Link Local Address
Link Local
- Denoted by FE80 prefix
- Assign a single interface, multiple IPs
- Follow by the keyword "secondary"
- An OS in its default form, you are probably running IPv6, its on by default, in America you are less likely to not have IPv6 around.
- Link Local allows you to communicate with other devices, it is not use for routable communications, it is for a dedicated style of communications on our local subnet but not further.
- You could change the IP addresses and your routing won't change.
- Assign a single interface, multiple IPs
- Configured automatically in many devices
- EUI-64 supported but not required
- Built the address bits based on your mac-address, which will make it unique.
- The goal is to make a unique value, there is also a duplication check that we can do on the wire
- Unique value
- Locally (broadcast domain) significant
Link Local Example
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- Separate broadcast domains (right and left)
- You could have the same FE80 address as long as they are in different subnets (broadcast domains).
Duplicate addresses
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interface is noted with routing entries & neighbors to ensure proper delivery
Protocols That Leverage Link Local
- OSPFv3
- Provides capabilities for IPv6 addressing
- EIGRP
- Link local networks
- HSRP
- High Standard Routing Protocol
- RIP-NG
- Running on IPv6
EUI
- The host portion IPv6 addresses are created through a process called EUI-64
- Divide the MAC address in half
- Insert FFFE in between
- Invert the 7th bit
- E8-84-A5-32-28-45
- E8-84-A5 | 32-28-45
- E8-84-A5-FF-FE-32-28-45
- E8