ip v6.10

IP v6

IP v6

Tc gi: L Anh cPh lc: nh dng ca trng Option v PayloadChng ny m t nh dng ca marshaled option v demand payload.

c im chung ca option v payload:

Code class c 128 bit nh danh. Trong cch hin thc hin nay, y l con s c chn ngu nhin, nhng trong tng lai, nh danh y c th l mt MD5 fingerprint c xc nhn bi mi code class.

C chung trng Active Type, nhm phc v cho vic phn bit s khc nhau gia cc loi nh dng marshaled option v system payload.

I. Ipv6 OptionIpv6 cn mi option phi c mt loi gi tr. 2 bit cao nht ca gi tr ny l ch th ca tt c cc Ipv6 Nodes. Nu cc node ny khng hiu c opyion th n s b qua option v tip tc x l packet. Bit th 3 dng thng bo cho cc node bit ni dung ca option, ni dung ny c th b thay i trn ng i. Cc giao thc bo mt end-to-end cn thng tin ny khi tnh ton checksums.

Length field: Gi tr ca field ny ph thuc vo s trng thi c a vo option.

Padding field: m bo s sp xp thch hp cv byte trong cc header. Ipv6 c t padding field trong option field. Ipv6 cung cp 2 lai: Pad1 option v PadN option.

II. Marshaled optionMarshaled option cha gi tr trng thi cho cc on code c kh nng lp trnh c xc nh bi trng nh danh. Marshaled option c gi tr l 54. IPv6 node s phi b qua marshaled option nu n khng hiu.

Address of last active node (128 bit) : c thm vo gi option ny nhm h tr cho ANTS-style, l giao thc demand-loading. Khi mt node request code t node k cn pha trc th trng ny s cung cp a ch y.

gim chi ph cho vic demultiplexing mt packet ti active processor hoc ti mt l trnh IPv6 mc nh no , marshaled option phi l option u tin trong hop-by-hop option header. Thm vo , gia marshaled option vi phn u ca header phi khng c mt padding no. Hop-by-hop header cng phi l extension header u tin trong packet. Nhng iu trn s lm gim chi ph cho vic demultiplexing. L do l hop-by-hop header, marshaled option c cha cc thng tin quan trng ch th ban u.

Ri ro cho vic dng field option trong hop-by-hop option header vn chuyn gi tr trng thi l s c t IPv6 s ngn cc IPv6 nodes phn mnh hop-by-hop header. V th, thm ch packet b phn mnh, gi tr ca trng thi trong marshaled option cng c th c dng thc thi code ti mi node. Vn ch code ca mt packet c th c thc thi hn mt ln khi packet i qua mi node, bi v code s c thc thi cho mi phn mnh. y c th l c li hoc c hi, ty thuc vo yu cu ca ng dng. Bi v s phn mnh ch c th xy ra ti source node, nn gii php tt nht l tt ch phn mnh ti source node.

III. System payloadC demand request v demand response s c vn chuyn trong cng 1 kiu payload, l active payload. Active payload c protocol value l 89. Ch c AIPv6 node mi truyn payload t ni ny n ni khc. Byte u tin ca payload l c t chiu di ca payload ny theo n v 8 octec, khng bao gm field u tin. V nhu cu trong tng lai, ngi ta ngh 2 ensure byte dng cho active networking. C ngh to ring hn mt active ayload cho acitve networking.

a. Demand request

Active type value = 2

Khi mt AIPv6 node nhn mt marshaled option m n khng thy code tng ng (corresponding code) th n s gi mt demand request payload ti upstream active node k cn. Upstream active node k cn ny c xc nh trong marshaled option. Trng nh danh (identifier field c t loi code m requesting node cn).

Demand request payload c thit k ph hp, tc l nh hn dung lng ti a ca option n c kh nng hin thc.

b. Demand response

Total (Tot) (4 bit): s phn mnh ca code.Sequence (Seq) (4 bit): th t cc phn mnh ca bytecodes trong packet. Phn mnh u tin c gi tr l 0.