Jeremy Stretch has generously contributed a few of his great articles into the CT3 wiki: the Policing versus Shaping article describes the performance impact both QoS mechanisms have on TCP sessions and the IPv6 EUI-64 article describes the algorithm that's used to transform a MAC address into an IPv6 address, resulting in automatic generation of unique IPv6 interface addresses.
If you want to display any IPV6-related BGP objects (neighbors, routes …) you can use the familiar BGP commands, but have to prefix them with show ip bgp ipv6 unicast. For example, to display the BGP neighbors active in the IPv6 address family, you would use show ip bgp ipv6 unicast summary command. I doubt you like so much typing (I don't, just entering the IPv6 addresses is enough for me); luckily Cisco IOS has aliases - just configure alias exec bgpv6 show ip bgp ipv6 unicast and (for consistency) alias exec bgpv4 show ip bgp ipv4 unicast.With these aliases, the BGP IPv6 maintenance and troubleshooting becomes almost enjoyable:
PE-C#bgpv6 summary ¦ begin Neighbor
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.0.1.1 4 65000 18 21 11 0 0 00:12:49 2
10.0.1.2 4 65000 20 20 11 0 0 00:12:50 2
FEC0:C0FF:EE00::11:2
4 65100 984 1086 11 0 0 16:16:33 2
PE-C#bgpv6 regexp 65100
BGP table version is 11, local router ID is 10.0.1.5
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> FEC0::1:3/128 FEC0:C0FF:EE00::11:2
0 0 65100 i
*> FEC0:1:0:3::/64 FEC0:C0FF:EE00::11:2
0 0 65100 i
If you want to understand the buzz raised recently about IP version 6, and your daily job includes more budget meetings, payroll discussions or strategy/operational planning than router configuration, Global IPv6 Strategies: From Business Analysis to Operational Planning (Cisco Press, 2008) is a mandatory book for you.
The brief display of the state of IPv6 interfaces in the router (show ipv6 interface brief) is significantly different from the well-known show ip interface brief display as the IPv6 address might not fit in the same line as all the other data. To filter the printout and display only the operational interfaces, you have to replace the include filter with the section filter, which displays all the lines matching the regular expression as well as associated follow-up lines.
PE-A#show ipv6 interface brief | section up
Serial1/0 [up/up]
unassigned
Serial1/1 [up/up]
FE80::C800:CFF:FEA7:0
Loopback0 [up/up]
unassigned
The definition of the associated follow-up lines depends on the printout. Usually the indented lines are assumed to belong to a section, but you might be surprised.
One of the obscure facts of IPv6 OSPF (OSPFv3) is that it uses a 32-bit router ID like OSPFv2. It's a reasonable choice, I haven't seen an OSPF network with more than a billion routers yet. However, could you guess how this requirement is implemented in Cisco IOS? OSPFv3 searches for an IPv4 address (effectively the same algorithm used by OSPFv2) to get the router ID for the IPv6 routing process. Neat, isn't it?
You might wonder what happens if you want to configure an IPv6-only router. OSPF won't start unless you configure the router ID manually. And, no, you cannot enter a number (which would be the expected format, as the router ID is just a number in the IPv6 world), you have to enter an IPv4 address. Long live IPv4 :))Here is a sample printout from a router. First, let's check the interface status:
Site-D(config)#do show ip interface briefNo IPv4 running anywhere. Good. Let's continue and configure IPv6:
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES manual up up
FastEthernet0/1 unassigned YES manual up up
Loopback0 unassigned YES manual up up
Site-D(config)#ipv6 unicastOops, IPv6 OSPF won't start if the router doesn't have an IPv4 address. Let's configure the router ID:
Site-D(config)#ipv6 router ospf 1
Site-D(config-rtr)#
*Mar 1 01:18:46.423: %OSPFv3-4-NORTRID: OSPFv3 process 1 could not pick a router-id,
please configure manually
Site-D(config-rtr)#router-id ?
A.B.C.D OSPF router-id in IP address format
Site-D(config-rtr)#router-id 10.0.1.8
Site-D(config-rtr)#
If you're a Cisco partner, you can run the Configuring OSPFv3 remote lab exercise free-of-charge from Partner Education Connection. Everyone else can get the same exercise as part of the IPv6 remote lab bundle from our learning store, where you can also buy the IPv6 Fundamentals, Design and Deployment (IP6FD) e-course.
In response to my January IP Corner article The Never-Ending Story of IP Fragmentation, Stojanco Cavdarov made an interesting observation: routers are not allowed to fragment IPv6 packets, they have to respond back with ICMP unreachable (effectively, routers behave as if IPv6 packets would have an implicit don't fragment bit).
To make life easier for non-TCP IPv6 applications (TCP is supposed to use Path MTU Discovery), the minimum IPv6 packet size that has to be supported on all links was increased to 1280 bytes (which, incidentally, fits very nicely into GRE+IPSec envelope transported across links with 1500-byte MTU).
Do you want to gain IPv6 configuration skills and test the associated routing protocols at the time that suits you most? The IPv6 e-course allows you to do just that.
The IPv6 Fundamentals, Design and Deployment (IP6FD) e-course is a blended learning solution that consists of the IP6FD web-based training and associated remote lab bundle. The course provides you with knowledge and skills needed for transitioning to IPv6 based networks. The content encompasses design and security considerations, IPv6 configuration principles and IPv6 transition mechanisms. You will learn how to implement IPv6 in a network using numerous routing protocols such as RIP, EIGRP, OSPF, IS-IS and BGP, as well as hands-on skills in deploying IPv6 transition mechanisms including various types of tunnels.
You can find additional e-courses in our catalog.
If you need to improve your hands-on IPv6 skills and have access to Cisco's Partner Education Connection, you can get a number of IPv6 remote lab exercises free-of-charge.
Everyone else can buy the same labs from our learning store. For example, for €128, you can get a one week unlimited access to the labs with the ability to repeat every exercise as ofter as you need.
To view the PEC lab content and schedule the labs, just click on one of the following links:
A while ago I was asked to write an article about IPv6 training. I could just cover the training aspect, like what's offered (answer: not much) and whether someone can train the whole operations team like you could in the IPv4 or MPLS/VPN world (answer: no), but I wanted to understand whether anyone is really using IPv6 in a production network. I found a few academic networks (after all, there are about 2000 IPv6 prefixes assigned and someone should be doing something with them), but not much of what I would call a real production environment, which is a bad thing, as it looks like the IPv4 address space will get saturated in a few years.
My conclusions are summarized in the article I wrote for SearchTelecom.com. I still have mixed feelings about our ability to be IPv6-ready when needed (as well as when we'll need it). At the very least, if you're running an enterprise network, there's no need to rush (unless, of course, there are tax breaks or incentives on the horizon); unless you decide to deploy IPv6 internally (hopefully for a good reason), the first time you'll meet it is when you'll deploy dual stack on your public servers to avoid NATing to IPv6-only clients on the public Internet.
Of course, I can be completely wrong, in which case I would highly appreciate your corrections.
In one of his recent articles, Scott Morris provided an excellent summary why IPv6 is still on the horizon. The point I like most (as it's often forgotten by the techies) is this:
“After all of the pieces (network, applications, OS, etc.) are done, do you have enough people with enough knowledge to manage and design things? Now may be a good time for some training!”
Cisco has already included IPv6 in its mainstream BSCI course (so IPv6 is now officially part of CCNP certification). Apart from visiting the BSCI classroom course, you also have a few other options to get your hands on IPv6 training material:
