Midterm Flashcards
Network Characteristics
Topology, Speed, Cost, Security, Availability, Scalability, Reliability
Components of a Network Capable Device
CPU, Operating System, Memory and Storage
Process Switching
Packets are forwarded to the control panel where the CPU decides where to forward the packet
Fast Switching
A fast switching cache is used to store next-hop information. If a packet is going to a destination with info in the cache the next-hop info in the cache is used without CPU intervention
Cisco Express Forwarding (CEF)
CEF uses a Forwarding Information Base that is change-triggered. It is the fastest forwarding method and preferred choice on Cisco routers
Best Path
Selected by a routing protocol based on the value/metric it uses to determine the distance to reach a network. It is the path with the lowest metric
Metric
Value used to measure distance to a network
Dynamic routing protocol metrics
RIP - hop count
OSPF - Cost (cumulative bandwidth fr source to dest.)
EIGRP - Bandwidth, delay, load, reliability
Load Balancing
When a router has two or more paths with equal cost metrics, packets are forwarded using all paths equally
Administrative Distance
If multiple paths to the same dest. are configured on the same router, the one in the route table is the one with the lowest AD. The lower AD, the more reliable
Routing Table
Stored in RAM, contains info about direct connected and remote routes
What does OSPF stand for?
Open Shortest Path First
What does EIGRP stand for?
Enhanced Interior Gateway Routing Protocol
What does RIP stand for?
Routing Information Protocol
What does IS-IS stand for?
Intermediate System-to-Intermediate System
IPv6 Dynamic Routing Protocols
OSPFv3, RIPng (next gen), EIGRP for IPv6
IPv6 Static Route Next Hop Options
Next hop: only ip specified
Direct: only exit interface specified
Fully specified: ip and exit interface specified
IGP
Interior gateway protocol: routing within an AS; includes RIP, OSPF, IS-IS
EGP
Exterior gateway protocol: routing between AS; BGP is the official protocol used by internet
Distance Vector Routing Protocols
Use distance (hop count/#of routers) and direction (which interface)
Link-State Routing Protocols
Use sophisticated algorithm (SPF) and simple metrics (bandwidth) to calculate best path
Why passive interfaces?
Because unneeded updates are waste of bandwidth, resources and security risk
How to propagate a default route?
default-information originate
Routes are discussed in terms of?
Ultimate, level 1, level 1 parent, level 2 child
Ultimate Route
Contains either next-hop ip or exit interface
Level 1 Route
Subnet mask is equal to or less than the classful mask of the net address (eg. network, supernet/summary, default)
IPv6 Route Table Entries
All routes are level 1 ultimate routes
Converged network elements
Multiple types of traffic only one network, savings on installation and management, integrates IT management
Cisco Borderless Networks
Allows organizations to connect anyone, anywhere, anytime, any device, securely, reliably and seamlessly
Borderless Switched Network designs built on what principles?
Hierarchical, modularity, resiliency, flexibility
Switched Network Form Factors?
Fixed, stackable, modular
Multilayer Switching
Deployed in core and distribution layers, can build route table, supports few routing protocols, forwards ip packets, supports multiple SVIs
Switch Boot Sequence
- POST
- Run boot loader software (small program in ROM)
- Boot loader performs low-level CPU initialization
- Boot loader initializes flash file system
- Boot loader locates and loads a default IOS software image into memory and passes control of switch to IOS
Where are configuration files stored on a switch?
NVRAM
How to use boot loader to manage switch?
- Connect by console cable and unplug power cord
- Reconnect power cord and hold Mode button
- Wait for the System LED to turn amber and then green. Release the Mode button. Boot loader prompt in terminal is Switch:
Cisco Catalyst 2960 switch modes
System, Redundant power system (RPS), Port status, Port duplex, Port Speed, Power over Ethernet (PoE)
Duplex Communication
Full duplex: send and receive
Half duplex: send or receive
Auto-MDIX
Certain cable types were required when connecting devices, the auto medium-dependent interface crossover feature eliminates this problem. When auto-MDIX is enabled, interface auto detects and configures the connection. When using auto-MDIX on an interface, the interface speed and duplex must be auto.
3 Port Security Violation Modes
Protect: no notification
Restrict: notification received
Shutdown
Normal Range VLANs and Extended Range VLANs
Normal range: 1 to 1005 (1002-1005 for legacy VLANs)
Extended range: 1006 to 4096
What is an ACL?
A series of IOS commands that control whether a router forwards or drops packets based on info from the packet header
ACEs
Access control entries (ACL statements)
Wildcard Mask
a string of 32 binary digits used by router to determine which bits of address to examine for a match
Extended ACLs
Configure as close to source as possible
Standard ALCs
Configure as close to destination as possible
Four Step Process to Obtain a Lease
- DHCP Discover
- DHCP Offer
- DHCP Request
- DHCP Acknowledgement
Two Step Process to Renew a Lease
- DHCP Request
2. DHCP Acknowledgement
SLAAC
Stateless Address Auto Configuration. Uses router solicitation (RS) and router advertisement (RA) messages to provide addressing and other configuration information
Duplicate Address Detection
Send a Neighbor Solicitation message to an IPv6 address and wait for a response to check if address is in use
What is NAT?
Used to translate private IP addresses to public addresses, hides internal addresses from outside networks
PAT
Port Address Translation (NAT overload), can use one public IPv4 address to allow thousand of private IPv4 addresses to communicate with outside network devices. Uses port numbers to track the session
CDP
Cisco Discovery Protocol, layer 2 protocol used to gather info about Cisco devices sharing a link: type of device, name, number and type of interfaces
LLDP
Link Layer Discovery Protocol, vendor neutral neighbor discovery like CDP, works with routers, switches, wireless LAN access points. Advertises identity and capabilities to other devices and info from connected layer 2 devices
NTP
Network Time Protocol: uses UDP port 123, obtain time and date from single source
NTP Operation
Stratum 0: top level of hierarchical system, authoritative time sources, assumed to be accurate
Stratum 1: directly connected to authoritative sources and act as primary network time standard
Stratum 2 and Lower: connected to stratum 1 devices via network connections, act as servers for stratum 3 devices
Smaller stratum numbers: closer to authoritative time source
Larger stratum number: lower stratum level (max hop is 15)
Stratum 16: lowest stratum level, indicates device is unsynchronized
Syslog
Describes a standard and protocol. UDP port 514. Provides ability to gather logging info for monitoring and troubleshooting, select type of logging info, specify destinations of captured messages
Syslog Message Destinations
Logging buffer (RAM), console line, terminal line, Syslog server
