPv6 addresses in parallel to inet settings and IPv4 addresses.
On SRX Series devices, on configuring identical IPs on a single interface, you will not see a warning message; instead, you will see a syslog message. Help us improve your experience. Let us know what you think. Do you have time for a two-minute survey?
Maybe Later. Understanding IPv4 and IPv6 Protocol Family IPv4 addresses are bit numbers that are typically displayed in dotted decimal notation and contains two primary parts: the network prefix and the host number. Understanding IPv4 Addressing IPv4 addresses are bit numbers that are typically displayed in dotted decimal notation. Class D is reserved for Multicasting. In multicasting data is not destined for a particular host, that is why there is no need to extract host address from the IP address, and Class D does not have any subnet mask.
IP addresses in this class ranges from Like Class D, this class too is not equipped with any subnet mask. IPv4 - Address Classes Advertisements.
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