Archive for the COLD Memory Items Category

Cold Memory Items To Have down COLD!!!!!!!!!!

Posted in COLD Memory Items on July 20, 2008 by itdaddy

this is what I have seen.

Subnets = 2^n – 2
Hosts = 2^n – 2

ip subnet-zero /applied global config mode

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Subnets = 2^n /changes it to this so all 0s and all 1s can be used as ip addresses
Hosts = 2^n – 2

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Cold Memory
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wireless
802.11 IEEE

802.11a – 25 MBps – 54 MBps, indoor range 100 feet 5 Ghz

802.11b – 6.5 MBps – 11 MBps, 100 feet indoor range, 2.4 Ghz

802.11g – 25 MBps – 54 MBps, indoor 100 feet, 2.4 Ghz comapt with  802.11b

802.11n – 200 MBps – 540 MBps indoor 160 feet, 2.4 Ghz or 5 Ghz

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OSPF costs:

56 kbps             = 1788
T1 1.544 MBps = 64
Ethernet             = 10

cost OSPF link = 107/bandwidth (bps) bandwidth 128 (128kbps = 128000)

781 = 10^7/128000

 64 = 10^7/1544000

 

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IEEE

802.1w  RSTP
802.1d  STP
802.1q  trunking(tagging)
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Troubleshooting commdands (cisco, windows)

windows:

ipconfig /all
ipconfig /release
ipconfig /renew

pathping
ping
tracert

cisco:

traceroute

ping <cr> extended ping
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show cdp
send cdp 60 seconds
holdtime cdp 180 seconds
send cdpv2 enable
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subnetting memory
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Private IP addresses:

10.0.0.0      – 10.255.255.255 /8
172.16.0.0    – 172.31.255.255 /12
192.168.0.0   – 192.168.255.255 /16
168.254.0.0   – 168.254.255.255 /16
Classful Ip addresses:

A 1 – 126   /8    127 loopback PCs
B 128 – 191 /16
C 192-223   /24
D 224       /32 mulicast
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Base 2 memory
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note: what I try to do is memorize some and the pattern.
So I can regenerate the pattern without having to memory everything.
2^5 = 32
2^6 = 64  (double)
2^7 = 128 (double….)
2^8 = 256
2^9 = 512
2^10= 1024
you get the idea
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Hex Table converter
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hext is base 16^n
A-F = 10 – 15 numerically
0-9 = 0 – 9 numerically
example: link-local address prefix: FE08

conert FE to hex and 08 to hex.

256   16    1
————–
       F    E  = F=15+ E=14 = 15+14=29
       0    8  = 0=0 + 8 =8   0 + 8 = 8

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IPv6 facts:
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Global Unicast – scope global public
site-local  – private site lan
link-local  FE80::  same subnect node MAC
loopback    ::1
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types of casts:
——————

unicast    – packet to one interface
multicast  – packet to many interfaces
anycast    – packet nearest multiple interfaces

**no more broadcasts**
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switch spee cost
———————————————–
10  MBps   = 100
100 MBps   = 19
1   GBps   = 4
10  GBps   = 2

 

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OSI Model memory:
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Click on picture below to enlarge into IE7 Explorer. 

 

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Subnetting steps:
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host=
subnets=

1.binary–>Bits
2.bits–>mask–>increment
3.increment–>ranges

 

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EIGRP – OSPFv2 – RIPv2
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RIPv2:
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Distance Vector
updates every 30 seconds full route table.
VLSM = yes
AD = 120
MD5/txt authentication
Equal Cost LB = yes
Split-horizon = yes
multicast address – 224.0.0.9
hop count = metric
default LB paths = 4
Hold down time = 180 seconds
Default has auto-summarization.
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EIGRP – hybrid – cisco
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metric is cost = 256x(band+delay)
hybrid = DV + LS
loads route table full 1st time neighbors are established.later only
VLSM support yes
updates are multicasted with:
224.0.0.10 multicast address.
split-horizon yes
AD = 90
hello packets send????
DUAL algorithm or SPF shortest path first.
neighbor adjacencies
Unequal cost load balancing = yes
Variance command used.
Use variance command any metric cost lower than FD in topology table will be put

into routing table if under the value of the FD (feasible Distance)

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OSPFv2
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Link state only
224.0.0.5 multicast
LSA updates
no need for split-horizon too fast to cause loops
VLSM support yes
AD = 110
Deadtime = (4 x hello)
Dijkstra and or SPF algorithm
Metric = bandwidth
neighbor adjacencies
OSPF cost = 10^8/band(bps)
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sProtocol = AD   multicast:

RIP      = 120  .0.9
EIGRP    = 90   .0.10
OSPF     = 110  .0.5

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TCP vs UDP and OSI model vs TCP Model full 360 view

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OSI vs TCP brief

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TCP Explained in Detail

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What does UDP have in common?   5 fields;

source port, destination port, length, checksum, data variable

 

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TCP model vs OSI model

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