Tag Archives: IPv4

IP Class is Now in Session

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You may have seen something making the rounds on Twitter this week about a couple of proposed drafts designed to alleviate the problems with IPv4 exhaustion by repurposing some old IP spaces that aren’t available for use right now. Specifically:

Ultimately, this is probably going to fail for a variety of reasons and looks like it’s more of a suggestion than anything else but I wanted to take a moment to talk about why this isn’t an effective way of fixing address issues.

Error Bearers

The first reason that the Schoen drafts are going to fail is because most of the operating systems in the world won’t allow you to use reserved spaces for a system address. Because we knew years ago that certain spaces were marked as non-usable the logic was configured into the system to disallow the use of those spaces. And even if the system isn’t configured to disallow that space there’s no guarantee the traffic is going to be transmitted.

Let’s take 127/8 as a good example. Was it a smart idea to mark 16 million addresses as loopback host-only space? Nope. But that ship has sailed and we aren’t going to be able to easily fix it. Too many systems will see any address starting with 127 in first octet and assume it’s a loopback address. In much the same way as people have been known to assume the entire 192/8 address space is RFC1918 reserved instead of 192.168.0.0/16. Logic rules and people making decisions aren’t going to trust any space being used in that manner. Even if you did something creative like using NAT and only using it internally you’re not going to be able to patch every version of every operating system in your organization.

We modify rules all the time and then have to spend years updating those modifications. Take area codes in North America for example. The old rules used to say that an area code had to have a zero or a one for the middle digit – ([2-9][0-1][2-9]) to use the Cisco UCM parlance. If your middle digit was something other than a zero or a one it wasn’t a valid NANP area code. As we began to expand the phone system in 1995 we changed those rules and now have area codes with all manner of middle numbers.

What about prefixes? Those follow rules too. NANP prefixes must not start with a zero or a one – (area code) [2-9]XX-XXXX is the way they are coded. Prefixes that start with a zero or a one are invalid and can’t be used. If we suddenly decided that we needed to open up the numbers in existing area codes and include prefixes that start with those forbidden numbers we would need to reset all the dialing rules in systems all over the country. I know that I specifically programmed my CUCM servers to send an immediate error if you dialed a prefix with a zero or a one. And all of them would have to be manually reconfigured for such a change.

In much the same way, the address spaces that are reserved today as invalid would need to be patched out of systems from home computers to phones to networking equipment. And even if you think you got it all you’re going to miss one and wonder why it isn’t working. Worse yet, it might even silently fail because you may be able to transmit data to 95% of the systems out there but some intermediate system may discard your packets as invalid and never tell you what happened. You’ll spend hours or days chasing a problem you may not even be able to fix.

Avoiding the Solutions

The easiest way to look at these proposals is by understanding that people are really, really, really in love with IPv4. Despite the fact that using the effort of the changes necessary to implement these reserved spaces would be better spent on IPv6 adoption we still get these things being submitted. There is a solution but people don’t want to use it. The modern Internet relies so much on the cloud that it would be simple to enable IPv6 in your provider space and use your engineering talent to help provide better adoption for that instead. We’re already seeing that all over places with address space has been depleted for a while now.

It may feel easier to spend more effort to revitalize the IPv4 space we all know and love. It may even feel triumphant when we’re able to reclaim address space that was wasted and use it for something productive instead of just teaching that you can’t configure devices with those spaces. And millions of devices will have IP address space to use, or more accurately there will be millions of addresses available to sell to people that will waste them anyway. Then what?

The short term gain from opening up IPv4 space at the expense of not developing IPv6 adoption is a fallacy that will end in pain. We can keep putting policy duct tape on the IPv4 exhaustion problem but we are eventually going to hit a wall we can’t overcome. The math doesn’t work when your address space is only 32 bits in total. That’s why IPv6 expanded the amount of information in the address space.

Sure, there have been mistakes in the way that IPv6 address space has been allocated and provisioned. Those mistakes would need to eventually be corrected and other configurations would need to be done in order to efficiently utilize the space. Again, the effort should be made to fix problems with a future-proof solution instead of trying our hardest to keep the lights on with the old system that’s falling apart for a few more years.

Tom’s Take

The race to find every last possible way to utilize the IPv4 space is exactly what I expected when we’re in the death throes of using it instead of IPv6. The easy solutions are done. The market and hunger for IPv4 space is only getting stronger. Instead of weaning the consumers off their existing setups and moving them to something future proof we’re feeding their needs for short term gains. If the purpose of this whole exercise was to get more address space to be rationed out for key systems to keep them online longer I might begrudgingly accept it. However, knowing that it would likely be opened up and fed to providers to be auctioned off in blocks to be ultimately wasted means all the extra effort is for no gain. These IETF drafts have a lot of issues and we’re better off letting them expire in May 2022. Because if we take up this cause and try to make them a reality we’re going to have to relearn a lot of lessons of the past we’ve forgotten.

It’s Time For IPv6, Isn’t It?

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I made a joke tweet the other day:

It did get lots of great interaction, but I feel like part of the joke was lost. Every one of the things on that list has been X in “This is the Year of X” for the last couple of years. Which is sad because I would really like IPv6 to be a big part of the year.

Ars Technica came out with a very good IPv6-focused article on January 3rd talking about the rise in adoption to 10% and how there is starting to be a shift in the way that people think about IPv6.

Old and Busted

One of the takeaways from the article that I found most interesting was a quote from Brian Carpenter of The University of Aukland about address structure. Most of the time when people complain about IPv6, they say that it’s stupid that IPv6 isn’t backwards compatible with IPv4. Carpenter has a slightly different take on it:

The fact that people don’t understand: the design flaw is in IPv4, which isn’t forwards compatible. IPv4 makes no allowance for anything that isn’t a 32 bit address. That means that, whatever the design of IPng, an IPv4-only node cannot communicate directly with an IPng-only node.

That’s a very interesting take on the problem that hadn’t occurred to me before. We’ve spent a lot of time trying to make IPv6 work with IPv4 in a way that doesn’t destroy things when the problem has nothing to do with IPv6 at all!

The real issue is that our aging IPv4 protocol just can’t be fixed to work with anything that isn’t IPv4. When you frame the argument in those terms you can start to realize why IPv4’s time is coming to an end. I’ve been told by people that moving to 128-bit addressing is overkill and that we need to just put another octet on the end of IPv4 and make them compatible so we can use things as they are for a bit longer.

Folks, the 5th octet plan would work exactly like IPv6 as far as IPv4 is concerned. The issue boils down to this: IPv4 is hard-coded to reject any address that isn’t exactly 32-bits in length. It doesn’t matter if your proposal is 33 bits or 256 bits, the result is the same: IPv4 won’t be able to directly talk to it. The only way to make IPv4 talk to any other protocol version would be extend it. And the massive amount of effort that it would take to do that is why we have things like dual stack and translation gateways for IPv6. Every plan to make IPv4 work a little longer ends in the same way: scrap it for something new.

New Hotness

Fresh from our take on how IPv4 is a busted protocol for the purposes of future proofing, lets take a look at what’s driving IPv6 right now. I got an email from my friend Eric Hileman, who runs a rather large network, asking me when he should consider his plans to transition to IPv6. My response was “wait for mobile users to force you there”.

Mobility is going to be the driving force behind IPv6 adoption. Don’t believe me? Grab the closest computing device to your body right now. I’d bet more than half of you reached for a phone or a tablet if you didn’t already have a smartwatch on your wrist. We are a society that is embracing mobile devices at an increasingly rapid rate.

Mobility is the new consumer compute. That means connectivity. Connectivity everywhere. My children don’t like not being able to consume media away from wireless access points. They would love to have a cellular device to allow them access to TV shows, movies, or even games. That generation is going to grow up to be the primary tech consumer in the next ten years.

In those intervening years, our tech infrastructure is going to balloon like never before. Smart devices will be everywhere. We are going to have terabytes of data from multiple sources flooding collectors to produce analysis that must be digested by some form of intelligence, whether organic or artificial. How do you think all that data is going to be transmitted? On a forty-year-old protocol with no concept of the future?

IPv6 has to become the network protocol to support future infrastructure. Mobility is going to drive adoption, but the tools and software we build around mobility is going to push new infrastructure adoption as well. IPv6 is going to be a huge part of that. Devices that don’t support IPv6 are going to be just like the IPv4 protocol they do support – forever stuck in the past with no concept of how the world is different now.

Tom’s Take

It’s no secret I’m an IPv6 champion. Even my distaste for NAT has more to do with its misuse with regard to IPv6 than any dislike for it as a protocol. IPv6 is something that should have been recognized ten years ago as the future of network addressing. When you look at how fast other things around us transform, like mobile computing or music/video consumption, you can see that technology doesn’t wait for stalwarts to figure things out. If you don’t want to be using IPv4 along with your VCR it’s time to start planning for how you’re going to use it.

 

 

IPv4? That Will Cost You

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ipvdollar

After my recent articles on Network Computing, I got an email from Fred Baker.  To say I was caught off guard was an understatement.  We proceeded to have a bit of back and forth about IPv6 deployment by enterprises.  Well, it was mostly me listening to Fred tell me what he sees in the real world.  I wrote about some of it over on Network Computing.

One thing that Fred mentioned in a paragraph got me thinking.  When I heard John Curran of ARIN speak at the Texas IPv6 Task Force meeting last December, he mentioned that the original plan for IPv6 (then IPng) deployment involved rolling it out in parallel with IPv4 slowly to ensure that we had all the kinks worked out before we ran out of IPv4 prefixes.  This was around the time the World Wide Web was starting to take off but before RFC 1918 and NAT extended the lifetime of IPv4.  Network engineers took a long hard look at the plans for IPv6 and rightfully concluded that it was more expensive to run IPv6 in conjunction with IPv4 and instead it was more time and cost effective to just keep running IPv4 until the day came that IPv6 transition was necessary.

You’ve probably heard me quote my old Intro to Database professor, Dr. Traci Carte.  One of my favorite lessons from her was “The only way to motivate people is by fear or by greed.”  Fred mentioned that an engineer at an ISP mentioned to him that he wanted to find a way to charge IPv4 costs back to the vendors.  This engineer wants to move to a pure IPv6 offering unless there is a protocol or service that requires IPv4.  In that case, he will be more than willing to enable it – for a cost.  That’s where the greed motivator comes into play.  Today, IPv6 is quickly becoming equivalent in cost to IPv4.  The increased complexity is balanced out by the lack of IPv4 prefixes.

What if we could unbalance the scales by increasing the cost of IPv4?  It doesn’t have to cost $1,000,000 per prefix.  But it does have to be a cost big enough to make people seriously question their use of IPv4.  Some protocols are never going to be ported to have IPv6 versions.  By making the cost of using them higher, ISPs and providers can force enterprises and small-to-medium enterprises (SMEs) to take a long hard look at why they are using a particular protocol and whether or not a new v6-enabled version would be a better use of resources.  In the end, cheaper complexity will win out over expensive ease.  The people in charge of the decisions don’t typically look at man-hours or support time.  They merely check the bottom line.  If that bottom line looks better with IPv6, then we all win in the end.

I know that some of you will say that this is a hair-brained idea.  I would counter with things like Carrier-Grade NAT (CGN).  CGN is an expensive, complicated solution that is guaranteed to break things, at least according to Verizon.  Why would you knowingly implement a hotfix to IPv4 knowing what will break simply to keep the status quo around for another year or two?  I would much rather invest the time and effort in a scaling solution that will be with us for another 10 years or more.  Yes, things my break by moving to IPv6.  But we can work those out through troubleshooting.  We know how things are supposed to work when everything is operating correctly.  Even in the best case CGN scenario we know a lot of things are going to break.  And end-to-end communications between nodes becomes one step further removed from the ideal.  If IPv4 continuance solutions are going to drain my time and effort they become as costly (or moreso) that implementing IPv6.  Again, those aren’t costs that are typically tracked by bean counters unless they are attached to a billable rate or to an opportunity cost of having good engineering talent unavailable for key projects.

Tom’s Take

Dr. Carte’s saying also included a final line about motivating people via a “well reasoned argument”.  As much as I love those, I think the time for reason is just about done.  We’ve cajoled and threatened all we can to convince people that the IPv4 sky has fallen.  I think maybe it’s time to start aiming for the pocketbook to get IPv6 moving.  While the numbers for IPv6 adoption are increasing, I’m afraid that if we rest on our laurels that there will be a plateau and eventually the momentum will be lost.  I would much rather spend my time scheming and planning to eradicate IPv4 through increased costs than I would trying to figure out how to make IPv4 coexist with IPv6 any longer.

Unlearning IPv4

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"You must unlearn what you have learned." -Yoda

“You must unlearn what you have learned.” -Yoda

As network rock stars, we’ve all spent the majority of our careers learning how to do things.  We learn how to address interfaces and configure routing protocols.  For many of those out there, technology has changed often enough that we often find ourselves need to retrain.  Whether it be a new version of an old protocol or an entirely new way of thinking about things, there will always come a time when it’s necessary to pick up new knowledge.  However, in the case of updated knowledge it’s often difficult to process.  That’s because the old way of doing things interposes itself in our brains while we’re learning to do it the new way.  How many times have you been practicing something only to hear a little voice in the back of your head saying, “That’s not right.  You should be doing it this way.”  In many ways, it’s like trying to reprogram the pathway in your brain that leads to the correct solution to your problem.

This is very apparent to me when it comes to learning how to configure and setup IPv6 on a network.  Those just starting out in the big wide world of IPv6 need to have some kind of reference point to start configuring things, so they tend to lean back on their IPv4 training in order to get started.  This can work for some applications.  For others, though, it can be quite detrimental to getting IPv6 running the way it should.  Instead of carrying forward the old way of doing things because “that’s just the way they should be done,” you need to start unlearning IPv4.  The little green guy in Empire Strikes Back hit the nail on the head.  The whiney farm boy had spent so much of his life convinced that something was impossible that he couldn’t conceive that someone could lift his starship out of a swamp with the Force.  He had to unlearn that lifting things with his mind was impossible.  Once you take that little step, nothing can stop you from accomplishing anything.

With that in mind, here are a few things that need to be unlearned from our days working with IPv4.  Note that this won’t be easy.  But nothing worth doing is ever easy.

Address Conservation – This one is the biggest stumbling block today.  Look at all the discussion we’ve got around point-to-point links and whether to address them with a /64 or a /127 bit mask.  People claim that addressing this link with a /64 wastes addresses.  To  quote the old guy in the desert from Star Wars, “It’s true, depending on your point of view.”  In a given /64, there are approximately 18 quadrillion addresses available (I’m rounding to make the math easy).  If you address a point-to-point link with a /64, you’re only going to be using 0.0000000000000000001% of those addresses (thats 1 * 10^-19).  To many, that’s a pretty big waste.  But with numbers that big, your frame of reference gets screwed up.  By example, take a subnet with 4,094 hosts, which today would need /20 in IPv4.  That’s about the biggest single subnet I can imagine creating.  If you address that 4,094 host subnet with a /64 in IPv6, you’d end up using 0.0000000000000002% (2 * 10^-16) of the address space.  Waste is all a matter of perspective.  On the other hand, by addressing a link with a bit mask beyond a /64, we break neighbor discovery and secure neighbor discovery and PIM sparse mode with embedded RP among other things.  We need to unlearn the address conservation mentality and instead concentrate on making our networks easier to configure and manage.

Memorizing IP addresses – I’m guilty of this.  I spend a lot of time working at the command line with IPv4, whether it be via telnet or SSH or even just plugging numbers into a GUI.  My CUCM systems are setup to use IP only.  I memorize the addresses of my servers, or in many cases try to make this as similar mnemonically to other systems to jog my memory about where to find them in IP space.  In IPv6, memorizing addresses is going to be impossible.  It’s hard enough for me to remember non-RFC1918 address space as it is with 4 octets of decimal numbers.  Now quadruple that and add in hex addressing.  And when it comes to workstations with SLAAC or DHCPv6 assigned addresses?  Forget about it.  Rather than memorizing address space, we’re going to need to start using DNS for communications between endpoints.  Yes, that means setting up DNS for all your routers and CUCM servers too.  It’s going to be a lot of extra work up front.  It’ll pay off in the long run, though.  I’m sure you’d much rather refer to CUCM1.local rather than trying to remember fe80::ba8d:12ff:fe0b:8aff every time you want to get to the phone server.

Subnet Masks – Never again will you need to see 255 in an IPv6 address unless it’s part of the address.  Subnet masking is dead and buried.  Instead, bit masks and slash notation rule the day.  This is going to be one of the most welcome changes in IPv6, but I think it’s going to take a long time to unlearn.  Not really as much for network engineers, but mainly for the people that have ancillary involvement with networking, such as the server people.  Think about the number of server admins that you’ve talked to that have memorized that the subnet mask of their network card is 255.255.255.0.  Now, ask them what that means. Odds are good they can’t tell you.  Worse, some of them might say that it’s a Class C subnet mask.  It’s a little piece of anecdotal information that they heard once when the network folks were talking that they just picked up.  Granted, most of the time the servers are going to be addresses with a /64 bit mask on the IPv6 address.  That’s still going to take a while to explain to the non-networking people.  No, you don’t need any more 255s in your address.  Yes, the /64 is the same as that, sort of.  No, there’s math involved.  Yes, I’ll take care of all the math.

Ships in the Night – As I said on my recent appearance on the Class C block podcast, I think it’s high time that networking vendors stop treating IPv4 and IPv6 like they are separate entities.  I know that I’ve spent the better part of this blog post talking about how IPv4 and IPv6 require a difference in application and not carrying across old habits and conventions.  The two protocols are more alike that they are different.  That means that we need to stop thinking of IPv6 as an afterthought.  Take a look at the CCIE.  There’s still a separate section for IPv6.  It feels like it was just a piece that was added on to the end of the exam instead of being integrated into the core lab.  Look at Kurt Bales’ review of the JNCIE lab that he took.  Specifically, the last bullet point.  You could be asked to configure something on either IPv4 or IPv6, or even both!  Juniper understands that the people taking the JNCIE today aren’t going to have the luxury of concentrating on just IPv4.  The world is going to require us to use IPv6, so I think it’s only fair that our certification programs start doing the same.  IPv6 should be integrated into every level of certification from CCNA/JNCIA all the way up to CCIE/JNCIE.

Tom’s Take

Working with IPv6 is a big change from the way we’ve done things in the past.  With SLAAC and integrated IPSec, the designers have done a great job of making our lives easier with things that we’ve needed for a long time.  However, we’re doing our best to preclude our transition to IPv6 by carrying over a lot of baggage from IPv4.  I know that our brains look for patterns and like to settle on familiarity as a way to help train for new challenges.  If we aren’t careful, we’re going to carry over too much of the old familiar networking and make IPv6 difficult to work with.  Unlearning what we think we know about networking is a good first step.  A person may learn something quickly with familiarity, but they can learn even faster when they approach it with a blank slate and a keen interest to learn.  With that approach, even the impossible won’t keep you from succeeding.