{"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\/hu\/blog\/administrirovanie\/printsipy-raboty-protokola-pim","title":{"rendered":"A PIM protokoll m\u0171k\u00f6d\u00e9si elvei","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

A PIM protocol is a set of protocols for multicast transmission over a network between routers. Neighbor relationships are built similarly to dynamic routing protocols. PIMv2 sends Hello messages every 30 seconds to the reserved multicast address 224.0.0.13 (All-PIM-Routers). The message contains Hold Timers \u2014 usually set to 3.5 * Hello Timer, which defaults to 105 seconds.
\n\"A<\/a><\/noindex>
\n PIM uses two main operating modes \u2014 Dense and Sparse mode. Let's start with Dense mode. <\/a><\/noindex>
\nSource-Based Distribution Trees.<\/b>
\nThe dense-mode is advisable to use in cases with a large number of clients from various multicast groups. When a router receives multicast traffic, it first checks it against the RPF rule. RPF \u2014 this rule is used to verify the multicast source against the unicast routing table. The traffic must come in on the interface that corresponds to the host in the unicast routing table. This mechanism solves the problem of loop formation during multicast transmission.
\n \"A<\/a><\/noindex>
\nR3 learns the source of the multicast from the multicast message (Source IP) and checks two streams from R1 and R2 against its unicast table. The stream from the interface indicated by the table (R1 to R3) will be forwarded, while the stream from R2 will be dropped, since packets must be sent via S0\/1 to reach the multicast source.
\nWhat happens if you have two equivalent routes with the same metric? In this case, the router will choose based on the next-hop of these routes. The one with the higher IP address wins. If you need to change this behavior, you can use ECMP. More details itt<\/a><\/noindex>.
\nAfter validating the RPF rule, the router sends the multicast packet to all its PIM neighbors, except for the one from whom it received the packet. Other PIM routers repeat this process. The path that the multicast packet travels from source to final recipients forms a tree called the source-based distribution tree, shortest-path tree (SPT), or source tree. Three different names, choose any.
\nHow to address the issue where certain routers do not need a particular multicast stream and there is no one to send it to, while a higher-level router is sending it? The Prune mechanism was invented for this.
\nPrune Message.<\/b>
\nP\u00e9ld\u00e1ul az R2 tov\u00e1bbra is multicastot k\u00fcld R3-nak, b\u00e1r R3 az RPF szab\u00e1ly szerint elt\u00e1vol\u00edtja azt. Mi\u00e9rt terhelj\u00fck a kapcsolatot? Az R3 PIM Prune \u00fczenetet k\u00fcld, \u00e9s az R2, miut\u00e1n megkapta ezt az \u00fczenetet, elt\u00e1vol\u00edtja az S0\/1 interf\u00e9szt az adott forgalom kimeneti interf\u00e9szlist\u00e1j\u00e1r\u00f3l. <\/p>\n

Az al\u00e1bbiakban egy form\u00e1lisabb meghat\u00e1roz\u00e1s a PIM Prune \u00fczenetr\u0151l:
\nA PIM Prune \u00fczenetet az egyik router k\u00fcldi el a m\u00e1sodik routernek, hogy arra \u00f6szt\u00f6n\u00f6zze, hogy t\u00e1vol\u00edtsa el a Prune-t fogad\u00f3 linket egy adott (S,G) SPT-b\u0151l.<\/p><\/blockquote>\n

\nA Prune \u00fczenet meg\u00e9rkez\u00e9se ut\u00e1n az R2 3 percre be\u00e1ll\u00edtja a Prune id\u0151z\u00edt\u0151t. H\u00e1rom perc eltelt\u00e9vel \u00fajra megkezdi a forgalom k\u00fcld\u00e9s\u00e9t, am\u00edg nem kap \u00fajabb Prune \u00fczenetet. Ez a PIMv1.
\nA PIMv2-ben hozz\u00e1adt\u00e1k az State Refresh id\u0151z\u00edt\u0151t (alap\u00e9rtelmezett 60 m\u00e1sodperc). Amint Prune \u00fczenetet k\u00fcld az R3, elindul ez az id\u0151z\u00edt\u0151 az R3-on. Ennek az id\u0151z\u00edt\u0151nek a lej\u00e1rta ut\u00e1n az R3 State Refresh \u00fczenetet k\u00fcld, amely vissza\u00e1ll\u00edtja az R2 Prune T\u00e1rcs\u00e1z\u00e1si id\u0151z\u00edt\u0151t a csoport sz\u00e1m\u00e1ra.
\nA Prune \u00fczenet k\u00fcld\u00e9s\u00e9nek okai:<\/p>\n