The last few blogs in my series on IPv6 have focused on solicited-node multicast, which provides the functionality for Neighbor Discovery in IPv6 addressing. We ended the last blog with a cliffhanger, asking, “In IPv6, how do we find the Layer 2 MAC address associated with a Layer 3 IPv6 address?”
Time to put the pieces together
In this series of blogs, I have laid out all the varying puzzle pieces needed to answer this question. Let’s start putting those puzzle pieces together.
In this blog, we learned that, if a device has an IPv6 global address of 2001:DB8::AB:1/64, then, according to RFC 4291, it must also “compute and join” the IPv6 solicited-node multicast address FF02::1:FFAB:1.
By the same logic, that means the node associated with the IPv6 address of 2001:DB8::AB:2 must “compute and join” the IPv6 solicited-node multicast address FF02::1:FFAB:2.
So our first puzzle piece gets us to here:
But so what? How does that get us any closer to getting the DMAC associated with Router B’s IPv6 global unicast address? All it did was give us a multicast address that this IPv6 unicast address must join.
Let’s add another piece of the puzzle. From this Continue reading
In a previous blog, we looked at the basics of IPv6 solicited-node multicast. Going back to our Router A and Router B environment, if we sniff the wire while pinging from Router A’s IPv6 address to Router B’s IPv6 address, what will we see? Spoilers! Suffice it to say we will see some IPv6 solicited-node multicast very much in action.
Ping in IPv4
Before we jump into IPv6, let’s first do an IPv4 ping from Router A to Router B. When we sniff the wire we can review the mechanisms of how IPv4 does all of this on the wire.
When ping 10.10.10.2 is entered on Router A, the router knows it is being asked to build an ICMP echo request message and put it “out on the wire” with a destination IP address of 10.10.10.2. But in order to make the request “ready” to put out on the wire to get to 10.10.10.2, Router A needs more than simply the destination IPv4 address.
For the purposes of this post, we will look at four things the router needs before sending the ICMP echo request out on the wire. These Continue reading
Solicited-node multicast: I stumbled and tripped a bunch over this one in the beginning. Well, that isn’t 100% true. Admittedly, at first, I really just ignored it, which really got in the way of my understanding some of the fundamentals of Neighbor Discovery Protocol (NDP).
But before we jump into solicited-node multicast, let’s review link-local scope multicast addresses.
Multicast is all around you
Multicast is all around your current IPv4 network. You might not think so if you haven’t enabled IP multicast routing and PIM, but it’s there. Pretty much everywhere you turn, it’s there.
Let’s return to our RouterA/RouterB environment. But let’s have IPv4 only running right now, like probably a lot of your routers in your environment.
Show IP interface
This is often an overlooked command, which is a shame because there is a great deal of very useful information that is given in the output. For now, we’re going to focus on the line “multicast reserved groups joined” and ignore all the other lines.
See? Lots and lots of multicast! To be specific, lots of “Local Network Control Block (224.0.0.0 – 224.0.0.255 (224.0.0/24),” according to the Internet Continue reading
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IPv6 solicited-node multicast somtimes seems to confuse those new to IPv6 in the beginning. I think this is because it seems so foreign and new. In this post, we will explore exactly what IPv6’s solicited-node multicast is and the rules of creating such an address as told to us by RFC 4291.
However, before we start on what’s new and different, let’s look at what solicited-node multicast has in common with IPv4 and IPv6 constructs that we already know.
In this blog post, we looked at IPv6 link-local scope multicast addresses. One of the examples was FF02::A. This address is for all devices on a wire that want to “talk” EIGRP with one another.
Focusing specifically on FF02::A and how routers join it, we can see and say three things:
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In 2017, the Internet Society unveiled the 2017 Global Internet Report: Paths to Our Digital Future. The interactive report identifies the drivers affecting tomorrow’s Internet and their impact on Media & Society, Digital Divides, and Personal Rights & Freedoms. In February 2018, we interviewed two stakeholders – Cyrating, a cybersecurity ratings agency, and Niel Harper, Senior Manager, Next Generation Leaders at the Internet Society – to hear their different perspectives on the forces shaping the Internet.
Niel Harper is a Young Global Leader at the World Economic Forum. He has more than 20 years of experience in the areas of telecoms management, cybersecurity, IT governance and strategy, ICT policy research and advisory services, and program management. (You can read Cyrating’s interview here).
The Internet Society: Experts predict an increase of frequency and impact of cyberattacks. What form are they likely to take in the future?
Niel Harper: In the foreseeable future, attackers are likely to fall under three categories: organized criminals seeking to profit from malicious online activities, online protesters (also known as hacktivists), and governments who target their own citizens or target other governments, whether for cyberespionage or cyberwarfare.
Criminals will continue to become more organized, selling Continue reading