Ccnp Ipv6 Exam Prep

8/13/2019 Ccnp Ipv6 Exam Prep

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CH16 Exam PrepDesign Review

Design Goal Possible Implementation Choices Covered in This Chapter

An IPv6 design suggests that all client hosts should

dynamically learn their IPv6 addresses. Which tools can be

used? (2)

Stateful DHCP and Stateless autoconfiguration

A plan shows the use of stateless Autoconfiguration. What

functions should we expect the IPv6 DHCP server to

perform?

DNSv6 Server Addresses

Notable Questions from This Chapter to Consider During an Implementation Plan Peer Review

Question Answers

An implementation plan states that router IPv6 address

should be assigned as obvious values, using the lowest

numbers in the range per each assigned prefix. What

configuration methods could be used to configure these

low address values?

Static Ipv6 configuration, or Static EUI-64 configuration

and configuring the router interface MAC to be a simple

low address.

A plan calls for the use of stateless autoconfig for client

hosts. What must be configured on the routers to support

this process?

Ipv6 unicast routingand an ipv6 unicast address

configuring on the interface attached to the LAN where

the hosts reside.

Implementation Plan Configuration Memory Drill

Feature Configuration Commands / Notes

Configure the full global unicast address on an interface. Ipv6 address interface-id/length

Configure the unicast IPv6 prefix on an interface, and let

the router add the interface ID.

Ipv6 addressprefix/length eui-64

Configure an interface to find its unicast IPv6 address usingstateless autoconfig.

Ipv6 address autoconfig

Configure an interface to enable IPv6 and use another

interfaces IPv6 address as needed.

Ipv6 address unnumbered interface

Enable IPv6 on an interface and do not configure a unicast

IPv6 address.

Ipv6 enable

Configure the link local address of an interface. Ipv6 address interface-id/length link-local

Verification Plan Memory Drill

Information Needed Commands

All IPv6 routes Show ipv6 route

A single line per IPv6 address Show ipv6 int brief

Detailed information about IPv6 on an interface, including

multicast addresses

Show ipv6 int interface

The MAC address used by an interface Show int interface

The MAC addresses of neighboring IPv6 hosts Show ipv6 neighbors

The information learned from another router in an RA

message

Show ipv6 router


2/13

Review all the Key TopicsKey Topics for CH16

Key Topic

Element

Description Page

Number

Figure 16-1 Conceptual view of IPv6 global routes 535

List Rules for abbreviating IPv6 addresses 536

List Rules about how to write IPv6 prefixes 538

Figure 16-3 IPv6 public prefix assignment concepts 540List IPv6 subnetting process 541

Figure 16-5 IPv6 subnetting concepts 542

List Three steps used by the stateless autoconfig feature 545

Figure 16-8 IPv6 address format when using EUI-64 548

Table 16-7 Comparisons of Stateful and Stateless DHCP 549

List IPv6 address types (unicast, multicast, and anycast) 550

Figure 16-10 Link local address format 552

Table 16-9 Address types and prefixes 552

Figure 16-11 NDP concepts 555

CH16 Memory TablesExample IPv6 Prefixes and Their Meanings

Term Assignment Example from Chapter 16

Registry prefix IANA to RIR 2000::/12

ISP prefix RIR to ISP 2000:1111::/32

Site prefix or global routing prefix ISP to Site 2000:1111:AAAA::48

Subnet prefix Site Engineer subnets 2000:1111:AAAA:1::/64

Although an RIR can assign a prefix to an ISP, an RIR may also assign a prefix to other internet registries, which might

subdivide and assign additional prefixes, until eventually an ISP and then their customers are assigned some unique

prefix.

Summary of IPv6 Address Assignment for Global Unicast Addresses

Method Dynamic or Static Prefix and length

learned from

Host learned

from

Default router

learned from

DNS addresses

learned from

Stateful DHCP Dynamic Stateful DHCPv6

Server

Stateful DHCPv6

Server

NDP Stateful DHCP

Stateless

autoconfig

Dynamic NDP EUI-64 NDP Stateless DHCP

static

configuration

Static Configuration Configuration NDP Sttateless DHCP

Static config with

EUI-64

Static Configuration EUI-64 NDP Stateless DHCP


3/13

Details of the RS/RA Process

Message RS RA

Multicast destination FF02::2 FF02::1

Meaning of Multicast address All Routers on the local-link All Nodes on the local-link

Comparing Stateless and Stateful DHCPv6 ServicesFeature Stateful DHCP Stateless DHCP

Remembers IPv6 address (state

information) of clients that make

requests

Yes No

Assigns IPv6 address to client Yes No

Supplies useful information, such as

DNS server IP addresses

Yes Yes

Most useful in conjunction with

stateless autoconfiguration

No Yes

Common Link-Local Multicast Addresses

Type of Address Purpose Prefix Easily Seen Hex Prefix(es)

Global unicast Unicast packets sent

through the public Internet

2000::/3 2 or 3`

Unique local Unicast packets inside one

organization

FD00::/8 FD

Link local Packets sent in the local

subnet

FE80::/10 FE8, FE9, FEA, FEB

Site local Deprecated; originally

meant to be used like

private IPv4 addresses

FEC0::/10 FEC, FED, FEE, FEF

Unspecified An address used when a

host has no usable IPv6

address

::/128 N/A

Loopback Used for software testing,

like IPv4s 127.0.0.1

::1/128 N/A

IPv6 RFCs define the FE80::/10 prefix, which technically means that the first three hex digits could be FE8, FE9, FEA, or

FEB. However, bit positions 11-64 of link local addresses should be 0, so in practice, link local addresses should always

begin with FE80.


4/13

Common Multicast Addresses

Purpose IPv6 Address IPv4 Equivalent

All IPv6 nodes on the link FF02::1 Broadcast

All IPv6 routers on the link FF02::2 N/A

OSPF messages FF02::5, FF02::6 224.0.0.5, 224.0.0.6

RIP-2 messages FF02::9 224.0.0.9

EIGRP messages FF02::A 224.0.0.10

DHCP relay agents (routers that

forward to the DHCP server)

FF02:1:2 N/A

DHCP servers (site scope) FF05::1:3 N/A

All NTP servers (site scope) FF05::101 N/A

Router IOS IPv6 Configuration Command Reference

Command Description

ipv6 address address/length Assign static ipv6 address

ipv6 addressprefix/length eui-64 Assign prefix/length and let router dervie the interface-id

using the link address (of the lowest numbered LANinterface if configuring a serial interface.)

ipv6 address autoconfig Configure a router interface for stateless

autoconfiguration

ipv6 address dhcp Configure a router interface to use stateful DHCP

ipv6 unnumbered interface-type number Configure a router interface to use the ipv6 address of the

interface stated in the configuration

ipv6 enable Enable ipv6 on a router interface, thereby telling the

router to create a link-local address

ipv6 address address link-local Statically configuring the link-local address on a router

interface.

ipv6 address address/length anycast Assinging an ipv6 address as anycast

Define Key TermsTerm Definition

Global Unicast Address Globally routable ipv6 address

Link Local Address FE80::/10, local link address used for link local communication, derived by EUI-64

Unique Local Address Ipv6 private addressing FD00::/8

Stateful DHCP Stateful DHCP is the same thing as Ipv4 DHCPkeeps track of all state information while

providing prefix/length/interfaceid/and DNS. NDP still provides default routers though.

Stateless DHCP Only provides DNSv6 server addressesStateless Autoconfig Dynamic address assignment, interface or host finds the prefix/length and default router

using NDP, while the interface-id is derived using EUI-64

Neighbor Discovery

Protocol (NDP)

NDP is the protocol responsible for DAD, RS, RA, NS, NA

Neighbor Solicitation (NS) Used like ARP

Neighbor Advertisement

(NA)

Used like ARP response

Router Solicitation (RS) Used to obtain prefix/length and default router information

Router Advertisement

(RA)

Used to respond to an RS with prefix/length and default router information


5/13

Solicited Node Multicast

Address

FF02::1:FF00:0/104the last 24 bits are derived from the last 24 bits of every unicast

address assigned to the host or interface. For each unicast address this group is joined.

Duplicate Address

Detection (DAD)

Host or interface sends a NS to its solicited node multicast address. If it gets a response

then the unicast address is a duplicate.

Inverse Neighbor

Discovery

Used like InARP

CH17 Exam PrepNotable Questions from This Chapter to Consider During an Implementation Plan Peer Review

Question Answers

A RIPng implementation plan lists two neighbor routers

with unicast IPv6 addresses 2000::1/64 and 2001::2/64,

respectively. Will this cause a neighborship issue?

RIPng doest have any concept of neighbors, but the

routers will exchange routes just fine.

Same issues as in the previous row, but the plan uses

EIGRP for IPv6.

EIGRP neighbors do not have to share a common

prefix/length to become neighbors or exchange routes

A plan shows a planned config for a new router, with no

IPv4 addresses, IPv6 addresses on all interfaces, and EIGRP

for IPv6 configuration. What potential issues should you

look for in the configuration? (3)

Router ID

EIGRP process shutdown

Interface configuration`

Same scenario as the previous row, but with OSPFv3. Router ID

Interface configuration

OSPF starts up already, so no need to issue a no shut

The plan shows an EIGRP for IPv6 and OSPFv3 domain with

mutual redistribution. The configuration shows a

redistribute eigrp 1 command under the OSPF process.

What kinds of routes should be redistributed? Which

kinds will not?

All routes in the routing table will be redistributed that

have been leared via EIGRP. The following routes will not

be redistributed:

LC

C

Link Local



Assuming IPv6 routing and IPv6 addresses have already

been configured, configure RIPng.

Ipv6 router ripprocess-name

Interface interface

Ipv6 ripprocess-name


been configured and no IPv4 addresses exist on the router,

configure EIGRP for IPv6.

Ipv6 router eigrpasnEigrp router-idx.x.x.x

no shut

Interface interface

Ipv6 eigrp asn


been configured and no IPv4 addresses exist on the router,

configure OSPFv3.

Ipv6 router ospf Process-id

Router-idx.x.x.x

Interface interface

Ipv6 ospfprocess-id area area

Configure RIPng to redistribute routes from OSPF process 1

including subnets, and connected interfaces.

Redistribute OSPF 1 include-connected


6/13



All IPv6 routes show ipv6 route

Details about a given IPv6 prefix show ipv6 route address/prefix

All routes within a given IPv6 prefix Show ipv6 routeprefix/length longer-prefixes

All RIP-learned IPv6 routes Show ipv6 route rip

All next-hop IPv6 addresses used by RIP routes Show ipv6 rip next-hops

The interfaces on which RIP is enabled Show ipv6 protocols

All EIGRP-learned IPv6 routes Show ipv6 route eigrp

All EIGRP neighbors Show ipv6 eigrp neighbors

Summary of the EIGRP topology table Show ipv6 eigrp topology

OSPF router ID and SPF statistics Show ipv6 ospf

List of OSPF neighbors Show ipv6 ospf neighbor

All OSPF-learned IPv6 routes Show ipv6 route ospf

Interfaces enabled for OSPF and their assigned areas Show ipv6 ospf int brief

Show ipv6 protocols

OSPF costs per interface Show ipv6 ospf int brief

Show ipv6 ospf int interface

Summary of the OSPF database Show ipv6 ospf database


Key Topic

Element

Description Page

Number

Table 17-3 Comparisons between RIP-2 and RIPng 574

List Configuration steps for RIPng 575

Table 17-5 Comparisons between EIGRP for IPv4 and EIGRP for IPv6 581

List Configuration steps for EIGRP for IPv6 582

List Decision process for choosing an EIGRP for IPv6 router ID 583

Table 17-7 Comparisons between EIGRP for IPv4 and EIGRP for IPv6 588

List Additional explanations of key differences between OSPFv3 and OSPFv2 589

List Configuration steps for OSPFv3 590

List Similarities and differences with IPv4 and IPv6 redistribution 595


7/13

CH17 Memory TablesComparing RIP-2 to RIPng

Feature RIP-2 RIPng

Advertises routes for Ipv4 Ipv6

RIP messages use these Layer 3 / 4 protocols Ipv4 / UDP Ipv6 / UDP

UDP Port 520 521Use Distance Vector Yes Yes

Default Administrative distance 120 120

Supports VLSM Yes Yes

Can perform automatic summarization Yes No

Uses Split Horizon Yes Yes

Uses Poison Reverse Yes Yes

30 second periodic full updates Yes Yes

Uses triggered updates Yes Yes

Uses Hop Count metric Yes Yes

Metric meaning infinity 16 16

Supports route tags Yes Yes

Multicast Update destination 224.0.0.9 FF02::9

Authentication RIP specific Ipv6 AH/ESP

Comparing Verification Commands: show ip and show ipv6

Function IPv4 IPv6

All routes show ip route Show ipv6 route

All RIP learned routes Show ip route rip Show ipv6 route rip

Details on the routes for a specific prefix Show ip route

prefix/length

Show ipv6 route

prefix/lengthInterfaces on which RIP is enabled Show ip protocols Show ipv6 protocols

List of routing information sources Show ip protocols Show ipv6 rip next-

hops

Debug that displays sent and received Updates Debug ip rip Debug ipv6 rip


8/13

Comparing EIGRP for IPv4 and IPv6

Feature EIGRP for IPv4 EIGRP for IPv6


Layer 3 protocol for EIGRP messages Ipv4 Ipv6

Layer 3 header protocol type 88 88

UDP Port N/A N/A

Uses Successor, Feasible Successor logic Yes Yes

Uses Dual Yes Yes


Can perform automatic summarization Yes N/A

Uses triggered updates Yes Yes

Uses composite metric, default using bandwidth and delay Yes Yes

Metric meaning infinity 2^32-1 2^32-1


Multicast Update destination 224.0.0.10 FF02::A

Authentication EIGRP specific Ipv6 AH/EST

Comparing EIGRP Verification Commands: show ip and show ipv6Function show ip show ipv6

All routes Show ip route Show ipv6 route

All EIGRP learned routes Show ip route eigrp Show ipv6 route eigrp

Details on the routes for a specific prefix Show ip routeprefix/length Show ipv6 routeprefix-length

Interfaces on which EIGRP is enabled, plus

metric weights, variance, redistribution, max-

paths, admin distance

Show ip protocols Show ipv6 protocols

List of routing information sources Show ip protocols

Show ip eigrp neighbors

Show ipv6 eigrp neighbors

Hello interval Show ip eigrp interfaces detail Show ipv6 eigrp interfaces detail

EIGRP database Show ip eigrp topology [all-links]

Show ipv6 eigrp topology [all-links

Debug that displays sent and received Updates Debug ip eigrp notifications Debug ipv6 eigrp notifications


9/13

Comparing OSPFv2 and OSPFv3

Feature OSPFv2 OSPFv3


OSPF messages use this Layer 3 protocol Ipv4 Ipv6

IP Protocol Type 89 89

Uses Link State logic Yes Yes


Process to choose RID, compared to OSPFv2 Same Same

LSA flooding and aging compared to OSPFv2 Same Same

Area structure compared to OSPFv2 Same Same

Packet types and uses compared to OSPFv3 (Table 6-4) Same Same

LSA flooding and aging compared to OSPFv2 Same Same

RID based on highest up/up loopback IPv4 address, or highest other IPv4

interface address?

Same Same

32-bit LSID Yes Yes

Uses interface cost metric, derived from interface bandwidth Yes Yes

Metric meaning infinity 2^16-1 2^16-1


Elects DR based on highest priority, then highest RID Yes Yes

Periodic reflooding every 30 minutes 30 minutes

MulticastAll SPF routers 224.0.0.5 FF02::5

MulticastAll designated routers 224.0.0.6 FF02::6

Authentication OSPF specific Ipv6 AH/ESP

Neighbor checks compared to OSPFv2 (table 5-5) Same Same except no

same subnet

check

Multiple instances per interface No Yes

Comparing OSPF Verification Commands: show ip and show ipv6

Function show ipv4 show ipv6

All OSPFlearned routes Show ip route ospf Show ipv6 route ospf

Router ID, Timers, ABR, SPF statistics Show ip ospf Show ipv6 ospf

List of routing information sources Show ip protocols

Show ip ospf neighbor

Show ipv6 ospf neighbor

Interfaces assigned to each area Show ip protocols

Show ip ospf int brief

Show ipv6 protocols

Show ipv6 ospf int brief

OSPF interfacescosts, state, area, number of

neighbors

Show ip ospf int brief Show ipv6 ospf int brief

Detailed information about OSPF interfaces Show ip ospf int interface Show ipv6 ospf int interface

Displays summary of OSPF database Show ip ospf database Show ipv6 ospf databaseDefine Key TermsTerm Definition

RIP Next Generation RIP for ipv6

OSPF Version 3 OSPF for ipv6

EIGRP for IPv6 EIGRP for ipv6


10/13

CH18 Exam PrepDesign Review

Design Goal Possible Implementation Choices Covered in This Chapter

The design states that an Enterprise needs IPv6 support for

most LANs, with a regular high-volume of IPv6 traffic.

Would native IPv6, point-to-point tunnels, or multipoint

tunnels seem most appropriate?

Native ipv6


a set small subset of LANs but that their traffic will be

regular. Would native IPv6, point-to-point tunnels, or

multipoint tunnels seem most appropriate?

Point-to-point tunnels


a set small subset of LANs but that their traffic will be

irregular and occasional. Would native IPv6, point-to-point

tunnels, or multipoint tunnels seem most appropriate?

Multipoint tunnels

The plan calls for IPv6 tunneling so that new routers, when

added to the tunnel, do not require additional

configuration on existing routers. What type tunnel would

you choose, and what IPv6 address ranges?

6to4 tunneling using the range 2002::/16

Notable Questions from This Chapter to Consider During an Implementation Plan Peer Review

Question Answers

The plan calls for the use of OSPFv3 along with the

implementation of IPv6 tunnels. What tunnel types do you

expect to find the sample configurations? (2)

MCT

GRE

The planning diagrams show multipoint tunnels, with IPv6

addresses that embed an IPv4 address in the last two quartets.

What type of tunneling do you expect to see in the sample

configurations?

ISATAP

The plan lists a sample configuration with the command tunnel

mode ipv6ip under a tunnel interface. What type of tunneling is

used in this case?

MCT

Same question as the previous row, but the command listed as

tunnel mode ipv6ip isatap.

ISATAP

Same question as the previous row, but the command listed is

tunnel mode gre ip.

GRE

Same question as the previous row, but the command listed is

tunnel mode ipv6ip 6to4

6to4

A plan shows the use of a manually configured tunnel and an

ISATAP tunnel. What tunnel subcommand would you expect tosee for the point-to-point tunnel, but not the multipoint tunnel?

tunnel destination for the point-to-point MCT, but

not the multipoint tunnel.


11/13



Configure an IPv6 manually configured tunnel using a

loopback IPv4 address. Ignore IPv6 addressing and routing

configuration.

Int l1

Ip address x.x.x.x

Int tunnel0

Ipv6 address

Tunnel mode ipv6ip

Tunnel source l1

Tunnel destination y.y.y.yAdd IPv6 addressing and routing configuration to the

previous rows list. Assume EIGRP for IPv6 ASN 1 is

preconfigured.

Ipv6 unicast-routing

Int tunnel0

Ipv6 address

Ipv6 eigrp 1

Configure an IPv6 GRE tunnel using a loopback IPv4

address. Ignore IPv6 addressing and routing configuration.

Int l1

Ip address x.x.x.x

Int tunnel0

Tunnel mode gre ip

Tunnel source l1

Tunnel destination y.y.y.y

Configure an IPv6 automatic 6to4 tunnel using a loopbackIPv4 address. Include only IPv6 configuration required for

the tunnel to pass IPv6 traffic. Assume all hosts use

addresses in the 2002::/16 range.

Ipv6 unicast-routingInt l1

Ip address x.x.x.x

Int tunnel0

Ipv6 address z.z.z.z

Tunnel mode ipv6ip 6to4

Tunnel source l1

Ipv6 route 2002::/16 tunnel0

List steps to migrate from the automatic 6to4 tunnel from

the previous row to a comparable ISATAP tunnel

Interface tunnel0

Ipv6 address prefix/64 eui-64

Tunel mode ipv6ip isatap

No ipv6 route 2002::/16 tunnel0

Ipv6 route prefix/length tunnel0 next-hop



Tunnel interface status for IPv6. Show ipv6 interface brief

Show ipv6 interface tunnel0

Show interfaces tunnel0

Tunnel interfaces IPv6 address(es). Show ipv6 interface brief

Show ipv6 interface tunnelConnected routes related to the tunnel. show ipv6 route

The tunnel source and destination IPv4 addresses. Show interface tunnel

Test the tunnel to see if it can pass traffic. Ping

traceroute


12/13


Key Topic

Element

Description Page

Number

Figure 18-3 Point-to-point IPv6 tunnel concept 614

Figure 18-4 Multipoint IPv6 tunnel concept 616

Table 18-2 Comparisons of four IPv6 tunnel types 617

Figure 18-5 NAT-PT concepts 618List Manually configured tunnel configuration checklist 620

List Configuration differences between GRE and manually configured IPv6 tunnels 625

Table 18-3 Comparisons of manually configured tunnels and GRE tunnels 626

Figure 18-8 Address planning for automatic 6to4 tunnels 628

List Configuration checklist for automatic 6to4 tunnels 629

List Comparisons of automatic 6to4 and ISATAP tunnels 634

Figure 18-10 ISATAP tunnel logic 635

List Modified EUI-64 rules for forming ISATAP IPv6 addresses 636

List ISATAP tunnel configuration checklist 636

Table 18-4 Comparisons of Automatic 6to4 and ISATAP tunnels 640

CH18 Memory TablesComparing Manual and GRE IPv6-over-IP Tunnels

Manual Tunnels GRE

RFC 4213 2784

Tunnel mode command Tunnel mode ipv6ip Tunnel mode gre ip

Passenger MTU default 1480 1476

Supports IPv6 IGPs? Yes Yes

Forwards IPv6 multicasts? Yes Yes

Uses static configuration of tunnel

destination?

Yes Yes

Supports multiple passenger

protocols?

No Yes

Link local based on FE80::/96, plus 32 bits from tunnel

source Ipv4 address

Ipv6 EUI-64, using lowest numbered

interfaces MAC address

Comparing IPv6 Multipoint Tunnels

Automatic 6to4 ISATAP

Defined by RFC or Cisco? 3056 4214

Uses a reserved IPv6 address prefix. Yes 2002::/16 No

Supports the use of global unicast addresses? Yes Yes

Quartets holding the IPv4 destination address. 2 and 3 7 and 8

End-user host addresses embed the IPv4 destination? Sometimes No

Tunnel endpoints IPv6 addresses encode IPv4 destination. Sometimes Yes

Uses modified EUI-64 to form tunnel IPv6 addresses? No Yes


13/13

Define Key TermsTerm Definition

Dual stacks

Network Address

TranslationProtocol

Translation (NAT-PT)

tunneling

tunneltunnel interface

point-to-point tunnel

multipoint tunnel

ISATAP tunnel

ISATAP

automatic 6to4 tunnel

manually configured

tunnel

GRE tunnel

Modified EUI-64

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