Terminology 2. Flashcards
What are the two parts of a MAC address?
OUI - Organisationally Unique Identifier
Vendor assigned
What is bit 47 of a MAC address?
I/G address bit (Individual/Group).
If 0, address is unicast address, if 1 it is a multicast/broadcast address
LSB of first octet
What is bit 46 of a MAC address?
L/G address bit (Local/Global). Is the address is a burned-in address (BIA), or changed locally.
When set to 1, the address only has to be unique to the local network.
2nd LSB of first octet
What is the structure of an Ethernet_II frame?
Preamble - 7 octets
SOF - 1 octet
Destination - 6 octets
Source - 6 octets
Type - 2 octets *
Data and Padding - 46 - 1500 octets
FCS - 4 octets
What is the structure of an 802.3_Ethernet frame?
Preamble - 7 octets
SOF - 1 octet
Destination - 6 octets
Source - 6 octets
Length - 2 octets *
Data and Padding - 46 - 1500 octets
FCS - 4 octets
What is encapsulating a frame with a different type of frame called?
Tunnelling
In an ethernet frame, what is the preamble comprised of?
7 octets of an alternating 10101010 pattern
In an ethernet frame, what is the SOF
Start of frame or synch. The SOF is 10101011, where the last pair of 1’s allows the receiver to predict the beginning of a frame.
802.3 ethernet can not identify the network layer protocol. What sort of protocol is required for it to be used?
A proprietary LAN protocol, such as IPX.
What is the ethertype for IPv4?
0x0800
What is the ethertype for ARP?
0x0806
What is the ethertype for VLAN tagged?
0x8100
What is the ethertype for IPv6?
0x86DD
What are the original IEEE 802.3 standards? (3)
10Base2 (thinnet)
10Base5 (thicknet)
10BaseT
What is the access method defined in 802.3? And what is its limitation?
AUI (Attachment Unit Interface), which only allows one bit at a time transmission.
802.3u (fast ethernet) introduced a new interface, what was it, how many bits at a time does it support?
MII (Media Independent Interface) - uses a nibble (4 bits at a time)
Gigabit ethernet introduced a variation on the MII, what was it, how many bits at a time does it support?
GMII (Gigabit Media Independant Interface) - transmits 8 bits at a time.
CWDM?
Coarse Wavelength Division Multiplexing
18 channels over a single fibre
What are two common wavelengths for CWDM?
1310nm and 1550nm
How many channels does CWDM allow for?
18
DWDM
Dense Wavelength Division Multiplexing
80+ channels
What is the maximum distance of CWDM?
70km
How many channels does DWDM support?
80+
What is the max speed DWDM supports?
400 Gbps per channel
How far apart are CWDM channels?
20nm
How far apart are DWDM channels
0.8nm
What are the two LEDs typically found on a NIC called?
- The link light - usually green, indicates that an ethernet connection has been established.
- The activity LED - flickers to indicate activity.
Other LEDs may indicate the speed of the connection.
A NIC is a layer _____ device.
2
A Hub is a layer ____ device.
1
What is the primary function of a Bridge?
To break up collision domains.
A Bridge is a layer ___ device.
2
What are the 3 significant differences between a switch and a hub?
- A switch recognises frames
- A switch pays attention to the source and destination MAC addresses
- A switch makes each port a unique collision domain
A switch is a layer ____ device
2
A router is a layer ____ device
3
The term multi-layer switch refers to a ________.
router
What are the tree zones a triple homed router defines?
- External (untrusted)
- Internal (trusted)
- DMZ or Screened subnet (trusted)
HIDS
Host-based Intrusion Detection System (runs on one computer)
PIDS
Protocol-based Intrusion Detection System (monitors traffic for one protocol on one server)
APIDS
Application Protocol-Based IDS (monitor for a group of servers running the same application)