![]() ![]() Note that I had noticed by default some Microsoft Operating Systems are not following the above method for auto generating the IPv6 Link Local addresses (for network security). The above IPv6 Link local address we got from combining FE80::/64 prefix and MAC Address part can be further simplified as FE80::C800:EFF:FE74:8. (Combining Link local IPv6 address prefix FE80:0000:0000:0000 with derived host part) Which means, if the 7th bit in the MAC address (from left) is 1, change it to 0 or if the 7th bit (from left) in the MAC address is 0, change it to 1. ![]() Also the 7th bit (from left) in the MAC address is flipped. ![]() The answer is, an hexadecimal number "FF:FE" is added in between the MAC address of the related interface to form the complete 128 bit IPv6 Link Local addresses. ![]() 64+48 is only 112bits to form IPv6 address (IPv6 addresses are 128 bit in length). The IPv6 Link Local addresses are made from the first 64-bit reservation (FE80::/64) and remaining bits are taken from the MAC address of the interface. Now we have the IPv6 Link local address of interface gigabitEthernet 0/0 as FE80::C800:EFF:FE74:8 and MAC address as ca00.0e74.0008. OmniSecuR1#show interfaces gigabitEthernet 0/0 The MAC address of interface gigabitEthernet 0/0 is ca00.0e74.0008. Next, view the interface information of the same interface mentioned above using the IOS command " show interfaces gigabitEthernet 0/0". How this IPv6 Link Local address as FE80::C800:EFF:FE74:8 is auto generated by the router? Read below. The output shows the IPv6 Link Local address as FE80::C800:EFF:FE74:8, for interface gigabitEthernet 0/0. Hosts use stateless autoconfig for addresses. ND advertised default router preference is Medium ND router advertisements live for 1800 seconds ND router advertisements are sent every 200 seconds ND advertised retransmit interval is 0 (unspecified) ND advertised reachable time is 0 (unspecified) ND reachable time is 30000 milliseconds (using 26049) ND DAD is enabled, number of DAD attempts: 1 ICMP error messages limited to one every 100 milliseconds IPv6 is enabled, link-local address is FE80::C800:EFF:FE74:8 GigabitEthernet0/0 is up, line protocol is up OmniSecuR1#show ipv6 interface gigabitEthernet 0/0 View the following output of show command "show ipv6 interface gigabitEthernet 0/0", in a Cisco router. IPv6 Link Local addresses are auto-generated and many international technology leaders generate IPv6 Link Local addresses from MAC Address of the interface. The scope of an IPv6 Link Local address is the local link. IPv6 Link Local addresses are used by devices for communicating with other nodes on the same link. A link-local address is for use on a single link and should never be routed. Typically, getting an APIPA IPv4 address in an IPv4 network is because of some network error, but a Link local addresses are IPv6 addresses which can be used for local communication. Link-local addresses are auto-configured (or auto-generated plug-and-play) addresses (Stateless addresses) similar to IPv4 APIPA addresses (169.254.0.0/16). Link-local addresses cannot be routed to public networks and limited to the local network. The IPv6 addresses starting with FE in hexadecimals represent link local IPv6 addresses. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |