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Flashcards in Final Theory Deck (53)
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1
Q

Network Design Hierarchy

A

Core, Distribution, and Access layers

2
Q

Failure Domains

A

Areas of networks that are impacted when a critical device/network service experiences problems. Redundant links and enterprise class equipment minimize disruption of a network.

3
Q

Link Aggregation

A

Increases bandwidth between devices by creating one logical link made up of several physical links. Etherchannel is a form of link aggregation.

4
Q

Power over Ethernet (PoE)

A

Allows switch to deliver power to a device over the existing Ethernet cabling

5
Q

Three Categories of Routers

A

Branch, Network Edge, Service provider

6
Q

Branch Routers

A

HIghly available 24/7

7
Q

Network Edge Routers

A

High performance and security, reliable services. Connect campus, data centre, and branch networks

8
Q

Service Provider Routers

A

Ultra high performance and security, reliable services. Connect corporations and ISPs

9
Q

In-Band Management

A

Requires at least one interface to be connected and operational, and the use of Telnet, SSH, HTTP, HTTPS to access the device.

10
Q

Out-of-Band Management

A

Requires direct connection to console or AUX port and Terminal Emulation client to access device.

11
Q

Vlan Trunking Protocol (VTP)

A

Allows network admin to manage VLANs on a VTP-enabled server switch. The VTP server distributes and synchronizes VLAN information over trunk links to VTP-enabled switches throughout the switched network. VTP only learns about normal range VLANs (VLAN IDs 1 to 1005).

12
Q

VTP Components

A

VTP Domain, VTP Advertisements, VTP Modes, VTP Password

13
Q

VTP Modes

A

Server, Client, Transparent

14
Q

VTP Revision Number

A

32-bit number that indicates the level of revision for a VTP packet. Each VTP device tracks the VTP configuration revision number that is assigned to it and compares it to the received revision number. Each time that you make a VLAN change in a VTP device, the configuration revision is incremented by one.

15
Q

VTP Advertisements

A

Summary Advertisements, Advertisement Request, Subset Advertisements

16
Q

VTP Bomb

A

When a VTP switch with higher revision number and existing VLAN configurations is added to an existing VTP domain.

17
Q

How to reset VTP configuration revision number

A

Change the switch’s VTP domain to a nonexistent VTP domain and then change the domain back to the original name. Change the switch’s VTP mode to transparent and then back to previous VTP mode.

18
Q

VTP Configuration Steps

A
  1. Server
  2. Domain name and Password
  3. Clients
  4. VLANs on VTP server
  5. Verify clients have received new VLAN info
19
Q

Normal Range VLANs

A

1 - 1005

20
Q

Extended Range VLANs

A

1006 - 4094

21
Q

Spanning Tree Protocol (STP)

A

Ensures that there is only one logical path between all destinations on the network by intentionally blocking redundant paths that could cause a loop.

22
Q

Types of Spanning Tree Protocols

A

STP, PVST+, RSTP, Rapid PVST+, MSTP

23
Q

Root Bridge

A

Serves as a reference point for all STA calculations. There is only one Root Bridge for each Broadcast Domain The switch with the lowest ‘BID’ automatically becomes the root bridge for the STP calculations.

24
Q

Root Port

A

Switch ports closest to the root bridge in terms of overall cost to the root bridge. Root ports are selected on a per-switch basis.

25
Q

Designated Ports

A

All non-root ports that forward traffic on the network. Designated ports are selected on a per-segment basis. If one end of a segment is a root port, then the other end is a designated port. All ports on the root bridge are designated ports.

26
Q

Alternate Ports

A

Alternate ports are in discarding or blocking state to prevent loops. Alternate ports are selected only on links where neither end is a root port.

27
Q

STP Steps

A
  1. Choose root bridge
  2. Set Root ports
  3. Set port roles
28
Q

Root Bridge Selection Process

A

a) Lowest priority (0-61440) in increments of 4096

b) Lowest mac-address

29
Q

Bridge Protocol Data Unit (BPDU)

A

Used by STP to build and maintain the tree. Sent and received on the Default VLAN

30
Q

BPDU Proccess

A

When adjacent switches receive a BPDU frame, they compare the root ID from the BPDU frame with the local root ID. If the root ID in the BPDU is lower than the local root ID, the switch updates the local root ID and the ID in its BPDU messages. If the local root ID is lower than the root ID received in the BPDU frame, the received BPDU frame is discarded.

31
Q

STP/PVST+ Port States

A

Disabled, Listening, Learning, Forwarding, Blocking

32
Q

Disabled

A

Doesn’t participate in STP operation (it is shut down).

33
Q

Listening

A

Can send and receive BPDU frames. Doesn’t learn any MAC addresses, discards all frames. The STP computation of loop free topology takes place in this state. Duration: 15 seconds

34
Q

Learning

A

STP has run and the port role has been determined. Won’t forward frames yet. It will be learning MAC addresses in order to populate MAC address table. Duration: 15 seconds

35
Q

Forwarding

A

Can forward all frames as per it’s port role.

36
Q

Blocking

A

Doesn’t forward frames, doesn’t accept frames (discards arriving frames), doesn’t learn MAC addresses. Does process BPDU frames received from a neighboring switch.

37
Q

PVST+

A

A network can run an independent STP instance for each VLAN. One spanning-tree instance for each VLAN maintained will mean an increase in CPU cycles for all the switches in the network. Load balancing (per VLAN) can be configured. Additional bandwidth use because each instance sends its own BPDUs. 5 Port states (Same as STP)

38
Q

STP Timers

A

Hello, Forward Delay, Max age

39
Q

Hello

A

The time between each BPDU that is sent on a port. 2 seconds by default, can be tuned between 1 and 10 sec.

40
Q

Forward Delay

A

The time that is spent in the listening and learning states. 15 sec by default for both, can tuned between 4 and 30 sec.

41
Q

Max Age

A

The maximum length of time allowed between BPDUs’ 20 sec by default, can be tuned between 6 and 40 sec. After Max Age timer has counted to 20s, the blocking port transitions to a designated port

42
Q

Direct Failure

A

Is detected immediately and enables a switch to expire the Max Age timer, invalidating all current configuration BPDUs. If the forward delay timer is the standard 15 seconds, the convergence time of a direct failure will be: 30 seconds.

43
Q

Indirect Failure

A

An indirect failure is not detected immediately and relies upon expiration of the Max Age timer. If using the default STP timers, the convergence time of an indirect failure is: 50 seconds.

44
Q

PortFast

A

When a switch port is configured with PortFast that port transitions from blocking to forwarding state immediately.

45
Q

BPDU Guard

A

BPDU guard puts the port in an error-disabled state on receipt of a BPDU.

46
Q

RSTP and Rapid PVST+

A
  • Faster Convergence than STP/PVST+
  • RSTP is the preferred protocol
  • RSTP keeps the same BPDU format as STP, except that the version field is set to 2 to indicate RSTP (backwards compatible).
  • RSTP defines port states as discarding, learning, or forwarding.
  • With Rapid PVST+ an independent instance of RSTP runs for each VLAN.
  • RSTP is able to actively confirm that a port can safely transition to the forwarding state without having to rely on a timer configuration. *
47
Q

Rapid PVST+

A
  • RSTP supports port type: Alternate in Discarding state (There are no blocking ports) If a port has been defined as an “Alternate” it can immediately change to a forwarding state and not wait for the network to converge.
  • Root Bridge elected the same way as with STP/PVST+
  • Ports determined the same way as with STP/PVST+
  • Protocol information can be immediately aged on a port if Hello packets are not received for three consecutive Hello times (six seconds, by default) or if the max age timer expires.
48
Q

Non-Edge Port

A

Port connected to other switch

49
Q

Edge port

A
  • Port that is never intended to connect to another switch
  • Immediately transitions to a forwarding state (no discarding/learning)
  • An edge port that receives a BPDU immediately loses edge port status and becomes a non-edge port
  • Use the “spanning-tree portfast” command to configure edge ports
50
Q

Port Types

A

Edge port, Non-edge port

51
Q

Link Types

A

Point-to-point, Shared

52
Q

Point-to-point

A

A port operating in full-duplex mode typically connects a switch to a switch, it is a candidate for a rapid transition to a forwarding state.

53
Q

Shared

A

A port operating in half-duplex mode connects a switch to a hub that attaches multiple devices.