IPv6: Multicast address, global unicast (link local scope), link local address and Static route configuration.

I have difficulty getting used to IPv6, however sooner or later the world of the internet will adopt this change so I would get used to it and practise and practise and more practise.

For the addressing I am using a global unicast address which is 2xxx/4 or 3xxx/4.

For global unicast, the first 3 upper bits are 001, making the address either starts with a 2xxx (0010) or 3xxx (0011), the prefix /4 means the first 4 bits such as 0010 is unchanged hence making 2xxx/4, and the first 4 bits 0011 is unchanged hence 3xxx/4

Loopback: ::1/128 meaning the entire ipv6 128 bit is 0000:0000:0000:0000:0000:0000:0000:0001 and is unchanged. Because leading zeroes can be abbreviated into double colons hence the short-hand presentation is ::1/128.

Multicast address has first 8 bits set to 1 like this 1111:1111 hence FF in hexadecimal representation. FF00::/8 reserved for multicast, the first 8 bits must FF the remaining 120 bits can be changed, for this reason if you see FFxxx you know it belongs to multicast example: FF02::1 means multicast to all, similar to ipv4 224.0.0.1

I made this table to compare between IPv4 MC address and IPv6 MC address of different routing protocols. I did not specify the protocol versions.

For global unicast address, the full addressing space is divided as follows:

1. first 48-bits are network-prefix to identify the network id, this is for routing.

2. the next 16-bit belongs to subnet-id, total subnets available is 2^16 = 65536

3. the remaining 64-bit belongs to interface id, for host identification.

The following is an excerpt from Routing TCP/IP volume 1, page 54:

Local internet registries might assign prefix of a different length:

1. If the customer pool is very large, a prefix shorter than /48 might be assigned.

2. If one and only one subnet is to be addressed, a /64 might be assigned.

3. If one and only one device is to be addressed, a /128 might be assigned.

In order to understand better I started off with static route using IPv6..

Important: Try to get at least an advanced ip services image to do ipv6 lab, the cisco1841 router which I bought came with ip base image pre-installed which cannot do ipv6 addressing as well as ipv6 routing.

Because ipv6 routing is not widely deployed as of year 2010, in order to preserve router’s memory cisco decided to turn off ipv6 unicast-routing by default. Before you start doing ipv6 routing remember to turn on ipv6 unicast-routing command.

2651-1(config)#ipv6 unicast-routing

Turn on this ipv6 routing for all routers in case I have forgotten.

2651-2(config)#ipv6 unicast-routing
2651-2(config)#
Tserver#3
[Resuming connection 3 to 2651-3 … ]

2651-3(config)#ipv6 unicast-routing
2651-3(config)#
Tserver#4
[Resuming connection 4 to 2651-4 … ]

2651-4(config)#ipv6 unicast-routing
2651-4(config)#

You can copy and paste these lines if you wish, I recommend do not copy and paste, get familiar through iteration.

2651-1#sh run | section int
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address 2001:11AA::1/64

2651-2#sh run | section inter
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address 2001:11AA::2/64
interface FastEthernet0/1
no ip address
duplex auto
speed auto
ipv6 address 2001:22AA::2/64

2651-3#sh run | section int
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address 2001:33AA::3/64
interface FastEthernet0/1
no ip address
duplex auto
speed auto
ipv6 address 2001:22AA::3/64

2651-4#sh run | section int
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address 2001:33AA::4/64

After you have configured the ipv6 addresses, we can proceed to do static route. Before you do the static route ensure you can ping within the same subnet.

2651-1#ping ipv6 2001:11aa::2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:11AA::2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/2/4 ms

The following configurations are ipv6 static route configuration:

2651-1#sh run | s ipv6 route
ipv6 route 2001:22AA::/64 2001:11AA::2
ipv6 route 2001:33AA::/64 2001:11AA::2

2651-2#sh run | s ipv6 route
ipv6 route 2001:33AA::/64 2001:22AA::3

2651-3#sh run | s ipv6 route
ipv6 route 2001:11AA::/64 2001:22AA::2

2651-4#sh run | s ipv6 route
ipv6 route 2001:11AA::/64 2001:33AA::3
ipv6 route 2001:22AA::/64 2001:33AA::3

show ipv6 route command shows the ipv6 routing table:

2651-1#sh ipv6 route
IPv6 Routing Table – 6 entries
Codes: C – Connected, L – Local, S – Static, R – RIP, B – BGP
U – Per-user Static route
I1 – ISIS L1, I2 – ISIS L2, IA – ISIS interarea, IS – ISIS summary
O – OSPF intra, OI – OSPF inter, OE1 – OSPF ext 1, OE2 – OSPF ext 2
ON1 – OSPF NSSA ext 1, ON2 – OSPF NSSA ext 2
C   2001:11AA::/64 [0/0]
via ::, FastEthernet0/0
L   2001:11AA::1/128 [0/0]
via ::, FastEthernet0/0
S   2001:22AA::/64 [1/0]
via 2001:11AA::2
S   2001:33AA::/64 [1/0]
via 2001:11AA::2
L   FE80::/10 [0/0]
via ::, Null0
L   FF00::/8 [0/0]
via ::, Null0

L stands for local, FF00::/8 belongs to multicast, FE80::/10 belongs to link local address, L   2001:11AA::1/128 [0/0] this is the local unicast addressing to only 2651-1 fastEthernet 0/0 interface.

Verification using ICMPv6:

2651-1#ping ipv6 2001:33aa::4

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:33AA::4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms

2651-4#ping ipv6 2001:11aa::1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:11AA::1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms

End to end can ping the rest should not be a problem. One funny thing, without the keyword ipv6 there’s still echo reply!

2651-4#ping 2001:11aa::1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:11AA::1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms

2651-1#ping 2001:22aa::3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:22AA::3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/2/4 ms

2651-1#sh ipv6 neighbors
IPv6 Address                              Age Link-layer Addr State Interface
FE80::213:1AFF:FEDE:F420                    1 0013.1ade.f420  STALE Fa0/0
2001:11AA::2                                0 0013.1ade.f420  STALE Fa0/0

FE80::213:1AFF:FEDE:F420 link local address of 2651-2 fa0/0!

From Routing TCP/IP Volume 2 page 682:

STALE: An entry in the neighbor cache has not been verified as reachable within 30 seconds. blah blah blah, no action is required until traffic is sent to the STALE entry

2651-1#ping ipv6 2001:11aa::2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:11AA::2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/1/4 ms
2651-1#sh ipv6 neigh
2651-1#sh ipv6 neighbors
IPv6 Address                              Age Link-layer Addr State Interface
FE80::213:1AFF:FEDE:F420                    5 0013.1ade.f420  DELAY Fa0/0
2001:11AA::2                                0 0013.1ade.f420  REACH Fa0/0

After I sent a ping to the global unicast link local scope address 2001:11aa::2, the state becomes REACH, which means reachable.

Look at the link local is delay, refer to page 682:

DELAY: No reachable verification has been received within the past 30 seconds, and  a packet has been sent to specified neighbour within the past 5 seconds.

Based on this statement, I sent a packet to the global unicast link local scope address, but has not sent reachable ping to the link local address.

To ping link local address I need to specify the output interface name IN FULL.

2651-1#ping fe80::213:1aff:fede:f420
Output Interface:
% Interface required
2651-1#ping fe80::213:1aff:fede:f420
Output Interface: fa0/0
% Invalid interface. Use full interface name without spaces (e.g. Serial0/1)
Output Interface: fastEthernet0/0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to FE80::213:1AFF:FEDE:F420, timeout is 2 seconds:
Packet sent with a source address of FE80::213:60FF:FE01:C7E0
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/2/4 ms

From the output FE80::213:60FF:FE01:C7E0 is the link local address of 2651-1 fa0/0 interface.

2651-1#sh ipv6 neighbors
IPv6 Address                              Age Link-layer Addr State Interface
FE80::213:1AFF:FEDE:F420                    0 0013.1ade.f420  REACH Fa0/0
2001:11AA::2                                7 0013.1ade.f420  STALE Fa0/0

Advertisements
This entry was posted in IPv6 and tagged . Bookmark the permalink.

2 Responses to IPv6: Multicast address, global unicast (link local scope), link local address and Static route configuration.

  1. Pingback: Online Beat Maker Machine

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s