Terminology 5 Flashcards
What is it called when a switch receives frames with the same source MAC address on different interfaces and therefore fails to forward them?
Thrashing the MAC table
What is distributed switching?
When a virtual switch resides on more than one host.
What are the 5 states (in order) that STP transitions through?
Blocking
Listening
Learning
Forwarding
Disabled
What ports do switches send BDPUs out of?
All ports
BPDU
Bridge Protocol Data Units
In STP, what does a port in blocking state do?
Listen to BPDUs and drop all other frames.
What state are ports in when a switch running STP is powered up?
Blocking
In STP, what does a port in listening state do?
Listens to BPDUs checking for loops, it does not update the MAC address table.
In STP, what does a port in learning state do?
Listens to BPDUs, it also populates the MAC address table, but does not forward data frames.
What is the default delay before a port in listening state transitions to learning state?
15s
In STP, what two types of ports enter a forwarding state?
Root and designated
What happens to host data while STP is converging?
It stops.
What is the typical STP convergence time?
50s
What is the RSTP typical convergence time?
5s
What are the 5 problems that can affect data, and that QoS seeks to mitigate?
- Delay
- Dropped packets
- Error
- Jitter
- Out of order delivery
VMPS
VLAN Management Policy Server
How many VLANs can an access port belong to?
1
How many VLANs can a trunk port belong to?
All (1 to 4094)
DTP
Dynamic Trunking Protocol
In what circumstance can an access port be assigned to a second VLAN?
When one is a Voice VLAN, a voice access port can be assigned as well as a data access port.
Why would you use a trunk port for a server rather than an access port?
Because then the server can provide services to multiple VLANs.
How does ISL work?
It adds a header and CRC to a frame which contains VLAN information when sending it out on a trunk port.
How does 802.1Q work?
It inserts an 802.1Q field along with tag information into a frame.
How big is the 802.1Q field and where is it inserted in a frame?
After the source address,
Length 2 bytes
3 bits - user priority filed
1 bit canonical information
12 bits - VLAN identifier
VTP
VLAN Trunking Protocol
What is the main requirement for a switch to be able to share VTP information with other switches?
They must be in the same VTP domain
What ports are used to send VTP information?
Trunk ports
What is used in VTP updates to determine whether a switch needs to overwrite its existing VLAN database?
Revision numbers
What are the 3 requirements for VTP to communicate VLAN information?
- The VTP management domain of both switches must be the same.
- One of the switches has to be configured as a VTP server
- If used, a password has to be set
What are the three modes of VTP operation?
Server
Client
Transparent
What VTP mode is required to add, delete, and create VLANS in a VTP domain?
Server
Where are VLAN configurations saved when a switch is in server mode?
NVRAM
What do switches in transparent mode do?
They don’t participate in the VTP domain, or share its database, but they do forward any VTP advertisements through any configured trunk links.
What is the purpose of transparent mode?
To allow remote switches to receive the VLAN database from a VTP server through a switch that is not participating in the VLAN assignments.
On a switch, what is port security?
Only allowing (a) certain MAC address(es) to access the port
On a switch, what is DHCP snooping?
Only allowing the servers on defined ports to respond to DHCP requests it also builds a bindings table (IP to MAC address)
On a switch, what is ARP Inspection?
Verification of MAC address to IP mappings of each frame (and dropping frames with altered mappings)
DAI
Dynamic ARP Inspection
What is the prerequisite for DAI?
DHCP Snooping
On a switch, what is Flood Guard?
Preventing an attacker from filling up the CAM on a switch with invalid MAC addresses (so that valid traffic is sent out all ports instead of just its designated port)
What two methods does Flood Guard use?
UUFB - Unknown unicast flood blocking
UUFRL - Unknown unicast flood rate limiting
What does UUFB do?
Prevents unknown unicast and multicast traffic flooding at a specific port
What does UUFRL do?
Applies a rate limit globally to unknown unicast traffic on all VLANs
What does BPDU guard do?
Shuts down a port when a BPDU is received.
Which ports should have BPDU guard enabled?
All ports that are not connected to known switches (usually all access ports)
What does Root Guard do, and where is it applied?
It is applied to all ports on the root bridge and prevents these ports from becoming root ports
PAgP
Port Aggregation Protocol (Cisco) - port bonding
LACP
Link Aggregation Control Protocol (IEEE 802.3ad) - port bonding
Port Channeling
Port Bonding
EtherChannel
Cisco proprietary port channeling
What are two other names for Port Mirroring?
SPAN and RSPAN ( Remote SPAN)
SPAN
Switch Port Analyser
RSPAN
Remote Switch Port Analyser
What are the three unlicensed wifi bands released for public use by the FCC?
900 MHz
2.4 GHz
5 GHz
ISM
Industrial, Scientific, Medical
What are the frequencies in the ISM band?
900 MHz and 2.4 GHz
U-NII
UnLicensed National Information Infrastructure
GSM
Global System Mobile
SIM
Subscriber Identity Module
What does GSM require?
A SIM chip
FDMA
Frequency Division Multiple Access
What generation cell technology used FDMA?
1G
TDMA
Time Division Multiple Access
CDMA
Code Division Multiple Access
What does CDMA do?
Assigns a code to each call and spreads data across the spectrum
When was 3G deployed?
1990
When was 4G deployed?
2000
When was 5G deployed?
2014
What is the bandwidth of 3G?
2 Mbps
What is the bandwidth of 4G?
200 to 1000 Mbps
What is the bandwidth of 5G?
1 to 10 Gbps
What are the standards used with 3G?
WCDMA, CDMA-2000
What are the standards used with 4G?
CDMA, LTE, WiMAX
What are the standards used with 5G?
OFDM, MIMO, nm Waves
What is the technology used with 3G?
CDMA/IP
What is the technology used with 4G?
Unified IP, LAN/WAN
What is the technology used with 5G?
Unified IP, LAN/WAN
What band does 802.11b use?
2.4 GHz
What is the maximum data rate of 802.11b?
11 Mbps
What band does 802.11g use?
2.4 GHz
What is the maximum data rate of 802.11g?
54 Mbps
Is 802.11g backward compatible with 802.11b?
Yes
What happens if you use one 802.11b card on an 802.11g network?
Everyone on the network will be forced to run 802.11b modulation.
What modulation technique is employed by 802.11b?
DSSS
What modulation technique is employed by 802.11g?
OFDM
Roughly what percentage of WIFI’s bandwidth is used for the management of the network itself?
70%
What is ‘goodput’?
The actual data throughput
What are the bounds of the 2.4 GHz frequency band?
2.402 to 2.483
How many 2.4 GHz channels are possible?
14
How many 2.4 GHz channels are used in the US?
11
What band does 802.11a use?
5 GHz
What is the maximum data rate of 802.11a?
54 Mbps
How many non-overlapping channels did 802.11a have?
12
With WIFI, what is data-rate shifting?
Negotiating a lower data rate to compensate for an increased distance
What band does 802.11h use?
5 GHz
What standard is 802.11h an extension of?
802.11a
How many non-overlapping channels does 802.11h provide for?
23
What 2 features does 802.11h add?
DFS - Dynamic Frequency Selection
TPC - Transmit Power Control
What does DFS do?
Scan the operating range for radar signals, if it finds them it either abandons the affected channel or marks it as unavailable
What does TPC do?
Allows you to set the transmit power to cover various size ranges.