1IPv6, MPLSIPv6 History Next generation IP (AKA IPng) Intended to extend address space and routinglimitations of IPv4 Requires header change Attempted to include everything new in one change IETF moderated Based on Simple Internet Protocol Plus (SIPP)IPv6 Wish list 128-bit addresses Multicast traffic Mobility Real-time traffic/quality of service guarantees Authentication and security Autoconfiguration for local IP addresses End-to-end fragmentation Protocol extensions Smooth transition! Note Many of these functionalities have been retrofit into IPv4IPv6 Addresses 128-bit 3.4 x 1038 addresses (as compared to 4 x 109) Classless addressing/routing (similar to CIDR) Address notation String of eight 16-bit hex values separated by colons 5CFA:0002:0000:0000:CF07:1234:5678:FFCD Set of contiguous 0’s can be elided 5CFA:0002::CF07:1234:5678:FFCD Address assignment Provider-based geographic010 Region ID Provider ID Subscriber ID Subnet Host3 m n o p 125-m-n-o-pIPv6unassignedOtherMulticast address1111 1111Site local address1111 1110 11Link local address1111 1110 10Geographic multicast100Provider-based unicast010Novell IPX allocation0000 010ISO NSAP (Network Service Point) Allocation0000 0001Reserved (includes transition addresses)0000 0000Address typePrefixIPv4 Packet Format 20 Byte minimum Mandatory fields are not always used e.g. fragmentation Options are an unordered list of (name, value) pairsTTLsource addressdestination addressoptions (variable)version length offsetident 0 8 16 31hdr len TOSflagschecksumprotocolpad (variable)2IPv6 Packet Formatdestination address word 4options (variable number, usually fixed length)version flow label hop limitpayload length 0 8 16 31prioritynext headersource address word 1source address word 2source address word 3source address word 4destination address word 1destination address word 2destination address word 3IPv6 Packet Format 40 Byte minimum Mandatory fields (almost) always used Strict order on options reduces processing time No need to parse irrelevant optionsoptions (variable number, usually fixed length)version flow label hop limitpayload length 0 8 16 31prioritynext headersource address 4 words destination address 4 words IPv6 Packet Format Version 6 Priority and Flow Label Support service guarantees Allow “fair” bandwidth allocation Payload Length Header not included Next Header Combines options and protocol Linked list of options Ends with higher-level protocol header (e.g. TCP) Hop Limit TTL renamed to match usageIPv6 Extension Headers Must appear in order Hop-by-hop options Miscellaneous information for routers Routing Full/partial route to follow Fragmentation IP fragmentation info Authentication Sender identification Encrypted security payload Information about contents Destination options Information for destinationIPv6 Extension Headers Hop-by-Hop extension Length is in bytes beyond mandatory 8next header typevalue0 8 16 31lengthnext header 194Payload length in bytes0 8 16 310 0Jumbogram option (packet longer than 65,535bytes)Payload length in main header set to 0IPv6 Extension Headers Routing extension Up to 24 “anycast” addresses target AS’s/providers Next address tracks current target Strict routing requires direct link Loose routing allows intermediate nodesnext header # of addressesstrict/loose routing bitmap0 8 16 310 next address1 – 24 addresses3IPv6 Extension Headers Fragmentation extension Similar to IPv4 fragmentation 13-bit offset Last fragment mark (M) Larger fragment identification fieldnext header offsetident0 8 16 31reserved reserved MIPv6 Extension Headers Authentication extension Designed to be very flexible Includes Security parameters index (SPI) Authentication data Encryption Extension Called encapsulating security payload (ESP) Includes an SPI All headers and data after ESP are encryptedIPv6 Design Controversies Address length 8 byte Might run out in a few decades Less header overhead 16 byte More overhead Good for foreseeable future 20 byte Even more overhead Compatible with OSI Variable lengthIPv6 Design Controversies Hop limit 65,535 32 hop paths are common now In a decade, we may see much longer paths 255 Objective is to limit lost packet lifetime Good network design makes long paths unlikely Source to backbone Across backbone Backbone to destinationIPv6 Design Controversies Greater than 64KB data Good for supercomputer/high bandwidthapplications Too much overhead to fragment large datapackets 64 KB data More compatible with low-bandwidth lines 1 MB packet ties up a 1.5MBps line for morethan 5 seconds Inconveniences interactive usersIPv6 Design Controversies Keep checksum Removing checksum from IP isanalogous to removing brakes from a car Light and faster Unprepared for the unexpected Remove checksum Typically duplicated in data link andtransport layers Very expensive in IPv44IPv6 Design Controversies Mobile hosts Direct or indirect connectivity Reconnect directly using canonical address Use home and foreign agents to forward traffic Mobility introduces asymmetry Base station signal is strong, heard by mobile units Mobile unit signal is weak and susceptible to interference,may not be heard by base stationIPv6 Design Controversies Security Where? Network layer A standard service Application layer No viable standard Application susceptible to errors in networkimplementation Expensive to turn on and off How? Political import/export issues Cryptographic strength issuesTransition From IPv4 To IPv6 Not all routers can be upgradedsimultaneous no “flag days” How will the network operate with mixedIPv4 and IPv6 routers? Tunneling: IPv6 carried as payload inIPv4 datagram among IPv4 routersTunnelingA BEFIPv6IPv6IPv6 IPv6tunnelLogical view:Physical view:A BEFIPv6 IPv6 IPv6 IPv6IPv4 IPv4TunnelingA BEFIPv6 IPv6 IPv6 IPv6tunnelLogical view:Physical view:A BEFIPv6 IPv6IPv6IPv6CDIPv4 IPv4Flow: XSrc: ADest: FdataFlow: XSrc: ADest: FdataFlow: XSrc: ADest: FdataSrc:BDest: EFlow: XSrc: ADest: FdataSrc:BDest: EA-to-B:IPv6E-to-F:IPv6B-to-C:IPv6 insideIPv4B-to-C:IPv6 insideIPv4Multiprotocol label
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