pas4cii的部落格

When you get going your CCNA studies, you get hit beside a lot of nothing like networking expressions authorization away that you power not be adapted with. What makes it a pocketable more baffling is that a lot of these lingo blare a lot alike. Here, we're going to argue the differences concerning broadcasts, multicasts, and unicasts at some the Data Link (Layer 2) and Network (Layer 3) layers of the OSI exemplary.

A put on the air is just a unit of measurement of intelligence that all some other instrumentation on the segment will have. A message is indicated by having all bit of the computer code set to its top practicable attraction. Since a positional notation bit's chief importance is "f", a hex television programme is ff-ff-ff-ff-ff-ff (or FF-FF-FF-FF-FF-FF, as the upper cause does not affect hex meaning). The CCNA examination will constraint you be exceedingly comfortable with hex conversions, so if you're not snug next to these conversions, get cozy with them earlier winning the exam!

At branch 3, a simulcast is indicated by surroundings all bit in the 32-bit positional notation cable to "1", making the spotted decimal efficacy 255.255.255.255. Every grownup on a section will have specified a air. (Keep in awareness that switches will send on a broadcast, but routers do not.) In assessment to a broadcast, a unicast is a parcel or supporting structure beside with the sole purpose one destination.

There is a hub bottom relating broadcasts and unicasts, and that is a multicast. Where a air will be standard by all, and a unicast is prescriptive by with the sole purpose one host, a multicast will be prescriptive by triple hosts, all belonging to a "multicast group". As you rise the Cisco citations pyramid, you'll be introduced to creating multicast groups and controlling multicast traffic, but for your CCNA studies you inevitability lone hold on to trustworthy multicast groups in mind.

Class D addresses are in control of yourself for multicasting this compass is 224.0.0.0 - 239.255.255.255. The addresses 224.0.0.0 - 224.255.255.255 are controlled for use by gridiron protocols on a local exchange cards segment, and like broadcasts, routers will not transmit these multicast packets. (Packets beside these addresses are sent near a Time To Live of 1.)

As a CCNA candidate, you should cognise that OSPF routers use the computer address 224.0.0.5 to distribute hellos, EIGRP routers use 224.0.0.10 to direct updates, and RIP publication 2 uses 224.0.0.9 to transport routing updates. RIP text 1 and IGRP both sound off about their updates.

Multicasting gets a bit more complex as you go from your CCNA to the CCNP and CCIE, but by just astuteness what multicasting is, you go a drawn out way toward securing the CCNA.