CCNA Small but usefull Notes…

TCP Header 20-bytes without options 😀

UDP Header 8-bytes 😀

Ethernet Header 20 bytes

Frame Relay  Header 4-6 bytes

Point-to-Point Header 6 bytes

IP Header 20 bytes

EGP Protocols -like BGP- are used between AS

Neighbor table & Topology table in EIGRP are kept in RAM

Inverse ARP maps DLCI to IP

In MAC address the 1st 3-Bytes (24-bits) are the OUI (Organizationally Unique Identifier)

The Command #show ip ospf interface …. gives you the hello timer

Routing table Samples   R=Rip ,  I=IGRP , D=EIGRP , O=OSPF , C=Connected Directly , S=Static Route

In OSPF, DR collects & distributes the routing updates then sends them through Multicast address 224.0.0.5 to Non-DR routers

Non-DR routers send updates to 224.0.0.6 to the DR

All OSPF routers (DR & Non-DR) send hello using 224.0.0.5

OSPF sends hello every 10 secs and the dead time is 4 x hello = 4 x 1- = 40 secs

EIGRP sends hello every 5 secs (every60 seconds on WAN links) and the dead time is 3 x hello = 3 x 5 = 15 secs

EIGRP uses Multicast address 224.0.0.10 to send updates and hellos

EIGRP use DUAL to determine loopfree paths

EIGRP uses RTP to ensure reliable delivery of updates and uses seq. number to ensure order

EIGRP does not use TCP or UDP, instead it uses RTP

RIP broadcast every 30 secs and uses multicast address 224.0.0.9

IGRP broadcast routing table every 90 secs

TCP Ports  Telnet 23, FTP 20, 21  , DNS 53, HTTP 80, HTTPS 443, SMTP 25

UDP Ports DNS 53, SNMP 161, TFTP 69

802.1D   STP

802.1W   RSTP

802.1Q    Trunk

802.1ad   LACP

802.1p   QoS

That’s enough for now i’ll continue soon, hope to see some comments to encourage me to finish it fast 😀

If there are mistakes or any questions plz say..

~ by Network Techs. on September 1, 2009.