1.3 Explain the concepts and characteristics of routing and switching. Flashcards
(59 cards)
1
Q
The MAC address
A
- Ethernet Media Access Control address
- –The “physical” address of a network adapter
- –Unique to a device
- 48 bits / 6 bytes long hexadecimal
2
Q
Half-Duplex
A
- A device cannot send and receive simultaneously
* All LAN hubs are half-duplex devices
3
Q
• Full-duplex
A
• Data can be sent and received at the same time
• A properly configured switch interface
will be set to full-duplex
4
Q
CSMA/CD
A
- CS - Carrier Sense MA - Multiple Access
- CD - Collision Detect Two stations talking at once - not used any longer
• Listen for an opening and Don’t transmit if the network is busy
- If a collision occurs Transmit a jam signal
- Wait a random amount of time, then retry
5
Q
CSMA/CA
A
- CA - Collision Avoidance
- Common on wireless networks
- Collision detection isn’t possible
6
Q
Collision Domains
A
Separated by switch/bridge interfaces
7
Q
Broadcast Domains
A
Separated by router interfaces
• Stops at the router
8
Q
Unicast
A
- One station sending information to another station
* Does not scale optimally for streaming media
9
Q
Multicast
A
- Delivery of information to interested systems
* One to many
10
Q
Broadcast
A
- Send information to everyone at once
- One packet, received by everyone
- Routing updates, ARP requests
- Not used in IPv6 - focus on multicast
11
Q
LANs
A
- Local Area Networks
* A group of devices in the same broadcast domain
12
Q
Virtual LANs
A
- Virtual Local Area Networks
- A group of devices in the same broadcast domain
- Separated logically instead of physically
13
Q
802.1Q trunking
A
- Take a normal Ethernet frame
* Add a VLAN header in the frame
14
Q
Spanning Tree Protocol
A
Loop protection
• Connect two switches to each other
• IEEE standard 802.1D to prevent loops
15
Q
Spanning Tree Protocol Port States
A
- Blocking - Not forwarding to prevent a loop
- Listening - Not forwarding and cleaning the MAC table
- Learning - Not forwarding and adding to the MAC table
- Forwarding - Data passes through and is fully operational
- Disabled - Administrator has turned off the port
16
Q
RSTP (802.1w) • Rapid Spanning Tree Protocol (802.1w)
A
- Faster convergence
- From 30 to 50 seconds to 6 seconds
- Backwards-compatible with 802.1D STP
17
Q
Basic Interface Configuration
A
- Needs to match on both sides
- Speed: 10 / 100 /1,000
- Duplex: Half/Full
18
Q
IP address management
A
• Layer 3 interfaces
• VLAN interfaces
• IP address, subnet mask/CIDR block,
default gateway, DNS (optional)
19
Q
VLANs
A
- VLAN assignment
* Each device port should be assigned a VLAN
20
Q
Trunking
A
• Connecting switches together - Multiple VLANs in a single link
21
Q
Tagged and untagged VLANs
A
- A non-tagged frame is on the default VLAN or native VLAN
* Trunk ports will tag the outgoing frames and remove the tag on incoming frames
22
Q
DMZ
A
- Demilitarized zone
* An additional layer of security between the Internet and you
23
Q
Powering devices
A
PoE and POE+ - 15.4 watts DC power
• POE+: IEEE 802.3at-2009 - 25.5 watts DC power
24
Q
Port mirroring
A
- Examine a copy of the traffic
* Port mirror (SPAN), network tap
25
Routing
• Send IP packets across the network
• Forwarding decisions are based
on destination IP address
• Each router only knows the next step
• The list of directions is held in a routing table
• Each router rewrites the frame to add its own data-link header
26
Static routing
• Administratively define the routes - You’re in control
27
Advantages of Static routing
* Easy to configure and manage on smaller networks
* No overhead from routing protocols
* Easy to configure on sub networks (only one way out)
* More secure - no routing protocols to analyze
28
disadvantages of Static routing
* Difficult to administer on larger networks
* No automatic method to prevent routing loops
• If there’s a network change, you have to manually update the routes
29
Dynamic routing
* Routers send routes to other routers
| * Routing tables are updated in (almost) real-time
30
Advantages of Dynamic routing
* No manual route calculations or management
* New routes are populated automatically
* Very scalable
31
Disadvantages of Dynamic routing
* Some router overhead required
| * Requires some initial configuration to work properly
32
Default route
* A route when no other route matches
| * Go that way -> rest of the world
33
AS (Autonomous System)
• “An AS is a connected group of one or more IP prefixes run by one or more network operators which has a run by one or more network operators which has a SINGLE and CLEARLY DEFINED routing policy.”
Gateway Protocols and Exterior Gateway Protocols
34
IGP (Interior Gateway Protocol)
* Used within a single autonomous system (AS)
* Not intended to route between AS
* IPv4 dynamic routing/• IPv6 dynamic routing
* OSPFv2 (Open Shortest Path First)
* RIPv2 (Routing Information Protocol version 2)
* EIGRP (Enhanced Interior Gateway Routing Protocol)
35
EGP (Exterior Gateway Protocol)
* Used to route between autonomous systems
* BGP (Border Gateway Protocol)
* Many organizations use BGP as their EGP
36
Dynamic routing protocols
* Listen for subnet information from other routers
* Provide subnet information to other routers
* Determine the best path based on the gathered information
• Different convergence process
for every dynamic routing protocol
37
Hybrid routing protocols
* A little link-state, a little distance-vector
* BGP (Border Gateway Protocol)
* Determines route based on paths, network policies, or configured rule-sets
38
Link-state routing protocols
* Information passed between routers is related to the
* Faster is always better, right?
* Used most often in large networks
* OSPF - Large, scalable routing protocol
39
Distance-vector routing protocols
* Information passed between routers contains routing tables
* How many “hops” away is another network? The deciding “vector” is the “distance”
* RIP, RIPv2, EIGRP
* Good for smaller networks and Very little configuration
40
The IP address of a device
* Every device needs a unique IP address
* Subnet mask, e.g., 255.255.255.0
* Used by the local workstation to determine what subnet it’s on
* The subnet mask isn’t (usually) transmitted across the network
41
subnwt mask
• The subnet mask determines what part of the IP
• The subnet mask is just as important
as your IP address!
42
IPv4 addresses - Internet Protocol version 4
* OSI Layer 3 address • Since one byte is 8 bits,
| * Maintains an IPv4 routing table
43
IPv6 addresses
• Internet Protocol v6 - 128-bit address
IPv6 address compression
• Uses IPv6 dynamic routing protocols
44
Tunneling IPv6
* 6 to4 addressing
* Send IPv6 over an existing IPv4 network
* Creates an IPv6 based on the IPv4 address
* No support for NAT
* IP protocol 41 - a transition technology
* Tunnel IPv4 traffic on an IPv6 network
45
Teredo/Miredo
* Tunnel IPv6 through NATed IPv4
* End-to-end IPv6 through an IPv4 network
* No special IPv6 router needed
* Miredo - Open-source Teredo for Linux,
46
NDP (Neighbor Discovery Protocol)
* No broadcasts!
* Operates using multicast over ICMPv6
* Neighbor MAC Discovery
* Replaces the IPv4 ARP
47
SLAAC (Stateless Address Autoconfiguration)
• Automatically configure an IP address without a DHCP server
48
DAD (Duplicate Address Detection)
• No duplicate IPs!
49
Discover routers
• Router Solicitation (RS) and Router Advertisement (RA)
50
Finding Router
* ICMPv6 adds the Neighbor Discovery Protocol
* Routers also send unsolicited RA messages • From the multicast destination of ff02::1
* Sent as a multicast
51
• Neighbor Solicitation (NS)
* Neighbor Advertisement (NA)
* Neighbor Advertisement (NA)
* There’s no ARP in IPv6
52
NAT (Network Address Translation)
• Destination address is translated
from a public IP to a private IP
• Does not expire or timeout
Port Forwarding
53
Managing Network Traffic
Packet shaping - • Control by bandwidth usage or data rates
QoS (Quality of Service)
Managing QoS - • Voice over IP traffic has priority over web-browsing, • Prioritize by maximum bandwidth, traffic rate, VLAN, etc.
• CoS (Class of Service)-OSI Layer 2-Differentiated Services (DiffServ)
• OSI Layer 3
54
Packet filtering
• ACLs can evaluate on certain criteria -• Source IP, Destination IP, TCP port numbers, UDP port numbers, ICMP
* Used to allow or deny traffic
* Defined on the ingress or egress of an interface
55
Firewall rules
* Access control lists (ACLs)
* Allow or disallow traffic based on tuples
* Source IP, Destination IP, port number, time of day, application, etc.
* Specific rules are usually at the top
* A logical path
* Implicit deny
56
Circuit switching
• Circuit is established between endpoints before data passes
• POTS and
PSTN (public switched telephone network)
• T1 / E1 / T3 / E3
ISDN• Use a phone number to call another ISDN modem
57
Packet switching
• Data is grouped into packets • The media is usually shared
• SONET, ATM,Frame,Wireless
DSL
58
SDN (Software Defined Networking)
* Networking devices have two functional planes of operation
* Centrally managed - Global view, single pane of glass
* Programmatically configured -• Orchestration - No human intervention
* Open standards / vendor neutral
59
Distributed switching
* Remove the physical segmentation
* A virtual network distributed across all physical platforms
* When a VM moves, the network doesn’t change
