Network+ N10-009 2.0 Network Implementation

Static routing

• Manual method of forwarding traffic where paths must be configured by an administrator

• Manually making a routing table

• Good for small networks

• No overhead for routing protocols like DHCP

• If there’s a network change, you have to manually update it every time

Dynamic routing

• Automatic method of forwarding traffic that adapts to network changes using routing protocols

• New routes are populated automatically

• Some router overhead that takes CPU, memory, and bandwidth

• Requires initial configs

Dynamic routing(Border Gateway Protocol (BGP))

• Exterior gateway protocol that exchanges routing information between autonomous systems on the internet

• Used on WANs for communication across the internet

Dynamic routing(Enhanced Interior Gateway Routing Protocol (EIGRP))

• Cisco proprietary protocol that uses multiple metrics to select efficient paths within a network

• Does not have to be used only on cisco-centric networks

• Easy to use and enable

• Cleanly manage topology changes

• Loop free operation

• Good at minimizing bandwidth usage

Dynamic routing(Open Shortest Path First (OSPF))

• Link-state protocol that calculates the shortest path using a map of the network topology

• Used within a single autonomous system (AS)

• Available on many router models from many manufacturers

• Routing is based on “cost” which is determined by the uptime of other OSPF routers as well as the throughput and round-trip time

  • Identical costs are load balanced

Routing table format:

R 10.10.30.0/24 [120/1] via 10.10.50.2, 00:00:14, Serial0/3/1

• R = route code (R is an example)

• 10.10.30.0/24 = Dest Subnet ID with prefix length

• 120 = Administrative distance

• 1 = Metric

• via 10.10.50.2 = next hop

• 00:00:14 = route timestamp (how long this route has been active inside the routing table)

• Serial0/3/1 = outgoing interface

Route selection(Administrative distance)

• Value that ranks how trustworthy a routing source is, with lower values preferred

• If you have two routing protocols that both know about a route to a subnet, which one do you trust the most?

• These are static values, listed in the table (image)

Route selection(Prefix length)

• Measurement of route specificity where longer matches are chosen over shorter ones

• Routes are more specific as the prefix increases

• /24 would beat /16

Route selection(Metric)

• Numeric value assigned by a protocol to determine the best path among multiple options

• These metrics are not useful to different routing protocols

Address translation(NAT)

• Process of mapping private IP addresses to public addresses for external communication

• One private address converts to a public IP address that can talk to external IPs and the reverse happens when communicating back to the internal network

Address translation(Port address translation (PAT))

• Variation of NAT that allows many devices to share one public IP by using port numbers

• Also called NAT overload

• Allows for many devices to use 1 public IP address

First Hop Redundancy Protocol (FHRP)

• Technology that provides gateway failover by assigning a shared address to multiple routers

• The default router IP address isn’t real

  • Devices use a virtual IP (VIP) for the default gateway

  • If a router disappears, another one takes its place

Virtual IP (VIP)

• IP address not tied to a single device, often used for redundancy or load balancing

Subinterfaces

• Logical partitions of a single physical interface used to separate traffic for VLANs or subnets

Virtual Local Area Network (VLAN)

• Logical segmentation of a network into separate broadcast domains on the same physical hardware

• VLANs are configured by number, eg: F0/1, F0/2

VLAN Trunk

• If you have multiple VLANs on one switch and the same VLANs on another switch, you would need one ethernet cable connected between each switch per VLAN

• This allows you to configure an ethernet cable to allow all VLAN traffic to communicate across it while still maintaining the separation of the VLANs

• It does this by doing 802.1Q tagging

VLAN database

• Central storage of VLAN configuration information on a switch

Switch Virtual Interface (SVI)

• Logical interface on a switch used for management or inter-VLAN routing

Interface configuration(Native VLAN)

• Default VLAN assigned to untagged traffic on a trunk port

• Can still communicate over a trunk

  • No VLAN tag is added to traffic

• Needed for devices that can’t talk over 802.1 networks

• Need to be identical between devices

Interface configuration(Voice VLAN)

• Special VLAN designed to prioritize VoIP traffic on a network

• Voice and data don’t like each other

• Voice is sensitive to congestion

• Separating these VLANs and using a trunk eliminates this issue

• Each interface has multiple VLANs

Interface configuration(802.1Q tagging)

• Standard method of marking Ethernet frames with VLAN IDs for trunking

• Goes after the source mac address

• 12 bits long, up to 4094 VLANs

Interface configuration(Link aggregation)

• Combining multiple network interfaces to increase bandwidth and provide redundancy

• Multiple interfaces act as one big interface

  • Will not create loops

• LACP (Link Aggregation Control Protocol)

Interface configuration(Speed)

• Setting that controls the data rate of a network connection

• 10/100/1000/10G

  • Needs to be the same on client and switch or it won’t work at all

  • Often automatic, switch will adjust based on client’s choice

Interface configuration(Duplex)

• Setting that determines whether communication is one-way at a time or simultaneous both ways

• Needs to match on both sides

  • Will still work, but very slowly

Spanning tree

• Protocol that prevents switching loops by disabling redundant paths

• 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

• Modern version is Rapid STP (802.1w)

  • 6 seconds convergence process

  • Backwards compatible with STP

Maximum transmission unit (MTU)

• Largest size of a packet that can be transmitted without fragmentation

• Hard to find out which network would need fragmenting because of firewalls and filtering, etc

Maximum transmission unit (Jumbo frames)

• Packets larger than the standard 1500 bytes used to improve efficiency on some networks

• Up to 9216 bytes

• Fewer packets to route

• All devices on path must understand this kind of frame

Channels

• Frequency ranges used by wireless networks for communication

• Easier than saying the specific frequency that a wireless device communicates over

Channels(Channel width)

• Measurement of the bandwidth of a wireless channel in MHz

• 20, 40, 80, 160 MHz

Channels(Non-overlapping channels)

• Wireless frequencies spaced apart to avoid interference

Channels(Regulatory impacts)

• Restrictions on wireless frequencies and power levels imposed by local laws

Channels(802.11h)

• Standard that adjusts frequency and power in the 5 GHz band to avoid interference with radar

• DFS (Dynamic Frequency Selection)

  • Avoid frequency conflict

  • Access point can switch to an unused frequency

  • Clients move with the access point

• TPC (Transmit Power Control)

  • Avoid conflict with satellite services

  • Access point determines power output of the client

Frequency options(2.4GHz)

• Wireless band with longer range but more interference and fewer channels

Frequency options(5GHz)

• Wireless band with higher throughput and more channels but shorter range

Frequency options(6GHz)

• Newest Wi-Fi band offering wider channels and less interference

Frequency options(Band steering)

• Technique that pushes dual-band clients to use the less congested 5 GHz or 6 GHz band

Service set identifier (SSID)

• Name assigned to a wireless network that clients use to connect

• Multiple access points can have the same one

Service set identifier (BSSID)

• Unique identifier tied to the MAC address of a specific access point

Service set identifier (ESSID)

• Name representing a group of access points forming one extended network

Network types(Mesh networks)

• Wireless design where nodes connect to each other to provide redundancy and coverage

• Multiple access points that all communicate with each other with devices connected to them

Network types(Ad hoc)

• Peer-to-peer wireless connection between devices without an access point

• Uses IBSS (Independent basic service set)

• Communicate using 802.11 directly to each other

• Short term connections can include passing config and network information to a IoT device

Network types(Point to point)

• Extend a wired network over a distance wirelessly

• Building-to-building, site-to-site, etc

• Requires specialized hardware and proper configurations

Network types(Infrastructure)

• Wireless setup where clients connect through access points to the wired network

• Found in most homes and offices

Encryption(Wi-Fi Protected Access 2 (WPA2))

• Wireless encryption standard using AES for strong security

Encryption(WPA3)

• Latest wireless encryption standard with improved protection and forward secrecy

Guest networks

• Separate wireless network that isolates visitor traffic from internal resources

Guest networks(Captive portals)

• Web page that requires user interaction before granting network access

• Your device can be added to an access table to allow you to be able to automatically connect for a set period of time

Authentication(Pre-shared key (PSK) vs. Enterprise)

• PSK - Password-based wireless security. One password to rule them all

• E - Centralized authentication via RADIUS or LDAP

Antennas(Omnidirectional vs. directional)

• Difference between antennas that broadcast in all directions versus focused coverage

• Directional can go farther

Autonomous vs. lightweight access point

• Standalone APs manage themselves, while lightweight APs rely on a central controller

• AAPs handle most wireless tasks and is not wireless-aware

• LAPs are just enough to be 802.11 wireless

• LAPS give us control and provision

  • CAPWAP (Control and Provisioning of Wireless Access Points)

  • Lets you manage multiple access point simultaneously

Important installation implications(Locations)

• Placement of networking equipment impacts performance, accessibility, and cabling

• For example, an access point with a omnidirectional antenna placed in the corner of the room is not very effective because half of the signal power is wasted

Important installation implications(Intermediate distribution frame (IDF))

• Telecom room that connects local equipment to the main distribution frame

• Smaller version of the MDF

• Switches and routers meant to communicate the LAN to the MDF and subsequently, the WAN

Important installation implications(Main distribution frame (MDF))

• Central location housing core network connections and often WAN access

• Central point of network

  • Usually in a data center

• Bring in WAN connections and LAN connections here

Important installation implications(Rack size)

• Standardized dimensions of equipment racks used for mounting networking gear

• 19” rack in width

• Rack Units apply to height as well and are standardized

  • Measured in Us

  • 1U is 1.75”

  • a common rack height is 42U

• Depth of racks and equipment can vary

Important installation implications(Port-side exhaust/intake)

• Airflow direction of rack equipment affecting cooling design

• HVAC is complex. It needs powers, integration into fire system, and cools our center enough

• Data centers optimize cooling and have separate aisles for heating and cooling

• Make sure equipment is blowing hot air to the hot aisle and cool air is being pulled back into the data center

Important installation implications(Cabling)

• Wiring infrastructure that connects network devices together

• Wires go from end devices to an IDF (patch panel) which has switches that allow for easy connection configuration

Important installation implications(Patch panel)

• Interface that organizes and connects incoming and outgoing network cables

• Easy to move connections around

Important installation implications(Fiber distribution panel)

• Central termination point for fiber optic cabling

• Patch panel of fiber

• Don’t exceed fiber bend radius

• Contains a service loop

Important installation implications(Lockable)

• Security measure to restrict physical access to network equipment

• Allows for extra security

• Still allows for ventialtion

Power(Uninterruptible power supply (UPS))

• Backup device that provides short-term power during outages

Power(Power distribution unit (PDU))

• Device that distributes electrical power to multiple pieces of equipment in a rack

• Smarter than a surge protector. Can be remoted into to control

Power(Power load)

• Amount of electrical power consumed by connected devices

Power(Voltage)

• Electrical potential difference supplied to networking equipment

• “Pressure” of electricity, pressure pushing electrons

Power(Amps)

• The rate of electrons that are flowing past a point

Power(Watts)

• Number of volts * number of amps

• How much energy is being consumed

Power(Current)

• AC - direction of current constantly reverses

  • Good for long distances

  • Frequency in US is 110-120 volts at 60 Hz

  • Frequency in EU is 220-240 volts at 50 Hz

• DC - power moves in direction with constant amount of voltage

Environmental factors(Humidity)

• Moisture levels in the air that can damage electronics if too high or too low

• High humidity = condensation

• Low humidity = static discharge

• Somewhere from 40-60% is the sweet spot

Environmental factors(Fire suppression)

• Systems designed to detect and extinguish fires in server rooms and data centers

• Using inert gas or chemical agent in data center is better than water

• HVAC gets shut off when fire alarm is triggered to stop oxygen

Environmental factors(Temperature)

• Heat levels that must be controlled to prevent hardware failure

• 64-81 degrees is sweet spot