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In this post we will try to configure IPv6 EIGRP see the different options for the protocol and how these options are almost identical to the IPv4 version of EIGRP configuration R1 ipv6 unicast-routing interface lo0 ipv6 address 2001:1:1::1/64 interface FastEthernet0/0   ipv6 address FE80::1 link-local   ipv6 address FC00:1:12::1/64 ! interface FastEthernet0/1   ipv6 address FE80::1 link-local   ipv6 address FC00:1:13::1/64 !          R2 ipv6 unicast-routing interface lo0 ipv6 address 2001:2:2::2/64 interface FastEthernet0/0   ipv6 address FE80::2 link-local   ipv6 address FC00:1:12::2/64 ! interface FastEthernet0/1   ipv6 address FE80::2 link-local   ipv6 address FC00:1:23::2/64 R3 ipv6 unicast-routing interface lo0 ipv6 address 2001:3:3::3/64 interface lo1 ipv6 address 2001:3:4::3/64 interface lo2 ipv6 address 2001:3:5::3/64 interface FastEthernet0/0   ipv6 address FE80::3 link-...

  In this post we will see how we can use the auto configuration options of IPv6 auto configuration feature built in IPv6 replaces many feature of IPv4 DHCP, although IPv6 DHCP still exists. with IPv6 auto configuration nodes can determine the Ipv6 prefixes on the link and the default router if required through ICMPv6 ND (Neighbor Discovery) In our setup we will have R1 configured with static IPv6 address and R2 will acquire its Ipv6 address automatically ipv6 unicast-routing has been enabled on both routers (config)#ipv6 unicast-routing   R1 configuration R1# sh run interf f0/0   ipv6 address FE80::1 link-local   ipv6 address 2001:12::1/64 R2 R2# sh run interf f0/0   ipv6 address FE80::2 link-local   ipv6 address auto-config that’s all on R2, so now let’s check R2 R2#show ipv6 interface f0/0 FastEthernet0/0 is up, line protocol is up     IPv6 is enabled, link-local address is FE80::2       No Vi...

IPv6 Unique Local Address ULA link local addresses are only significant on a single link link local addresses can overlap on the same router as long as defined on different interfaces starts with FE80::/10 link local addresses are mainly used by Ipv6 routing protocol, on broadcast networks link local addresses are automatically revolved through ICMP ND (ICMP Neighbor Discovery) since on non-broadcast this can’t be done this has to be manually mapping Link local addresses if not configured manually will be driven from the bia of the interface EUI Extended Unique Identifier  For example if the bia of an interface is as follows R2(config-if)#do sh interf f0/0 | in add   Hardware is Gt96k FE, address is c201.42b8.0000 (bia c201.42b8.0000) 1- FFEE is inserted after the vendor ID (most significant 3 bytes) C201.42FF.FEb8.0000 b- invert the 7th most significant bit, so  0x C2 is 1100 0010 binary invert the 1 to 0 , so this becomes 1100 0000 which is 0x C0 ...