First 24 bits of multicast address is always "01:00:5E". Put 25th bit as "0"
Last 23 bits is 0000000 00000000 00000101 So next 24 bits is 00000000 00000000 00000101 The multicast mac address is 01:00:5E:00:00:00:05 With regards Kings On Thu, Dec 23, 2010 at 7:12 PM, Bruno <[email protected]> wrote: > Sorry Kingsley, I didn`t understand that > > 224.0.0.5 in binary is: > 11100000 00000000 0000000*0* 00000101 > > As you said, the 25th bit is 0 as I can see > But I didn`t get from now on > > > On Thu, Dec 23, 2010 at 11:31 AM, Kingsley Charles < > [email protected]> wrote: > >> First 24 bits is 01:00:5E. The 25th bit is "0". The last 23 bits are the >> last 23 bits of the Multicast IP address. >> >> >> >> With regards >> Kings >> >> On Thu, Dec 23, 2010 at 6:00 PM, Bruno <[email protected]> wrote: >> >>> I know that there is a special block that IANA set aside for the vendor >>> part (1st 3 octets) of a multicast MAC address: 00:00:5E. (The addresses >>> above start with 01 instead of 00 because the broadcast/multicast bit is >>> set. Since this vendor block was set aside for multicast, they will really >>> always start off with 01:00:5E.) The rest of the address is somehow >>> calculated from the IP address >>> >>> Any thoughts? >>> >>> >>> On Thu, Dec 23, 2010 at 10:27 AM, Bruno <[email protected]> wrote: >>> >>>> Taking OSPF as an example, how could they say that the packet sent to >>>> 224.0.0.5 will have destination MAC-address 0100.5e00.0005 ? >>>> Is there any calculation method I should be aware of >>>> >>>> Any thought? >>>> >>>> -- >>>> Bruno Fagioli (by Jaunty Jackalope) >>>> Cisco Security Professional >>>> >>> >>> >>> >>> -- >>> Bruno Fagioli (by Jaunty Jackalope) >>> Cisco Security Professional >>> >>> _______________________________________________ >>> For more information regarding industry leading CCIE Lab training, please >>> visit www.ipexpert.com >>> >>> >> > > > -- > Bruno Fagioli (by Jaunty Jackalope) > Cisco Security Professional >
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