We will use the same topology as in the IPv6 addressing lesson, but we will add one more router to demonstrate the capabilities of the routing protocols.

We have added R3 to our topology. R3’s FastEthernet0/0 interface is connected to R2’s FastEthernet0/1 interface. If correctly configured these interfaces, we will be have IPv6 connectivity, but we will not be able to reach the other routers from R3. Let’s start by configuring R2’s Fa0/1 interface and R3. For the rest of the configuration, please refer to the IPv6 Address Configuration lesson.

R2#conf t
R2(config)#interface Fa0/1
R2(config-if)#ipv6 address 2001:db8:1:3::/64 eui-64
R2(config-if)#no shutdown

R3#conf t
R3(config)#ipv6 unicast-routing
R3(config)#interface Fa0/0
R3(config-if)#ipv6 address 2001:db8:1:3::/64 eui-64
R3(config-if)#no shutdown

Let’s now check the IPv6 interface configuration.

R2#show ipv6 interface brief
FastEthernet0/0            [up/up]
FE80::C60B:EFF:FED4:0
2001:DB8:1:2:C60B:EFF:FED4:0
FastEthernet0/1            [up/up]
FE80::C60B:EFF:FED4:1
2001:DB8:1:3:C60B:EFF:FED4:1

R3#show ipv6 interface brief
FastEthernet0/0            [up/up]
FE80::C60D:EFF:FED4:0
2001:DB8:1:3:C60D:EFF:FED4:0
FastEthernet0/1            [administratively down/down]

It looks like the configuration of the interfaces was successful. Let’s now try to test end-to-end connectivity by using the ping command.

R3#ping 2001:DB8:1:3:C60B:EFF:FED4:1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:1:3:C60B:EFF:FED4:1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 24/84/204 ms

R2#ping 2001:DB8:1:3:C60D:EFF:FED4:0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:1:3:C60D:EFF:FED4:0, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/72/100 ms

We are now sure that we have connectivity between those two routers. But what happens if we want to ping R0 from R3? Yes, you will get timeouts, because the R2 does not know how to forward packets to R0. In order to get connectivity between all of our routers, we must use either static routing or a dynamic routing protocol.

The CCNA exam, requires the candidate to be able to configure RIPng. RIPng is the RIP version for IPv6 networks. The RIPng configuration is very easy. All you have to do after you have correctly configured the IPv6 addresses on the interfaces of your routers, is to start a RIPng process, and enable it on the desired interfaces. The general commands for this are the ipv6 router rip process-name global configuration command and the ipv6 rip process-name enable interface configuration command.

We will call our RIPng process RT0 in our examples. The name does not have to be the same, it’s importance is only locally.

R0#conf t
R0(config)#ipv6 router rip RT0
R0(config-rtr)#interface FastEthernet0/0
R0(config-if)#ipv6 rip RT0 enable
R0(config-if)#interface FastEthernet0/1
R0(config-if)#ipv6 rip RT0 enable

R1#conf t
R1(config)#ipv6 router rip RT0
R1(config-rtr)#interface Fa0/0
R1(config-if)#ipv6 rip RT0 enable

R2#conf t
R2(config)#ipv6 router rip RT0
R2(config-rtr)#interface Fa0/0
R2(config-if)#ipv6 rip RT0 enable
R2(config-if)#interface Fa0/1
R2(config-if)#ipv6 rip RT0 enable

R3#conf t
R3(config)#ipv6 router rip RT0
R3(config-rtr)#interface Fa0/0
R3(config-if)#ipv6 rip RT0 enable

Now let’s check how the routing table looks like on R3.

R3#show ipv6 route
IPv6 Routing Table – 5 entries
Codes: C – Connected, L – Local, S – Static, R – RIP, B – BGP
U – Per-user Static route, M – MIPv6
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
D – EIGRP, EX – EIGRP external
R   2001:DB8:1:1::/64 [120/3]
via FE80::C60B:EFF:FED4:1, FastEthernet0/0
R   2001:DB8:1:2::/64 [120/2]
via FE80::C60B:EFF:FED4:1, FastEthernet0/0
C   2001:DB8:1:3::/64 [0/0]
via ::, FastEthernet0/0
L   2001:DB8:1:3:C60D:EFF:FED4:0/128 [0/0]
via ::, FastEthernet0/0
L   FF00::/8 [0/0]
via ::, Null0

As you can see, the routes learned through RIP are preceded by R. Our routers know now how to reach any other router from the network.

In your troubleshooting process, you can also check who are the neighbors of your router:

R2#show ipv6 neighbors
IPv6 Address                              Age Link-layer Addr State Interface
2001:DB8:1:3:C60D:EFF:FED4:0                0 c40d.0ed4.0000  REACH Fa0/1
FE80::C609:EFF:FED4:1                       0 c409.0ed4.0001  REACH Fa0/0

If you want to check the routing protocols used in IPv6, you can do it with show ipv6 protocols.

R0#show ipv6 protocols
IPv6 Routing Protocol is “connected”
IPv6 Routing Protocol is “static”
IPv6 Routing Protocol is “rip RT0”
Interfaces:
FastEthernet0/1
FastEthernet0/0
Redistribution:
None

We can see here that IPv6 routing is functioning for the connected networks as well as for the configured static routes. In addition to that, RIP is also functioning with the process name RT0.

More detailed information about RIP can be found with the show ipv6 rip command.

R0#show ipv6 rip
RIP process “RT0″, port 521, multicast-group FF02::9, pid 245
Administrative distance is 120. Maximum paths is 16
Updates every 30 seconds, expire after 180
Holddown lasts 0 seconds, garbage collect after 120
Split horizon is on; poison reverse is off
Default routes are not generated
Periodic updates 150, trigger updates 3
Interfaces:
FastEthernet0/1
FastEthernet0/0
Redistribution:
None

You can also check how much IPv6 traffic is passing your router with show ipv6 traffic.

R0#show ipv6 traffic
IPv6 statistics:
Rcvd:  541 total, 531 local destination
0 source-routed, 0 truncated
0 format errors, 0 hop count exceeded
0 bad header, 0 unknown option, 0 bad source
0 unknown protocol, 0 not a router
0 fragments, 0 total reassembled
0 reassembly timeouts, 0 reassembly failures
0 unicast RPF drop, 0 suppressed RPF drop
Sent:  557 generated, 10 forwarded
0 fragmented into 0 fragments, 0 failed
0 encapsulation failed, 0 no route, 0 too big
Mcast: 514 received, 538 sent

ICMP statistics:
Rcvd: 227 input, 0 checksum errors, 0 too short
0 unknown info type, 0 unknown error type
unreach: 0 routing, 0 admin, 0 neighbor, 0 address, 0 port
parameter: 0 error, 0 header, 0 option
0 hopcount expired, 0 reassembly timeout,0 too big
5 echo request, 0 echo reply
0 group query, 0 group report, 0 group reduce
0 router solicit, 203 router advert, 0 redirects
8 neighbor solicit, 11 neighbor advert
Sent: 231 output, 0 rate-limited
unreach: 0 routing, 0 admin, 0 neighbor, 0 address, 0 port
parameter: 0 error, 0 header, 0 option
0 hopcount expired, 0 reassembly timeout,0 too big
0 echo request, 5 echo reply
0 group query, 0 group report, 0 group reduce
0 router solicit, 205 router advert, 0 redirects
11 neighbor solicit, 10 neighbor advert

UDP statistics:
Rcvd: 304 input, 0 checksum errors, 0 length errors
0 no port, 0 dropped
Sent: 314 output

TCP statistics:
Rcvd: 0 input, 0 checksum errors
Sent: 0 output, 0 retransmitted

Here, you can see the general detailed IPv6 statistics, as well as ICMP, UDP and TCP statistics.

If you suspect your router is not functioning correctly, make sure you master these troubleshooting commands. Everything you need to know about the IPv6 configuration and statistics will be found in the output of these powerful commands.

We hope you found this topic helpful in your preparation for the CCNA exam. Mastering the techniques described in this topic will not only help you when you’ll take the CCNA exam, but also in real life, because many networks begin to implement IPv6 along with IPv4 these days. We are proud to provide you with real life scenarios to help you achieve excellence in the networking world.

The main feature of IPv6 are described in the sections below

Larger Address Space

IPv6 addresses are 128-bits long which gives us a theoretical address space of 3.4 x 10³⁸ addresses, like IPv4 some address space is reserved for special purpose but still there is a huge number of public routable addresses.

Aggregation

A larger address space allows for large address allocations to ISPs and Organization. This allows them to use a single prefix for the entire network making summarization easy and flexible which turn promotes efficient and scalable routing.

New Improved Header Format

Optional and non-essential fields are removed from the IPv6 Header and are moved the Extension Header that is placed after the IPv6 Header. Fewer fields of fixed lengths mean Header overhead is minimized and processing performance is improved.  Another significant enhancement is that all routers in a path do need to do checksum recalculation for an IPv6 Packet instead error detection is handled by data-link layer technologies checksums of the end-to-end connection at transport layer.  Figure 1 shows an IPv6 Header followed by Extension Header.

Allocation

IPv6 addresses are composed of two parts, 64-bit Network Prefix and 64-bit host part. The IPv6 address allocation follows a generally acceptable assignment policy as shown in figure 1. This allows for an efficient, hierarchical, and summarizable routing infrastructure.

Easy Address Assignment Methods

IPv6 has three assignment methods

• Static

• DHCPv6 (Stateful)

• Autoconfiguration (Stateless)

An IPv6 host can configure a link-local address for each interface automatically. By using ICMPv6 router discovery messages, a host can also determine the addresses of routers, additional addresses, and other configuration parameters.

Built-in Security

IPSec is built into IPv6 unlike IPv4 in which it is optional. IPSec requirement is mandatory in IPv6 Protocol Suite Implementation. IPv6 networks have potentially more end-to-end security because of IPSec availability on all nodes.

Extensibility

New futures for IPv6 can be added through the use of Extension Headers. At present there are various Extension Headers specified for QoS, Security, Mobility and Routing purposes.

Mobility

Mobility is built in to IPv6 which allows any node to use Mobile IP. Mobility is achieved using Mobility Extension Headers.

Better Quality of Service Support

IPv6 Header includes a new field called Flow Label that allows routers to identify and provide special handling for packets that belong to a particular flow. This field allows for easier identification of traffic without doing any tricks even when the packet payload is encrypted with IPSec.

Neighbor Discovery Protocol

Neighbor Discovery Protocol uses ICMPv6 messages to perform various functions such as

• Stateless Auto-configuration

• Router Discovery

• Prefix Discovery

• Address Resolution

• Neighbor Unreachability Detection

• Link MTU Discovery

• Duplicate Address Detection

• Next Hop Determination

Transition

The transition options supported by IPv6 to transition from IPv4 are another key feature of the protocol. Many Transitions mechanism are available for different scenarios. They are mentioned below

• Dual-Stack
• Tunneling IPv6 over IPv4 networks
• Protocol Translation

Within each option are various different techniques to support transition. A few tunneling mechanism are mentioned below

• Static GRE Tunnels

• 6to4 Tunnels

• ISATAP

• Automatic IPv4-Compatible IPv6 Tunnels

In this article we covered a some of the features of IPv6, these rich features enable easy deployment, migration and operation of IPv6 networks.

Routers are computers. They have a CPU, memory, different expansion cards and they all run an operating system, the Cisco Internetworking Operating System (IOS). When a router is powered on, it goes through four major phases until the IOS loads completely:

1.       Performs the POST

2.       Loads the bootstrap program

3.       Locates and loads the Cisco IOS software

4.       Locates and loads the startup configuration file or enters the setup mode

The Power-On Self Test (POST) is a process which occurs on almost every computer during bootup. This process is used to test the router hardware. When the router is powered on, software on the ROM chip performs tests on several hardware components, such as CPU, RAM and NVRAM. After the POST is completed, the router executes the bootstrap program.

After the POST has passed all the tests, the router copies the bootstrap program from ROM into RAM. After the program got into RAM, the CPU executes the instructions in the bootstrap. The main task of the bootstrap is to locate the Cisco IOS and load it into RAM. If you are connected with a console cable, at this point you will see text like the following on the console, depending on your platform:

System Bootstrap, Version 12.3(8r)T8, RELEASE SOFTWARE (fcl)
Cisco 1841 (revision 5.0) with 114688K/16384K bytes of memory.

Generally, the IOS is stored in the flash memory, but it can be also stored in other places, such as a TFTP server. At the third step, the router loads the IOS image into RAM for execution by the CPU. If the IOS image can’t be located, a minimal version of the IOS is loaded from ROM into RAM. This version can be used to diagnose problems and load a complete version of IOS. When the IOS begins to load, you may see a string of pound signs (#), while the image decompresses.

Self decompressing the image :
###################################################################### [OK]

The last step in the router boot-up process is to locate and load the startup configuration file, also known as startup-config, in NVRAM. The startup-config contains configuration commands and parameters such as interface addresses, routing information, passwords and any other configurations saved by the network administrator. The router copies the startup-config from NVRAM into RAM as running-config. If a startup-config file is not found, the router prompts the user to enter setup mode. The setup mode is a series of questions prompting the user for basic configuration information. When the startup-config is not found, you will see a prompt like the following:

Would you like to enter the initial configuration dialog? [yes/no]

After the router is up and running, you can check the show version command to check some of the basic hardware and software components of your router.

Router>show version

Cisco Internetwork Operating System Software
IOS ™ C2600 Software (C2600-I-M), Version 12.2(28), RELEASE SOFTWARE (fc5)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by cisco Systems, Inc.
Compiled Wed 27-Apr-04 19:01 by miwang
Image text-base: 0×8000808C, data-base: 0×80A1FECCROM: System Bootstrap, Version 12.1(3r)T2, RELEASE SOFTWARE (fc1)
Copyright (c) 2000 by cisco Systems, Inc.
ROM: C2600 Software (C2600-I-M), Version 12.2(28), RELEASE SOFTWARE (fc5)

System returned to ROM by reload
System image file is “flash:c2600-i-mz.122-28.bin”

cisco 2620 ( MPC860) processor (revision 0×200) with 60416K/5120K bytes of memory

.
Processor board ID JAD05190MTZ (4292891495)
M860 processor: part number 0, mask 49
Bridging software.
X.25 software, Version 3.0.0.
1 FastEthernet/IEEE 802.3 interface(s)
32K bytes of non-volatile configuration memory.
63488K bytes of ATA CompactFlash (Read/Write)

Configuration register is 0×2102.

As you can see, you will find here information like: IOS version, bootstrap version, location of the IOS image, CPU type, amount of memory, interfaces, amount of NVRAM, amount of flash memory, and the configuration register.

The configuration register has several uses, including password recovery. The default setting is 0×2102, which tells the router to load the Cisco IOS image from flash memory and the startup configuration file from NVRAM. We will talk about setting the configuration register to 0×2142 at a later time to ignore the configuration stored in the startup config if we have a situation where we forget the password or such.

Understanding how a router boots up is important for your troubleshooting tasks. We hope you found this CCNA topic helpful and we will discuss more about IOS configuration and troubleshooting in other topics from our Cisco CCNA exam preparation series. ]]> http://www.certificationkits.com/blog/component/wordpress/2011/04/01/ccna-certification-router-boot-up-process/feed/ 0