Layer 2 + Layer 3 Flashcards
records the source MAC address, port & VLAN, and timestamp of each received frame. The maximum default time an entry will be kept on the table is 300 seconds.
CAM Table
a specialized CAM designed for rapid table lookups. provides three results: 0, 1, and “don’t care.” is most useful for building tables for searching on longest matches such as IP routing tables organized by IP prefixes.
TCAM
is where all IP Routing information is stored. It is not specific to any routing protocol, rather a repository where all the routing protocols place all of their routes.
Routing Information Base
refers to the process by which the router’s CPU or processor is directly involved in the forwarding decision.
Process Switching
It is actually a reactive cache-based IP forwarding mechanism i.e. the address lookup uses a route cache to find the IP next-hop, outgoing interface, and outbound layer-2 header. Destination addresses are stored in the high-speed cache to expedite forwardin
Fast Switching
switching is a proprietary form of scalable switching intended to tackle the problems associated with demand caching. the information which is conventionally stored in a route cache is split up over several data structures.
Cisco Express Forwarding (CEF)
is a technology with which we can create separate virtual routers on a physical route. With these separate virtual routers, we can use router interfaces, routing and forwarding tables isolated with this.
Virtual Routing and Forwarding (VRF)
provides a virtual point-to-point private connection and encapsulates and forwards packets over an IP-based network
GRE (Generic Routing Encapsulation)
occurs when the router learns the destination IP address for the tunnel interface through the tunnel itself. It removes the previous entry for the tunnel destination IP address from the routing table, making the tunnel’s destination inaccessible
Recursive Routing
IP Sec Components
Authentication
Integrity
Confidentiality
a key management protocol standard that is used in conjunction with the IP Security (IPSec) standard. IPSec is a feature that provides robust authentication and encryption of IP packets.
IKE (Internet Key Exchange)
is a trunking protocol that is developed and proprietary to Cisco which is used to automatically negotiate trunks between Cisco switche
DTP (Dynamic Trunking Protocol)
DTP Modes
auto - passively waits
desirable - initiate trunking
nonegotiate - off
in networking is an IEEE standard and a part of the IEEE 802.3ad specification that allows you to combine multiple network connections or physical links in our network devices to form a single logical link and enable load balancing in our interfaces.
Link Aggregation Control Protocol (LACP)
LACP Configurations Mode
Active
Passive
PagP Configuration Mode
Auto
Desirable
STP - Ports that are forwarding towards the root
Root Ports
STP - Ports that are forwarding away from the root
Designated Ports
Root Bridge Election
- Lowest Bridge Priority
- Lowest Mac address
Root Port Election
- Lowest accumulated cost on interfaces towards Root Bridge
- Lowest Sender Bridge ID
- Lowest Sender Port ID
Designated Port Election
1) Root path cost
2) Bridge ID
3) Sender Port ID
Cisco specific feature that improves the convergence time of the Spanning-Tree Protocol (STP) in the event of the failure of an uplink.
Uplinkfast
enables fast reconvergence due to indirect link failures. The key operation happens when a switch begins receiving inferior BPDUs. When a switch loses the link off its Root Port, it immediately starts sending BPDUs announcing itself as the new Root.
Backbonefast
feature that can be enabled on a port to bypass the normal STP initialization process for that port. When enabled on a port, STP will consider the port to be a “designated port” immediately without going through the normal listening and learning states.29 Jan 2023
Portfast
allows control of spanning tree participation on a per-port basis. It can be used to exclude specific ports from becoming part of spanning tree operations
BPDU Filter
an STP feature that is enabled on a port-by-port basis; it prevents a configured port from becoming a root port. Root guard prevents a downstream switch (often misconfigured or rogue) from becoming a root bridge in a topology.
Root guard
is a safety mechanism that shuts down ports configured with STP portfast upon receipt of a BPDU. Assuming that all access ports have portfast enabled, this ensures that a loop cannot accidentally be created if an unauthorized switch is added to a topology
BPDU Guard
an enhancement that provide protection from the creation of a loop at layer 2. It relies on the receipt of BPDUs. If no BPDUs are received on a blocked port, it is not allowed to transition to the forwarding state. This prevents a loop from occurring
BPDU Loop Guard
allows you to build multiple spanning trees over trunks. You can group and associate VLANs to spanning tree instances. Each instance can have a topology independent of other spanning tree instances. This architecture provides multiple forwarding paths for data traffic and enables load balancing.
Multiple Spanning Tree
Things need to match on spanning tree MST
MST configuration name.
MST configuration revision number.
MST instance to VLAN mapping table.
