🪴 Peter Garden

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1736130293-ccna-notes1

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CCNA-Notes

ipv6 free cert + sigma 6 cert + mongodb cert Certified in Cybersecurity Certification | ISC2

Full- Duplex UTP Cables(10base-t),100base-t So remember this, Routers transmit data on pins 1 and 2, and receive data on pins 3 and 4

Once again, switches are the opposite- due to oppisite transfer style , it woks

receive data nnlninq 1 and 2 and transmit = 3 and 6

straight-through cable 1 → 2 2 → 1 3 → 3

router to router → don’t work 1 → 1 due to same traansfer style

switch to switch → don’t work as well

  • UTP cables (10base-t,100 base-t)

Crossover cable, solve this problem 1 → 3 2 → 6 3 → 1 6 → 2

Table: Device Type Transmit (TX) Pins | Receive (RX) Pins

Router 1 and 2 3 and 6 Firewall 1 and 2 3 and 6 PC 1 and 2 3 and & Switch 3 and 6 1 and 2 only switch is different

mordern → AUTO MDI-x , auto deteck and adjust

  • utp cables(1000base-t,10gbase-t)

    • each pair is bidirectional

SFP Transceiver

fiber-optic connections Tx → transmit Rx → Receive

the outer jacket of the cable(differnt breed)

  • single-mode
    • allow longer cables than both utp
  • multimode
    • wider core diameter
    • cheaper

table

UTP cable VS Fiber-optic cable

  • uTpP Lower cost than fiber-optic. Shorter maximum distance than fiber-optic (~100m).

Can be vulnerable to EMI (Eletromagnetic Interference). RJ45 ports used with UTP are cheaper than SFP ports.

Emit (leak) a faint signal outside of the cable, which can be copied (=security risk)

  • Fiber-Optic Higher cost than UTP. Longer maximum distance than UTP. No vulnerability to EMI. SFP ports are more expensive than RJ4S ports (single-mode is more expensive than multimode). Does not emit any signal outside of the cable (=no security risk).

optical fiber is actually cover longer distance than utp

single-mode is the longest

  • cover 3 km 🐂

utp → muitleple switch

Layer 2

the minimum payload size for ethernet frame is 46 bit

Ethernet Frame → APR ICMP → (Ping)

show mac adderss table clear mac address table address clear mac address table intrface

ping

cisco need to enable root mode first

ping → show the size 36

need 10 byte to fullfill the minimum 46-36=10

padding byte to fullfill that

Padding : 10 bytes of padding hex → 20 0 ,(two 0 of hex 0x0 =1 bytes) → 20/2 = 10 bytes

wireshark →

Type → (0x0800) IPvl 4 Type0x86dd → IPv6

e.g. → APR(0x0806) → inside the frame

ARP ( address resolution protocol)

  • ARP request (broadcast all hosts on the LAN ( local network))
  • arp reply

ARP table

  • ping
    • ICMP echo request
    • ICMP echo Reply
  • MAC address Table

show mac address-table cisco show what ? vlan | mac address | type | ports

arp -a 🗝️

internet | physical address|type

  • which types of frames does a switch send out of all iterfaces, except the one the frame was received on?
    • Broadcast, unkown unicast FFFF.FFFF.FFFF.FFFF.FFFF only unknown unicast require broadcast

How to clear all dynamic Mac addresses ? clear mac address-table dynamic

Clear all entries for a specific dynamic MAC address from the MAC Address Table:

  • clear mac address-table dynamic address mac-address

what is the ethernet type code for an ARP packet?

  • 0x0806

What is the minimum size of an Ethernet frame? (Header + Payload + Trailer) 64 bytes

  • minimum size of an Ethernet payload/packet ⇒ 64 bytes – 18 bytes (header + trailer size) = 46 bytes

Command to show the arp table on a cisco deice

  • show arp

Graph View

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