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IPv6

IPv6 interface identifier

The second part of an IPv6 unicast or anycast address is typically a 64-bit interface identifier used to identify a host’s network interface. A 64-bit interface ID is created by inserting the hex value of FFFE in the middle of the MAC address of the network card. Also, the 7th Bit in the first byte is flipped to a binary 1 (if the 7th bit is set to 0 it means that the MAC address is a burned-in MAC address). When this is done, the interface ID is commonly called the modified extended unique identifier 64 (EUI-64).

For example, if the MAC address of a nework card is 00:BB:CC:DD:11:22 the interface ID would be 02BBCCFFFEDD1122.

Why is that so?
Well, first we need to flip the seventh bit from 0 to 1. MAC addresses are in hex format. The binary format of the MAC address looks like this:

hex 00BBCCDD1122
binary 0000 0000 1011 1011 1100 1100 1101 1101 0001 0001 0010 0010

We need to flip the seventh bit:

binary 0000 0010 1011 1011 1100 1100 1101 1101 0001 0001 0010 0010

Now we have this address in hex:

hex 02BBCCDD1122

Next we need to insert FFFE in the middle of the address listed above:

hex 02BBCCFFFEDD1122

So, the interface ID is now 02BB:CCFF:FEDD:1122.

Another example, this time with the MAC address of 00000C432A35.

1. Convert to binary and flip the seventh bit to one:

binary: 0000 0010 0000 0000 0000 1100 0100 0011 0010 1010 0011 0101

2. Convert back to hex:

hex: 02000C432A35

3. Insert FFFE in the middle:

interface ID: 02000CFFFE432A35

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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IPv6

IPv6 address prefixes

Here is a summary of the most common address prefixes in IPv6:

ipv6 prefixes

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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IPv6

IPv6 multicast addresses

Multicast addresses in IPv6 are similar to multicast addresses in IPv4. They are used to communicate with dynamic groupings of hosts, for example all routers on the link (one-to-many distribution).

Here is a graphical representation of the IPv6 multicast packet:

multicast ipv6 address

IPv6 multicast addresses start with FF00::/8. After the first 8 bits there are 4 bits which represent the flag fields that indicate the nature of specific multicast addresses. Next 4 bits indicate the scope of the IPv6 network for which the multicast traffic is intended. Routers use the scope field to determine whether multicast traffic can be forwarded. The remaining 112 bits of the address make up the multicast Group ID.

Some of the possible scope values are:

1 – interface-local
2 – link-local
4 – admin-local
5 – site-local
8 – organization-local
E – global

For example, the addresses that begin with FF02::/16 are multicast addresses intended to stay on the local link.

The following table lists of some of the most common link local multicast addresses:

commom link local multicast addresses ipv6

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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IPv6

Differences between IPv4 and IPv6

The following table summarizes the major differences between IPv4 and IPv6:

 

Feature IPv4 IPv6
Address length 32 bits 128 bits
Address representation 4 decimal numbers from 0-255 separated by periods 8 groups of  4 hexadecimal digits separated by colons
Address types unicast, multicast, broadcast unicast, multicast, anycast
Packet header 20 bytes long 40 bytes long, but simpler than IPv4 header
Configuration manual, DHCP manual, DHCP, auto-configuration
IPSec support optional built-in

 

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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IPv6

RIPng

RIPng is an extension of RIP developed for support of IPv6. Here are some of its features:

  • just like RIP for IPv4, it uses hop count as the metric
  • sends updates every 30 seconds
  • RIPng messages use the UDP port 521 and the multicast address of FF02::9

 

The configuration of RIPng is requires at least two steps:

1. enable RIPng using the global configuration command ipv6 router rip tag. The tag is used to differentiate between multiple RIP processes. It does not have to be the same on all routers in order to exchange routing information..
2. enable the routing protocol on the interface using the ipv6 rip tag enable. The tag has to match the one used in the ipv6 router rip tag command.

Here is an example:

ripng configuration

We have done a similar configuration on the second router. To verify that routers are indeed exchanging route information using RIPng we can use the show ipv6 route command:

show ipv6 route

In the picture above, we can see that the router has received a route to the network 2001:BBBB:CCCC:DDDD::/64.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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IPv6

IPv6 link-local addresses

Link-local IPv6 addresses have a smaller scope as to how far they can travel: only within a network segment that a host is connected to. Routers will not forward packets destined to a link-local address to other links. A link-local IPv6 address must be assigned to every network interface on which the IPv6 protocol is enabled. A host can automatically derive its own link local IP address or the address can be manually configured.

Link-local addresses have a prefix of FE80::/10. They are mostly used for auto-address configuration and neighbour discovery.

Here is a graphical representation of a link local IPv6 address:

Link local address

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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IPv6

IPv6 unique local addresses

Unique local IPv6 addresses have the similar function as IPv4 private addresses. They are not allocated by an address registry and are not meant to be routed outside their domain. Unique local IPv6 addresses begin with FD00::/8.

A unique local IPv6 address is constructed by appending a randomly generated 40-bit hexadecimal string to the FD00::/8 prefix. The subnet field and interface ID are created in the same way as with global IPv6 addresses.

A graphical representation of an unique local IPv6 address:

unique local ipv6 address

 

NOTE
The original IPv6 RFCs defined a private address class called site local. This class has been deprecated and replaced with unique local addresses.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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IPv6

IPv6 global unicast addresses

IPv6 global addresses are similar to IPv4 public addresses. As the name implies, they are routable on the internet. Currently IANA has assigned only 2000::/3 addresses to the global pool.

A global IPv6 address consists of two parts:

  • subnet ID – 64 bits long. Contains the site prefix (obtained from a Regional Internet Registry) and the subnet ID (subnets within the site).
  • interface ID – 64 bits long. typically composed of a part of the MAC address of the interface.

 

Here is a graphical representation of the two parts of an global IPv6 address:

global unicast ipv6 address

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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IPv6

How to configure IPv6

Cisco routers do not have IPv6 routing enabled by default. To configure IPv6 on a Cisco routers, you need to do two things:

  1. enable IPv6 routing on a Cisco router using the ipv6 unicast-routing global configuration command. This command globally enables IPv6 and must be the first command executed on the router.
  2. configure the IPv6 global unicast address on an interface using the ipv6 address address/prefix-length [eui-64] command. If you omit omit the eui-64 parameter, you will need to configure the entire address manually. After you enter this command, the link local address will be automatically derived.

 

Here is an IPv6 configuration example:

R1(config)#ipv6 unicast-routing
R1(config)#int Gi0/0
R1(config-if)#ipv6 address 2001:0BB9:AABB:1234::/64 eui-64

We can verify that the IPv6 address has been configured by using the show ipv6 interface Gi0/0 command:

R1#show ipv6 interface Gi0/0
GigabitEthernet0/0 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::201:42FF:FE65:3E01
  No Virtual link-local address(es):
  Global unicast address(es):
    2001:BB9:AABB:1234:201:42FF:FE65:3E01, subnet is 2001:BB9:AABB:1234::/64 [EUI]
  Joined group address(es):
    FF02::1
    FF02::2
    FF02::1:FF65:3E01
  MTU is 1500 bytes
  ....

From the output above we can verify two things:

  1. the link local IPv6 address has been automatically configured. Link local IP addresses begin with FE80::/10 and the interface ID is used for the rest of the address. Because the MAC address of the interface is 00:01:42:65:3E01, the calculated address is FE80::201:42FF:FE65:3E01.
  2. the global IPv6 address has been created using the modified EUI-64 method. Remember that IPv6 global addresses begin with 2000::/3. So in our case, the IPv6 global address is 2001:BB9:AABB:1234:201:42FF:FE65:3E01.

 

We will also create an IPv6 address on another router. This time we will enter the whole address:

R2(config-if)#ipv6 address 2001:0BB9:AABB:1234:1111:2222:3333:4444/64

Notice that the IPv6 address is in the same subnet as the one configured on R1 (2001:0BB9:AABB:1234/64). We can test the connectivity between the devices using ping for IPv6:

R1#ping ipv6 2001:0BB9:AABB:1234:1111:2222:3333:4444

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:0BB9:AABB:1234:1111:2222:3333:4444, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/0 ms

As you can see from the output above, the devices can communicate with each other.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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IPv6

IPv6 unicast addresses

Unicast addresses represent a single interface. Packets addressed to a unicast address will be delivered to a specific network interface.

There are three types of IPv6 unicast addresses:

  • global unicast – similar to IPv4 public IP addresses. These addresses are assigned by the IANA and used on public networks. They have a prefix of 2000::/3, (all the addresses that begin with binary 001).
  • unique local – similar to IPv4 private addresses. They are used in private networks and aren’t routable on the Internet. These addresses have a prefix of FD00::/8.
  • link local – these addresses are used for sending packets over the local subnet. Routers do not forward packets with this addresses to other subnets. IPv6 requires a link-local address to be assigned to every network interface on which the IPv6 protocol is enabled. These addresses have a prefix of FE80::/10.

 

Let’s describe each of the IPv6 unicast address type in more detail.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

Full Version 200-301 Dumps

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