Monday, July 23, 2012

ccnp route IPv6!!

Below lists some reserved and well-known IPv6 multicast address in the reserved multicast address range (FF00:: to FF0F::)

Multicast Address Multicast Group
FF01::1 All IPv6 nodes within the node-local scope
FF01::2 All IPv6 routers within the node-local scope
FF02::1 All IPv6 nodes within the link-local scope
FF02::2 All IPv6 routers within the link-local scope
FF02::5 All OSPFv3 routers within the link-local scope
FF02::6 All OSPFv3 designated routers within the link-local scope
FF02::9 All RIPng routers within the link-local scope
FF02::A All EIGRP routers within the link-local scope
FF02::D All PIM routers within the link-local scope
FF02::1:2 All DHCPv6 agents (servers and relays) within the link-local scope
FF05::2 All IPv6 routers within the site-local scope
FF02::1:FF00:0/104 IPv6 solicited-node multicast address within the link-local scope

Below is a summary of IPv6 transition technologies:
6 to 4 tunneling: This mechanism allows IPv6 sites to communicate with each other over the IPv4 network without explicit tunnel setup. The main advantage of this technology is that it requires no end-node reconfiguration and minimal router configuration but it is not intended as a permanent solution.

ISATAP tunneling (Intra-Site Automatic Tunnel Addressing Protocol): is a mechanism for transmitting IPv6 packets over the IPv4 network. The word “automatic” means that once an ISATAP server/router has been set up, only the clients must be configured to connect to it.

Teredo tunneling: This mechanism tunnels IPv6 datagrams within IPv4 UDP datagrams, allowing private IPv4 address and IPv4 NAT traversal to be used.

In fact, GRE tunneling is also an IPv6 transition mechanism but is not mentioned in ROUTE so we shouldn’t choose it (there are 4 types of IPv6 transition mechanisms mentioned in ROUTE; they are: manual, 6-to-4, Teredo and ISATAP).

The metric of a summary route is the highest cost of the routes being summarized.

6to4 tunnels use IPv6 addresses that concatenate 2002::/16 with the 32-bit IPv4 address of the edge router, creating a 48-bit prefix.

OSPFv3 for IPv6 authentication is supported by IPv6 IPsec. 

The automatic configuration is a great feature of IPv6. Imagine you have to manually configure an IPv6 address with 128-bit long, what a pain! With this feature, it is no longer necessary to configure each host manually. But notice that host only autonomously configures its own Link-local address (the IP address used on a LAN). The Link-local address can be created automatically using a link-local prefix of FE80::/10 and a 64-bit interface identifier (based on 48-bit MAC address).

For example, if your MAC address is 00:12:34:56:78:9a, your 64-bit interface identifier is 0012:34FF:FE56:789a (16-bit FFFE is inserted in the middle). And notice that the notation has been changed because IPv6 addresses require 16-bit pieces to be separated by “:”.

Then, according to the RFC 3513 we need to invert the Universal/Local bit (“U/L” bit) in the 6th position of the first octet (start counting from 0). The “u” bit is set to 1 to indicate Universal, and it is set to zero (0) to indicate local scope. In this case, we set this bit to 1 because the MAC address is universally unique. Thus the result is: 0212:34FF:FE56:789a.

Finally, add the link-local prefix FE80 to create the full IPv6 address: FE80:0:0:0:0212:34FF:FE56:789a (or FE80::212:34FF:FE56:789a, in short form).

Note: The reason for inverting the “U/L” bit is to allow ignoring it for short values in the manual configuration case. For example, you can manually assign the short address fc80::1 instead of the long fc80:0:0:0:0200::1.

When a client sends a Router Solicitation (RS) message, router responds with a Router Advertisement (RA) message which includes prefix, default route and lifetime (how long the host should retain information about the router)

IPv6 router solicitation is a request made by a node for the IP address of the local router.

Each host can auto-configure its address without the aid of a DHCP server.

The command “clear ipv6 ospf” will clear the present routing table and force the OSPFv3 process to build a new one. This command is often used when something in the network was changed or for debugging purpose.

The command “ipv6 router ospf process-id” is used to enable an OSPF process on the router. For example:
Router(config)#ipv6 router ospf 1
Note: This command is used in global configuration mode.

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