CCNP Encore Flashcards by Vusal Askerli

Layer 2 və Layer 3 fərqi

Layer 2 forwarding: MAC adreslər əsasında çərçivələrin (frames) ötürülməsi.

Layer 3 forwarding: IP ünvanları əsasında paketlərin yönləndirilməsi.

How well did you know this?

Not at all

Perfectly

Collision və Broadcast Domains

Collision domain: eyni media üzərində eyni anda ötürmə cəhdi olan cihaz qrupu (hub ilə paylaşılır).

Switch collision domain-i kiçildir, router isə broadcast domain-i bölür.

Broadcast domain: eyni Layer 2 seqmentdəki bütün cihazlar eyni broadcast mesajı alır.

How well did you know this?

Not at all

Perfectly

MAC Address Table (CAM Table)

Switch MAC ünvanları və portları yadda saxlayır.

show mac address-table ilə baxılır.

Unknown unicast → ünvan tapılmayanda switch bütün portlara flood edir.

MAC məlumatları CAM (Content Addressable Memory) içində saxlanılır.

How well did you know this?

Not at all

Perfectly

VLAN əsasları

VLAN – eyni fiziki switch üzərində müxtəlif broadcast domainlər yaradır.

VLAN ID: 1–1005 (normal), 1006–4094 (extended).

VLAN 1 — default, amma təhlükəsizlik baxımından istifadə edilməməlidir.

VLAN yaratmaq:

switch(config)# vlan 10
switch(config-vlan)# name HR

How well did you know this?

Not at all

Perfectly

Access və Trunk portlar

Access port: yalnız 1 VLAN-ı daşıyır (untagged).

Trunk port: bir neçə VLAN-ı daşıyır, 802.1Q tag istifadə olunur.

Native VLAN: Trunk üzərindən keçən untagged traffic üçün VLAN (default = 1, dəyişmək tövsiyə olunur).

How well did you know this?

Not at all

Perfectly

ARP və Yerli Forwarding

ARP (Address Resolution Protocol): IP → MAC xəritələməsi.

Eyni subnetdəki cihazlar birbaşa Layer 2 ilə ünsiyyət qurur.

Fərqli subnet üçün routerə yönləndirilir (default gateway vasitəsilə).

How well did you know this?

Not at all

Perfectly

Routing və Packet Forwarding

Router IP header-i oxuyur və növbəti hop ünvanını müəyyən edir.

Layer 2 frame yenidən yazılır (source/destination MAC dəyişir).

Layer 3 TTL (Time-To-Live) hər hop-da 1 azalır.

How well did you know this?

Not at all

Perfectly

Cisco Express Forwarding (CEF)

Cisco-nun hardware-based forwarding texnologiyasıdır.

İki əsas cədvəl:

FIB (Forwarding Information Base): Routing məlumatlarını saxlayır.

Adjacency Table: MAC ünvanlarını və interfeysləri saxlayır.

CEF prosessor yükünü azaldır, performansı artırır.

How well did you know this?

Not at all

Perfectly

TCAM (Ternary CAM)

3 nəticə: 0 (false), 1 (true), X (don’t care).

ACL, QoS və yönləndirmə qaydalarının hardware səviyyəsində emalı üçün istifadə olunur.

How well did you know this?

Not at all

Perfectly

Forwarding Architecture növləri

Növ İzah
Process Switching CPU hər paketi ayrıca yönləndirir – çox yavaşdır.
CEF (Cisco Express Forwarding) Ən sürətli, default mexanizm.
Centralized Forwarding Yalnız Route Processor qərar verir.
Distributed Forwarding Hər line card öz forwarding qərarını verir.

How well did you know this?

Not at all

Perfectly

Layer 2 Forwarding Concepts

Switch learns source MAC addresses → builds MAC table.

For unknown destination → unknown unicast flooding.

Broadcast MAC FF:FF:FF:FF:FF:FF floods to all ports (same VLAN).

Switch = multiple collision domains, one broadcast domain per VLAN.

Commands:

show mac address-table

clear mac address-table dynamic

How well did you know this?

Not at all

Perfectly

Collision Domains

One device transmits at a time in same segment.

Hub: single collision domain.

Switch: each port = separate collision domain.

Router: breaks broadcast domains.

How well did you know this?

Not at all

Perfectly

Broadcast Domains

All devices receiving Layer 2 broadcasts.

Broadcasts don’t cross Layer 3 boundaries.

Each VLAN = one broadcast domain.

How well did you know this?

Not at all

Perfectly

VLAN Essentials

IEEE 802.1Q adds 4-byte tag:

TPID (0x8100)

PCP (Priority 3 bits)

DEI (1 bit)

VLAN ID (12 bits → 0-4095)

VLAN ID Ranges:

1 (Default) – avoid for data.

2–1001 (Normal range).

1002–1005 (Reserved).

1006–4094 (Extended range)

How well did you know this?

Not at all

Perfectly

Access vs Trunk Ports

Type Function Command
Access One VLAN only; no tags. switchport mode access
switchport access vlan 10
Trunk Multiple VLANs; 802.1Q tagged. switchport mode trunk
switchport trunk allowed vlan 1,10,20
Native VLAN Carries untagged frames (default = 1). switchport trunk native vlan 99

Best practice: change native VLAN from 1 → unused VLAN.

Verify Trunk: show interfaces trunk.

How well did you know this?

Not at all

Perfectly

Layer 2 Diagnostics

Study These Flashcards

show mac address-table [vlan x | address xx]

show interfaces switchport

show interfaces status

Layer 3 Forwarding Basics

Study These Flashcards

Local Forwarding: ARP maps IP → MAC; stays in same subnet.

Remote Forwarding: needs routing (default gateway).

ARP commands: show ip arp, clear ip arp.

Packet process:

Source checks destination IP network.

Finds next-hop MAC (via ARP).

Sends to router.

Router rewrites MAC (header rewrite), decrements TTL, recalculates checksum.

IP Address Assignment

Study These Flashcards

IPv4: ip address 10.1.1.1 255.255.255.0

IPv6: ipv6 address 2001:db8::1/64

Secondary IPv4: ip address 172.16.1.1 255.255.255.0 secondary

Show IPs: show ip interface brief, show ipv6 interface brief.

Subinterfaces & SVIs

Study These Flashcards

Router Subinterface (Router-on-a-Stick):

interface G0/0.10
encapsulation dot1Q 10
ip address 10.10.10.1 255.255.255.0

SVI (Switched Virtual Interface): VLAN-based L3 interface.

interface vlan 10
ip address 10.10.10.1 255.255.255.0
no shutdown

SVI up only if at least one access port in that VLAN is active.

Routed Switch Ports

Study These Flashcards

Converts Layer 2 port to Layer 3:

interface gi1/0/14
no switchport
ip address 10.20.20.1 255.255.255.0

Used for point-to-point routing links between switches.

Forwarding Architectures

Study These Flashcards

Process Switching CPU handles every packet (slow).
Fast Switching Cache based (old).
CEF (Cisco Express Forwarding) Uses FIB & Adjacency Table for fast, deterministic forwarding (default).
Centralized Forwarding One CPU (Route Processor) does forwarding decisions.
Distributed Forwarding Each line card has local ASIC / NPU forwarding.

Cisco Express Forwarding (CEF)

Study These Flashcards

FIB (Forwarding Information Base): built from routing table (RIB).

Adjacency Table (AIB): next-hop MAC & interface info from ARP.

Glean Adjacency: incomplete entry → CPU processing.

CEF Benefits:

Deterministic & hardware-based.

Fast reroute support.

Reduces CPU load.

Ternary Content Addressable Memory (TCAM)

Study These Flashcards

Performs parallel matches → result = 0 (true), 1 (false), X (don’t care).

Used for ACLs, QoS, Routing lookups.

VMR format: Value, Mask, Result.

Multiple TCAMs allow security, QoS, and L3 decisions in hardware.

Software CEF vs Hardware CEF

Study These Flashcards

Type Description
Software CEF Performed by CPU. FIB + Adjacency Tables in RAM.
Hardware CEF Performed in ASICs/NPUs for line-rate forwarding.
dCEF (Distributed CEF) Line cards contain local FIB/AIB copies.

SDM Templates (Switching Database Manager)

Defines how TCAM memory is divided (L2 vs L3 vs QoS vs Security). Common templates: sdm prefer vlan – for Layer 2 networks. sdm prefer advanced – for L3/routing features. Apply & reload switch after changing. Verify: show sdm prefer.

Quick Tips for Exam

Default MAC aging time: 300 s. Default Forward delay: 15 s. Native VLAN mismatch triggers CDP warnings. CEF = default switching mechanism on modern Cisco devices. ARP table populated dynamically via broadcasts. CAM → L2, TCAM → L3/ACL/QoS functions.

CCNP Encore Flashcards

(26 cards)