IPv6 Network Discovery

Author
Terry Slattery
Principal Architect

I recently received a comment from Gerry Gerofsky about IPv6 network discovery:

Hi Terry,    I am trying to understand how CiscoWorks, OpenView discovers an IPv6 network?    In Ipv4, typically a tool like OpenView CiscoWorks, you  feed it a subnet and it goes and checks all the IP’s.    What is available in IPv6?  In this case, given 2^64 hosts  in a subnet, the same sort of scan does not sound logical.  This will be a great topic, and I have spent the past day trying to find an answer without avail.  Thanks a lot  Cheers,  Gerry

As you’ve noted, network discovery in IPv6 doesn’t work by using ping sweeps because the address space is simply too large.  The key is to identify which devices are likely to know about all or most of its neighbors, such as the default router on the subnet.  I’ve mentioned before that it is a good idea to give each default router (and all network infrastructure devices in a subnet) an address out of a well-known range of addresses, such as ::1.  Network discovery would query this device (via SNMP or CLI or other management mechanism) to query its IPv6 neighbor table, thus finding all the IPv6 neighbors on that subnet.

But what about doing a full network discovery?  By starting with a seed router, and learning the IPv6 addresses of routing neighbors, one could build a table of all the routers in the infrastructure and the subnets that they service.  Then query each router’s IPv6 neighbor table to learn of the IPv6 devices on each subnet.

Another mechanism, which may provide some additional information, is to use a probe to capture flow data, such as source/destination address information as it crosses a key point in the infrastructure.  This typically gives you address information about hosts and may be useful in learning of new subnets.

To help with management of the infrastructure, I’d enable CDP/LLDP on all internal interfaces (disable it on externally facing interfaces), so that neighboring infrastructure devices can be more easily discovered.  I recommend this for IPv4 as well.  While not strictly necessary, it helps speed up the infrastructure discovery process.

-Terry

_____________________________________________________________________________________________

Re-posted with Permission 

NetCraftsmen would like to acknowledge Infoblox for their permission to re-post this article which originally appeared in the Applied Infrastructure blog under http://www.infoblox.com/en/communities/blogs.html

infoblox-logo

Leave a Reply

 

Nick Kelly

Cybersecurity Engineer, Cisco

Nick has over 20 years of experience in Security Operations and Security Sales. He is an avid student of cybersecurity and regularly engages with the Infosec community at events like BSides, RVASec, Derbycon and more. The son of an FBI forensics director, Nick holds a B.S. in Criminal Justice and is one of Cisco’s Fire Jumper Elite members. When he’s not working, he writes cyberpunk and punches aliens on his Playstation.

 

Virgilio “BONG” dela Cruz Jr.

CCDP, CCNA V, CCNP, Cisco IPS Express Security for AM/EE
Field Solutions Architect, Tech Data

Virgilio “Bong” has sixteen years of professional experience in IT industry from academe, technical and customer support, pre-sales, post sales, project management, training and enablement. He has worked in Cisco Technical Assistance Center (TAC) as a member of the WAN and LAN Switching team. Bong now works for Tech Data as the Field Solutions Architect with a focus on Cisco Security and holds a few Cisco certifications including Fire Jumper Elite.

 

John Cavanaugh

CCIE #1066, CCDE #20070002, CCAr
Chief Technology Officer, Practice Lead Security Services, NetCraftsmen

John is our CTO and the practice lead for a talented team of consultants focused on designing and delivering scalable and secure infrastructure solutions to customers across multiple industry verticals and technologies. Previously he has held several positions including Executive Director/Chief Architect for Global Network Services at JPMorgan Chase. In that capacity, he led a team managing network architecture and services.  Prior to his role at JPMorgan Chase, John was a Distinguished Engineer at Cisco working across a number of verticals including Higher Education, Finance, Retail, Government, and Health Care.

He is an expert in working with groups to identify business needs, and align technology strategies to enable business strategies, building in agility and scalability to allow for future changes. John is experienced in the architecture and design of highly available, secure, network infrastructure and data centers, and has worked on projects worldwide. He has worked in both the business and regulatory environments for the design and deployment of complex IT infrastructures.