New IPv6 Features in Cisco IOS 15.0

A few new IPv6 features in Cisco’s latest software

You may have heard that Cisco has released IOS version 15.0. This new IOS version has many new advancements. However, it only has a few new IPv6 features for multicast and OSPFv3. Based on the IPv6 features that have come out in IOS 12.4T we should expect many new IPv6 features in IOS 15.0M and IOS 15.0T in the coming years.

Like you, I always like keeping up on the latest technology. One of the things that I enjoy about the computer networking industry is that there are always new things to learn and share. The advancements in the industry come in the form of both hardware and software. When it comes to software, I always want to learn about the latest Cisco IOS features. While these features won't likely be implemented in production networks right away, seeing these new IOS features helps us plan for our future networks.

I started my career learning about Cisco IOS version 9.11 back in 1994. In 1995 I took my first Cisco class called Introduction to Cisco Router Configuration (ICRC) on IOS 10.3. Back then the entire documentation for IOS was only a few small books. The size of the documentation grew quickly with the size of the IOS firmware image. I had a complete set of IOS 11.2 documentation back when I was studying for my CCIE lab. It filled up an entire shelf of my bookcase. It was during the transition from 11.3 to 12.0 that Cisco stopped printing the entire IOS documentation set. That seems like a long time ago because it was. Now the IOS documentation set can barely fit onto a DVD.

Cisco has just released IOS 15.0. Don't ask me why Cisco jumped from 12 to 15. Maybe it has something to do with 13 being considered an unlucky number and the fact that in many buildings that don't have a 13th floor the 14th floor is really just the 13th floor. Cisco must have Triskaidekaphobia. To avoid all those sticky issues, Cisco probably decided to jump clear to 15 (which still is the next release following 12 but not to be confused with the 13th version).

I haven't been able to download the IOS yet for the routers in my lab but hopefully that is coming soon. However, the documentation for Cisco IOS release 15.0 is already available so we can start to see what to expect.

You can learn about how to configure the latest IPv6 features by perusing the IOS 15.0 "IPv6 configuration guide". All of the latest IPv6 commands can be found in the IOS 15.0 "IPv6 Command Reference". There is also a document that covers the "New Features in Cisco IOS Release 15.0(1)M".

In IOS release 15.0 there are three new IPv6 features.

IPv6: Multicast Address Group Range Support

OSPFv3 Fast Convergence-LSA and SPF Throttling

OSPFv3 Graceful Restart

New software is never without its bugs. I find it useful to go through the release notes and caveats for new IOS versions I am planning on deploying to make sure I am not going to run into a problem that someone has already encountered. In IOS 15.0 there are several caveats that you should know about. One serious problem when doing "debug ipv6 inspect" may cause the router to crash. There are a couple of NAT-PT bugs - try to avoid NAT-PT if at all possible. One GLBP for IPv6 bug seems pretty bad and there is a MBGP bug with IPv6 link local addresses.

These few new IPv6 features in IOS 15 are only a few of what we should expect in IOS 15. The track record of IPv6 features that have been coming out in 12.4T show that Cisco is putting significant effort into IPv6 development. Just look at the large number of IPv6 features that came out in 12.4(20)T. Below is a list I have been compiling of the IPv6 features in IOS 12.4T.


  • IPv6 ACL Extensions for Mobile IPv6
  • IPv6 BSR-Ability to Configure RP Mapping
  • IPv6 Default Router Preference
  • IPv6 Source Specific Multicast (SSM) Mapping


  • IPv6 IPsec Router-to-Router Tunnels
  • SYSLOG over IPv6


  • IPv6 IPSec on VAM2+
  • Configuring EIGRP for IPv6
  • GLBP Support for IPv6
  • IPv6 Switching Provider Edge Router over MPLS (6PE)
  • HSRP Support for IPv6


  • OSPF IPv6 (OSPFv3) IPSec ESP Encryption and Authentication


  • Mobile IPv6 Authentication Option Support
  • Mobile IPv6 Network Access Identifier (NAI) Support


  • DHCPv6 Stateless Enhancements


  • Flexible NetFlow - IPv6 Unicast Flows - Removal of IPv6 NetFlow
  • IPv6-CNS Agents
  • IPv6-Config Logger
  • IPv6-HTTP(S)
  • IPv6-IP SLAs (UDP Jitter, UDP Echo, ICMP Echo, TCP Connect)
  • IPv6-Netconf
  • IPv6-SOAP
  • IPv6-TCL
  • IPv6 ACL Extensions for IPsec Authentication Header
  • IPv6 over DMVPN
  • IPv6 VPN over MPLS (6VPE)
  • MPLS VPN-VRF CLI for IPv4 & IPv6 VPNs
  • Mobile IP-Mobile IPv6 HA Phase 2 - NEMO


  • IPv6 Boot Strap Router (BSR)
  • IPv6 Source Specific Multicast (SSM) Mapping
  • IPv6 ACL Extensions for Mobile IPv6
  • IPv6 Default Router Preference


  • Secure Neighbor Discovery (SeND)
  • DHCPv6 Individual Address Assignment

Hopefully Cisco will continue its development of IPv6 and we can expect even more features in coming releases of IOS 15.


Join the Network World communities on Facebook and LinkedIn to comment on topics that are top of mind.

Copyright © 2009 IDG Communications, Inc.

IT Salary Survey: The results are in