Fredrik Holmberg

Network Consultant  

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IPv6 Autoconfiguration with SLAAC and NDP, how does it work?

Unlike the prehistoric IPv4 protocol which relies on DHCP servers to be able to communicate and do anything useful, the modern IPv6 protocol is much more self-sufficient and in tune with 2012.

Introducing IPv6 Stateless Address Autoconfiguration or SLAAC. Described in RFC 4862 SLAAC is a mechanism that:

“requires no manual configuration of hosts, minimal (if any) configuration of routers, and no additional servers. The stateless mechanism allows a host to generate its own addresses using a combination of locally available information and information advertised by routers”

In Apple terms; it’s like magic!

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Configuring Single-Area OSPFv3

Configuring OSPFv3 is not very different from configuring OSPF for IPv4. It’s actually simpler and much cooler since it’s running on IPv6.

Either prepare a topology using GNSparser or use this one:

single_area_ospfv3

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Dynamic Multipoint IPv6 tunnels using 6to4

6to4 is a transition mechanism that allows modern IPv6 sites to communicate over a legacy IPv4 network, like The Internet. Just like other auto-tunneling techniques the IPv6 end-to-end connectivity is made possible by encapsulating the IPv6 datagrams inside IPv4 datagrams.

Auto-tunneling is a last resort method compared to dual-stack or native IPv6 support, but it can be used as a temporary solution for providing IPv6 connectivity. Just don’t expect kick-ass performance http://www.potaroo.net/ispcol/2010-12/6to4fail.html.

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Another way of doing IPv4 subnetting

There are many ways to understand subnetting. Here is a method that I use to figure out the IPv4 network address, the first address and the last broadcast address quite easily.

The following part requires understanding of the basic concepts of subnetting and binary math.

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Generating loopback interfaces using Tcl

When doing networking labs you often need to configure a series of loopback interfaces to simulate connected subnets and so on. Configuring them manually on every router or using Notepad with search and replace can be a pain. Here’s another way to do it!

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