How to recognise a VMware's virtual machine by its MAC address?. How to detect a Virtual Machine by its MAC address?.MAC address randomization in WiFi probe requests.How could I get MAC address of my website visitor?.Is MAC address assigned permanently, or it could be changed?.What's the difference between EUI-48 and MAC-48?.What is the structure of a MAC address?.What is an Individual Address Block (IAB)?.What types of assignments are you tracking?.What is a 36-bit Organizationally Unique Identifier (OUI-36)?.What is an Organizationally Unique Identifier (OUI)?.What are a universal address and a local administered address?.Very Nice" via Cisco Forum "Very Nice! It was completely useful for me.Pricing Documentation → Table of contents Request all who were helped by this post to Rate the author for his splendid work." via Cisco Forum "In the words of Borat Nice. I took lot of time and did many mistakes, that's why I failed for the first time, but once I see this post, I thought I have found some magical tricks of subnetting." via Cisco Forum "You deserve points for this post dude. This has got to be the most concise and least brain cell damaging explanation I've come across to figure out the subnets when using prefix notation." via Cisco Forum "Great, Keep it up! Your easy and quick method helped me a lot to pass CCNA. Great job." via Cisco Forum "I wanted to thank you for posting this. Using your technique I'm able to answer subnetting questions in 20 sec in my head. Guys, I recommend this subnetting tutorial." Forum Admin, "I wanted to thank the original poster for this information.reading this finally made it click and solved the mystery of subnetting for me and was instrumental in passing the CCNA yesterday." via Cisco Forum "I just passed the CCENT test. I use GNS3 and Dynamips Greaaaaaaaaaaaat" Fayda, GNS3 Configuration Guide comments "Chris, I just visited your blog and I want to congratulate you on your effort. Good work, if you have some tips for CCNA please post. This is completely invaluable information." Brad, GNS3 Configuration Guide comments "Hi, just tested it. Thanks so much for not only the tip, but the detailed tutorial on how to setup and actually use GNS3. I kept thinking to myself, if only there was a better way. I was going to actually buy some lame ass simulator software or buy a bunch of cisco equipment to prepare for my CCNA. "Can I just say, I am absolutely in LOVE with you and this blog right now. Only the remaining 5 bits of the 9 top bits will overlap (as the last 23 bits are used for the second half of Multi-cast MAC address) Regarding your point about 512 possible overlaps, I think we only have to worry about the 224.0.0.0 - 239.255.255.255 range when it comes to multi-casts as it's the reserved range for this purpose. Hi, thanks for explaining the MAC calculations. Basically any IP address with 40.35.1 or 168.35.1 as the last three octets carry the same multicast MAC address so you have potentially 32 addresses with the same multicast MAC address! So 192.168.35.1 has a multicast MAC address of 01-00-5E-28-23-01.Ĭan you spot an issue here? Hopefully you can. Our multicast MAC address is now 01-00-5E-28-23-01 In this example the value is 1 which equals 0x01. To calculate the value of ZZ take the fourth octet and convert it to hex. Our multicast MAC address is now 01-00-5E-28-23-ZZĤ. In this example the value is 35 which equals 0x23. To calculate the value of YY take the third octet and convert it to hex. Our multicast MAC address is now 01-00-5E-28-YY-ZZģ. In this example, the value of 168 is greater than 128 so we subtract 128 from 168 to give us a value of 40. If the value of the second octet is greater than 128 then subtract 128 from the second octet. To calculate the value of XX take the second octet. Start with a half-filled multicast MAC address of 01-00-5E-XX-YY-ZZĢ. Let us try and convert 192.168.35.1 to a multicast MAC addressġ. Therefore it must follow that a value of 6 in the second octet must be the same as 134 in the second octet as the high-order bit (i.e. If you think about this we are not using the high order bit in the second octet which carries a value of 128. To do this we need to convert the last 23 bits of the IP address in question. The first half of a multicast MAC address is 01-00-5E so we need to work out the second half. It's been a while but here's a quick post on how to calculate a multicast MAC address from an IP address.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |