2 - IPv6 & Network Diagrams

Question 1

NAT

Answer 1

Network Address Translation

Question 2

NAT: Why use it?

Answer 2

Org only has one or a few public address so router at edge translates IPs.

Question 3

NAT: Why does it violate layer separation?

Answer 3

Violates layer separation as it edits layer 2 and 3

Question 4

Dynamic IP Allocaiton

Answer 4

ISPs more customers than IP address. Allocate based on that

Question 5

IPv6 why is it necessary

Answer 5

IPv4 address space ran out in 2019.

Also Class A blocks are lost and D is only for multicast and E is experimental

Question 6

IPv6 address length in bits

Answer 6

128bit address

Question 7

IPv6 facts - length, checksums, headers, broadcast etc

Answer 7

Fixed Length, optional headers are daisy chained
No checksum at network layer
64bits aligned field in header
Auth and privacy capabilities
No more broadcast

Question 8

IPv6 address rep

Answer 8

16 bit fields in case insensitive colon-separated hex rep

Question 9

IPv6: Are leading zeros required?

Answer 9

Leading zeros in field are optional (eg :0000: or :0: or :00: etc)

Question 10

IPv6: When can :: be used?

Answer 10

Successive fields of 0 are :: but only once.

Question 11

IPv6 special addresses

Answer 11

0:0:0:0:0:0:0:1 (::1) Loopback
0:0:0:0:0:0:0:0 (::) unspecified

Question 12

IPv6 URLs

Answer 12

Must be enclosed in brackets

http://[2001:4860:b006::67]:80/
- CUmbersome
- Mostly diagnostic
- Use FQDN instead

Question 13

IPv6 prefix representation (,netmask)

Answer 13

Same as IPv4

slash separator eg /40

Question 14

IPv6 Global Unicast Addresses

Answer 14

Addresses for generic use of IPv6
Hierarchical structure intended to simplify aggregation?

Question 15

IPv6 allocation process

Answer 15

IANA allocates 2000::/3 for initial unicast
Registry gets /12 prefix
Registry allocates /32 (or larger) prefix to ISP
ISP generally allocates /48 prefix to customer
/64 to networks within orgs

Question 16

IPv6 Autoconfig: Link local is always what?

Answer 16

Link local is always fe80::/64

Question 17

IPv6 Autoconfig: Router can announce what addresses?

Answer 17

Router can announce global addresses

Question 18

IPv6 Autoconfig: Clients can use what prefixes?

Answer 18

Clients can use all available /64 prefixes

Question 19

RA ICMP

Answer 19

Router Advertisement Internet Control Message Protocol packets

Question 20

Problems with IPv4 to IPv6 migration

Answer 20

v4 host wanting to talk to v6 host
v6 networks that are only connected by v4 infra

Question 21

IPv4 to IPv6 migration techniques

Answer 21

Dual Stacked hosts/routers
Dual stacked proxies/app level gateways
Tunnelling

Question 22

Different tunnel configurations

Answer 22

Manual
Automatic
Tunnel broker

Question 23

What does a hub do?

Answer 23

Sends frame from one node to all. Repeaters

Question 24

Switches: Learning locations

Answer 24

Learns by looking and the source address of each frame. Builds a forwarding table

Question 25

Switches: Frames or packets?

Answer 25

Switches do not usually know about IP. They only deal with Ethernet frames

Question 26

Switch: What layer?

Answer 26

Layer 2

Question 27

When does a switch broadcast?

Answer 27

When the:
- address is not in forwarding table
- frame is destined to broadcast address
- frame is destined to multicast eth address

Question 28

Routers

Answer 28

Use a routing table to decide where to forward (forwarding table) - looking at IP packets.

Question 29

Routers: What layer?

Answer 29

Layer 3

Question 30

VLANs

Answer 30

Split switches into separate virtual switches

Question 31

VLAN Privacy

Answer 31

Only members of a VLAN can see its traffic and inter VLAN traffic must go through a router.
This also separates broadcast domains.

Question 32

Router network diagram symbol

Answer 32

Cylinder

Question 33

Switch diagram symbol

Answer 33

Rectangle

Question 34

Eth link diagram symbol

Answer 34

Line

Question 35

WAN symbol diagram

Answer 35

Cloud