{"id":33142,"date":"2019-10-31T21:50:58","date_gmt":"2019-10-31T18:50:58","guid":{"rendered":"https:\/\/prohoster.info\/blog\/printsipy-raboty-protokola-pim\/"},"modified":"2019-10-31T21:50:58","modified_gmt":"2019-10-31T18:50:58","slug":"printsipy-raboty-protokola-pim","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sq\/blog\/administrirovanie\/printsipy-raboty-protokola-pim","title":{"rendered":"Parimet e funksionimit t\u00eb protokollit PIM","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Protokolli PIM \u00ebsht\u00eb nj\u00eb grup protokollesh p\u00ebr transmetimin e multicast-it n\u00eb rrjet midis routerave. Marr\u00ebdh\u00ebniet e fqinj\u00ebsis\u00eb krijohen n\u00eb m\u00ebnyr\u00eb t\u00eb ngjashme si n\u00eb rastin e protokolleve dinamike t\u00eb routing-ut. PIMv2 d\u00ebrgon mesazhe Hello \u00e7do 30 sekonda n\u00eb adres\u00ebn e multicast-it t\u00eb rezervuar 224.0.0.13 (All-PIM-Routers). Mesazhi p\u00ebrmban Timers t\u00eb mbajtjes \u2014 zakonisht \u00ebsht\u00eb 3.5*Hello Timer, q\u00eb do t\u00eb thot\u00eb 105 sekonda si parazgjedhje.
\n\"Parimet<\/a><\/noindex>
\n PIM p\u00ebrdor dy moda kryesore pune \u2014 Dense dhe Sparse mode. Le t\u00eb fillojm\u00eb me Dense mode. <\/a><\/noindex>
\nP\u00ebrgjigjet e Distribucionit t\u00eb Bazuar n\u00eb Burim.<\/b>
\nModaliteti i Dense-mode \u00ebsht\u00eb i arsyesh\u00ebm p\u00ebr t'u p\u00ebrdorur n\u00eb rastin e nj\u00eb numri t\u00eb madh klient\u00ebsh nga grupe t\u00eb ndryshme multicast. Kur router-i merr trafik multicast, ai e kontrollon fillimisht at\u00eb n\u00eb rregullin RPF. RPF \u2014 ky rregull p\u00ebrdoret p\u00ebr t\u00eb verifikuar burimin e multicast-it me tabel\u00ebn e routing-ut unicast. Duhet q\u00eb trafiku t\u00eb vij\u00eb n\u00eb at\u00eb nd\u00ebrfaqe, p\u00ebr t\u00eb cil\u00ebn ky host \u00ebsht\u00eb i fshehur sipas tabel\u00ebs s\u00eb routing-ut unicast. Ky mekaniz\u00ebm zgjidh problemin e krijimit t\u00eb cikleve gjat\u00eb transmetimit t\u00eb multicast-it.
\n \"Parimet<\/a><\/noindex>
\nR3 nga mesazhi multicast m\u00ebson burimin e multicast-it (Source IP) dhe verifikon dy rrug\u00eb nga R1 dhe R2 sipas tabel\u00ebs s\u00eb tij unicast. Rruga nga ai nd\u00ebrfaqe, n\u00eb t\u00eb cil\u00ebn tregon tabela (R1 p\u00ebr n\u00eb R3), do t\u00eb kaloj\u00eb m\u00eb tej, nd\u00ebrsa rruga nga R2 do t\u00eb bllokohet, sepse p\u00ebr t\u00eb arritur te burimi i multicast-it, duhet t\u00eb d\u00ebrgohen paketa p\u00ebrmes S0\/1.
\nPyetja \u00ebsht\u00eb, \u00e7far\u00eb do t\u00eb ndodh\u00eb n\u00ebse keni dy rrug\u00eb ekuivalente me metrik\u00eb t\u00eb nj\u00ebjt\u00eb? N\u00eb k\u00ebt\u00eb rast, router-i do t\u00eb zgjedh\u00eb sipas next-hop p\u00ebr k\u00ebto rrug\u00eb. Ai me adres\u00ebn m\u00eb t\u00eb lart\u00eb IP do t\u00eb fitoj\u00eb. N\u00ebse \u00ebsht\u00eb e nevojshme t\u00eb ndryshohet kjo sjellje, mund t\u00eb p\u00ebrdoret ECMP. Lexoni m\u00eb shum\u00eb. k\u00ebtu<\/a><\/noindex>.
\nPas verifikimit t\u00eb rregullit RPF, router-i d\u00ebrgon paket\u00ebn multicast t\u00eb gjith\u00eb fqinj\u00ebve t\u00eb tij PIM, p\u00ebrve\u00e7 atij nga i cili \u00ebsht\u00eb pranuar kjo paket\u00eb. Routerat e tjer\u00eb PIM p\u00ebrs\u00ebrisin k\u00ebt\u00eb proces. Rruga q\u00eb ka ndjekur paketa multicast nga burimi deri te pranuesit p\u00ebrfundimtar, formon nj\u00eb pem\u00eb, e cila quhet \u2014 source-based distribution tree, shortest-path tree (SPT), source tree. Tri emra t\u00eb ndrysh\u00ebm, zgjidhni cilin t\u00eb doni.
\nSi t\u00eb zgjidhni \u00e7\u00ebshtjen kur disa routera nuk duan nj\u00eb rrjedh\u00eb t\u00eb caktuar multicast dhe nuk ka ask\u00ebnd p\u00ebr ta d\u00ebrguar at\u00eb, nd\u00ebrsa nj\u00eb router m\u00eb i lart\u00eb po e d\u00ebrgon. P\u00ebr k\u00ebt\u00eb \u00ebsht\u00eb krijuar mekanizmi Prune.
\nMesazhi Prune.<\/b>
\nP\u00ebr shembull, R2 do t\u00eb vazhdoj\u00eb t\u00eb d\u00ebrgoj\u00eb multicast n\u00eb R3, megjith\u00ebse R3 sipas rregullit RPF e bllokon at\u00eb. Pse t\u00eb ngarkoni kanalin? R3 d\u00ebrgon mesazhin PIM Prune dhe R2, pas marrjes s\u00eb k\u00ebtij mesazhi, do t\u00eb heq\u00eb nd\u00ebrfaqen S0\/1 nga lista (outgoing interface list) p\u00ebr k\u00ebt\u00eb rrjedh\u00eb, lista e nd\u00ebrfaqeve nga t\u00eb cilat duhet t\u00eb d\u00ebrgohet ky trafik. <\/p>\n

M\u00eb posht\u00eb \u00ebsht\u00eb nj\u00eb definicion m\u00eb formal i nj\u00eb mesazhi PIM Prune:
\nMesazhi PIM Prune d\u00ebrgohet nga nj\u00eb router te nj\u00eb router tjet\u00ebr p\u00ebr ta b\u00ebr\u00eb router-in e dyt\u00eb t\u00eb heq\u00eb lidhjen n\u00eb t\u00eb cil\u00ebn \u00ebsht\u00eb pranuar Prune nga nj\u00eb (S,G) SPT t\u00eb caktuar.<\/p><\/blockquote>\n

\nPas marrjes s\u00eb mesazhit Prune, R2 vendos timer-in Prune n\u00eb 3 minuta. Pas tre minutash ai do t\u00eb filloj\u00eb t\u00eb d\u00ebrgoj\u00eb trafik s\u00ebrish, deri sa t\u00eb marr\u00eb nj\u00eb mesazh tjet\u00ebr Prune. Kjo \u00ebsht\u00eb n\u00eb PIMv1.
\nNd\u00ebrsa n\u00eb PIMv2 \u00ebsht\u00eb shtuar timer-i State Refresh (me parazgjedhje 60 sekonda). Sa her\u00eb q\u00eb \u00ebsht\u00eb d\u00ebrguar mesazhi Prune nga R3, ky timer aktivizohet n\u00eb R3. Pas skadimit t\u00eb k\u00ebtij timer-i, R3 do t\u00eb d\u00ebrgoj\u00eb mesazhin State Refresh, i cili do t\u00eb reshtoj\u00eb timer-in Prune 3-minut\u00ebsh n\u00eb R2 p\u00ebr k\u00ebt\u00eb grup.
\nArsyet p\u00ebr d\u00ebrgimin e mesazhit Prune:<\/p>\n