Monthly Archives: April 2013

3.1.b Identify implement and troubleshoot IPv6 addressing and subnetting

doyle…

MAC Address:
0000:0B0A:2D51
MAC Address 00:00:0B:0A:2D:51 in Binary:
00000000 00000000 00001011 00001010 00101101 01010001
U/L Bit
0xFFFE Inserted in Middle:
00000000 00000000 00001011 11111111 11111110 00001010 00101101 01010001
0xFFFE
U/L Bit Flipped:
00000010 00000000 00001011 11111111 11111110 00001010 00101101 01010001
U/L Bit
Resulting EUI64 Interface ID:
0200:0BFF:FE0A:2D51

this is a great example… pairs of 4 result in the hex values…

0000 0000 becomes 0000 0010 after u/l bit is flipped (7th bit) 0 and 2 for 02

next pair 0000 0000 nice and easy, we now have 02 and 00 for 0200

next pair 0000 01011 = 0 and (8+2+1=11) decimal or B hex… we  have reached 48 bits to have:

0200:0B

insert FFFE

0200:0BFF:FE

append MAC 0A:2D:51

0200:0BFF:FE:0A:2D:51

a 64 bit link local prefix is prepended to complete the operation… ie:

FE80::0200:0BFF:FE:0A:2D:51

catenet… rfc 791 IP…

                           INTERNET PROTOCOL

                         DARPA INTERNET PROGRAM
                         PROTOCOL SPECIFICATION

                            1.  INTRODUCTION

1.1.  Motivation

  The Internet Protocol is designed for use in interconnected systems of
  packet-switched computer communication networks.  Such a system has
  been called a "catenet" [1].  The internet protocol provides for
  transmitting blocks of data called datagrams from sources to
  destinations, where sources and destinations are hosts identified by
  fixed length addresses.  The internet protocol also provides for
  fragmentation and reassembly of long datagrams, if necessary, for
  transmission through "small packet" networks.

"Catenet is an obsolete term for a system of packet-switched communication 
networks interconnected via gateways."

1.1.d Explain IP operations

doyle, from routing tcpip vol 1

the router will send three packets with the TTL set to one; the first router will decrement it to zero, drop the packets, and send back error messages to the source. By reading the source address of the error messages, the first router on the path is now known. The next three packets will be
sent with a TTL of two. The first router decrements to one, the second to zero, and an error
message is received from the second router. The third set has a TTL of three, and so forth,
until the destination is found. All routers along the network path will have identified
themselves.

 

filtering multiple arguments…

i wrote about this one before, but yesterday i forgot it, and then remembered it thanks to stretch over at packetlife… it’s worth noting… if you want to filter  multiple outputs from the cli, simply use multiple “|”‘s without spaces after the intitial filter as below:

R1#sh ver | i 36|Config
Cisco IOS Software, 3600 Software (C3640-JK9S-M), Version 12.4(8), RELEASE SOFTWARE (fc1)
ROM: 3600 Software (C3640-JK9S-M), Version 12.4(8), RELEASE SOFTWARE (fc1)
Cisco 3640 (R4700) processor (revision 0xFF) with 124928K/6144K bytes of memory.
Configuration register is 0x2102

R1#sh run | i ver|host|aaa
version 12.4
hostname R1
no aaa new-model
no ip http server
no ip http secure-server
ntp server 120.100.123.3
R1#

note space for first argument… note no spaces thereafter…

be careful what you filter on, you just might get it…