Ch 6 Flashcards

1
Q

IPv6 traffic class field

A

1 bytes
replaces DS field

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2
Q

version field

A

4 bit value
IPv4 (0100) vs IPv6 (0110)

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3
Q

next hop address

A

IP of the next router to forward the packet for that network

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4
Q

2 Windows commands to show routing table

A

route print
netstat -r

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5
Q

packet sizes

A

IPv4 - 20 bytes

IPv6 - 40 bytes

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6
Q

IPv6 payload length field

A
16 bits (2 bytes)
length of data payload of packet
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7
Q

3 Cisco router types

A
Branch (ISR G2)
WAN (Catalyst switches, Aggregation Services Routers)
Service Provider (Carrier Routing System and 7600 routers)
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8
Q

in-band vs out-of-band

A

in-band carry user traffic and require IP addressing
out-of-band dedicated to configure, manage, and troubleshoot, don’t carry user traffic

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9
Q

definition of routing

A

the process of sending packets to hosts on a remote network

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10
Q

IPv6 hop limit field

A
8 bit (2 bytes)
replaces TTL field
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11
Q

next header

A
8 bits (2 bytes)
same as IPv4 protocol field
indicates data payload type
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12
Q

HWIC

A

high speed WAN interface card

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13
Q

Basic characteristics of a IP

A

Connectionless
Best effort delivery
Media independent

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14
Q

ICMP

A

Internet Control Message Protocol

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15
Q

IPv6 extension headers EH

A

provide optional network layer information
placed between IPv6 header and payload
used for fragmentation, security, mobility

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16
Q

definition of hop

A

each router that a packet crosses to reach its destination

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17
Q

IOS command for viewing routing table

A

show ip route

18
Q

fragmentation definition

A

when an intermediate device splits up a packet to forward it over a medium with a smaller MTU
routers don’t fragment IPv6 packets

19
Q

default route definition

A

a route that device uses to send a packet to a remote network when network doesn’t match any other routes.

20
Q

TTL Time to Live

A

1 byte
limits the lifetime of packet
each hop TTL is decremented
if 0, router sends ICMP Time Exceeded message

21
Q

improvements of IPv6

A

longer addresses (128 bits - 16 bytes) vs (32 bits - 4 bytes)
headers have fewer fields
NAT not needed

22
Q

MTU maximum transmission unit

A

the maximum size of the PDU that a given medium can support
data link layer tells network layer its MTU

23
Q

best effort definition

A

packet delivery is not guaranteed
cannot retransmit undelivered or corrupt packets

24
Q

function of network layer

A

enable the transport of data from one network to another.

25
boot process
1. perform post and load bootstrap (ROM) 2. load IOS either from flash or TFTP server. If failure, use limited IOS from ROM (hash symbols) 3. load startup-config from NVRAM
26
gateway of last resort
default route route that router will use if packet does not match entry in routing table
27
Differentiated Services (DiffServ)
1 byte used for priority formerly called Type of Service DSCP Differentiated Services Code Point (6 bits) ECN Explicit Congestion Notification (2 bits)
28
Four basic processes of network layer
Addressing end devices Encapsulation (adding network layer headers) Routing De-encapsulation
29
IPv6 flow label field
``` 20 bits (2.5 bytes) how router should handle packet ``` packets with the same flow field value should be handled the same
30
Cisco routing table abbreviations
``` C = directly connected network L = local interface (IP on interface on router) S= static router D = EIGRP enchanced interior gateway routing protocol O = OSPF Open Shortest Path First ```
31
3 fields used for fragmentation
Identification Flags Fragment offset
32
advanced integration module
offloads processor-intensive functions away from main CPU
33
IPv6 simplified header benefits
better routing efficiency no requirement for processing checksums more efficient extension header mechanisms flow label field
34
connectionless definition
no connection with the destination is established before sending packets the recipient is not notified in advance the benefit is there is less overhead for IP do not know if: 1. receiver present 2. packet arrived 3. receiver can read the packet
35
Cisco types of memory
RAM - routing table, arp table, running config, packet buffer NVRAM - startup config file Flash - IOS files ROM - POST, limited IOS (backup), firmware for boot
36
of unique addresses
IPv4 - 4.2 billion IPv6 - 340 undecillion (10^36)
37
limitations of IPv4
IP address depletion routing table expansion lack of end-to-end connectivity (NAT hides device address)
38
metric
how a router decides which route to use if there are two possible routes to the same destination represents router preference
39
elements of routing table
router source (how router learned network) destination network administrative distance metric next-hop address route timestamp outgoing interface
40
Protocol field
1 byte indicates data payload type common values: ICMP - 1 TCP - 6 UDP - 17
41
administrative distance
trustworthiness of router lower values mean higher trustworthiness
42
IPv4 - 3 fields used for validation
``` IHL - Internet Header Length (4 bits) Total Length (2 bytes) Header Checksum (2 bytes) ```