![]() convert octet back to hexadecimal: 01010000 -> 50.convert the first octet from hexadecimal to binary: 52 -> 01010010.reformat to IPv6 notation 5274:f2ff:feb1:a87f.take the mac address: for example 52:74:f2:b1:a8:7f.Here’s the conversion process step by step: This link-local IPv6 is infered from the NIC’s mac address.Ī mac address is 48 bits, an IPv6 address is 128 bits. ![]() Instead of getting an address via DHCP, a NIC will hop on the network with a link-local IPv6 address and with this will have to ability to do further configuration automatically (soliciting neighbors, router, et cetera). In the next blog post we’ll continue the examination and explanation of the Men&Mice IPv6 cheat-sheet, and take a good look at the IPv6 address space and the things you can do with it.Link-local IPv6 addresses are used as part of the IPv6 network auto-configuration process. Use Automation to Get More IP Information The final EUI-64 version of the MAC address C0:A1:B2:C3:D4:E5 thus becomes C2:A1:B2:FF:FE:C3:D4:E5. Lastly, invert the 7th bit: convert the first byte ( C0 in this case) to binary (resulting in 11000000), check the 7th bit ( 0) and flip it (to 1) and translate it back to hexadecimal (binary 11000010 becomes C2).Then insert FF:FE between them, making it C0:A1:B2:FF:FE:C3:D4:E5.First the 48-bit MAC address needs to be separated into two 24-bit parts: C0:A1:B2:C3:D4:E5 becomes C0:A1:B2 C3:D4:E5.The conversion is needed because hardware MAC addresses are 48-bits long. Contains the IPv6 address of the destination node for which the packet is intended.Įxtended Unique Identifier (EUI-64, because it’s 64-bits long) is a new method with which IPv6 hosts can be automatically configured in DHCP. destination address: 128 bits long, same function as in IPv4.Contains the IPv6 address of the node originally sending the packet. source address: 128 bits long, same function as in IPv4.Decremented by one passing each node, and the packet is discarded when the value of hop limit reaches zero. hop limit: 8-bits long, formerly known in IPv4 as ‘time-to-live’.It shares its function (and values) with IPv4’s ‘protocol’ field, and as the name suggests specifies the type of the next header. (Extensions headers replace the ‘options’ field known from IPv4.) It’s set to zero when the packet carries a jumbo payload. Contains the size of the payload in octets ( remember those?) and can include extension headers. Useful for real-time applications, it signals the receiving node (routers or switches) to keep packets on the same path as to prevent them from being reordered. flow label: 20 bits long, and new to IPv6.ECN can be used to signal congestion on the network by marking it in the IPv6 header. The last two bits are for optional explicit congestion notifications (ECN). For example, streaming media like video and audio on a conference call can enjoy lower latency than non-critical traffic, such as web browsing. DSCP classifies the type of traffic carried by the packet for quality of service (QoS) purposes. The first 6 bits contain the differentiated services (DiffServ) designation of the packet, and is called differentiated services code point (DSCP). traffic class: 8 bits long, and replaces IPv4’s ‘type of service’ field.In case of IPv6 that is of course 6, making this field’s binary value 0110. It indicates the receiver the IP version to expect. version: 4 bits long, and corresponds to IPv4’s field of the same name.The IPv6 header is more streamlined: it contains 8 fields, compared to IPv4’s 14 fields. ![]() It’s smaller in size: IPv4 uses 32 bit binary numbers whereas IPv6 uses 128-bit binary numbers. When discussing the IPv6 header it’s inevitable to compare it to what came before: (Image credit: Wikipedia.) ![]() Let’s start with, just like an IPv6 packet does, the header. We’ll use our famed IPv6 cheat-sheet (also available as a lens cleaner - visit us at events to score one) as a guide, and examine each section in depth. Instead, let’s take a closer look at the IPv6 protocol itself. We’ve talked about it a lot (and some more and more) but this time we don’t want to discuss the merits or pitfalls of IPv6. IPv6 is increasingly not an option but a fact of life.
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