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  • CCNA Boot Camp
    world depends on you people becoming Cisco certified You each will become a CCNA Every time you see a router that does not say Cisco on it you will kill it What are you going to do ladies Kill Kill Kill That s right Each week we will be adding a new lesson so that you will become strong of mind and pure of heart We are going to rid

    Original URL path: http://www.routergod.com/ccnabootcamp/index.html (2016-04-27)
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  • The Wonderful OSI Model
    function if I flash them using Morse code to actually communicate using words that s a Datalink function The Datalink layer is in contact with the Datalink layer of the remote machine it is communicating with The Network Layer Layer 3 is the network layer This is where IP works IP addressing is a man made hierarchical addressing scheme that must be converted to a MAC address when a packet is sent on the final hop to where ever it is going The units of data that the network layer use are called packets Now that we re up here in layer 3 we should talk about encapsulation Encapsulation is the process of data from a higher layer and adding a new header or control data to it and passing it to a lower layer For example layer 4 is the transport layer it s data are called segments these segments are handed down to the network layer where it gets an IP header assuming we re using TCPIP added to the front of the segment mow it is called a packet and it is handed down to the Data link layer where it is wrapped in an Ethernet Frame assuming we re using Ethernet and applied to the network cabling where it is seen as bits So the OSI model when data is passed down it becomes the payload of each lower layer as each layer adds it s own information This process is reversed when data is received The network layer is in contact with the network layer of the remote machine it is communicating with Because IP or any layer 3 addressing scheme is a logical man made system for assigning individual addresses to computers it has a terrible flaw Computers have NIC cards that use a 48 bit MAC address All data must be sent using this layer 2 MAC address All routing is done at layer 3 The routers hopefully know the route to the subnet that a packet is addressed to but when the packet reaches the final router and is in the output buffer for the interface that is connected to the subnet it is destined for it is stuck it can travel no farther using its IP or layer 3 address Since all data is actually sent using hardware addresses the router must somehow figure out what MAC address is using the IP address in the packet This is done using ARP or Address Resolution Protocol The router sends out a broadcast on the subnet saying which one of you guys is using IP address such and such Since it is a broadcast all hosts on the subnet hear the router ask this question every host checks its IP configuration to see if it is the host the router s asking about The host that has to IP address in question responds to the router with it s MAC address The router now knows which MAC address goes with this IP address

    Original URL path: http://www.routergod.com/ccnabootcamp/osi.html (2016-04-27)
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  • Paul Hogan on HSRP
    HSRP to our audience Paul OK clears throat let s talk about the Hot Standby Router Protocol HSPR is a way for two Cisco routers to share a common virtual IP address while one router is actively routing packets the other router or routers are standing by in case the active router fails It s a very good way to provide fault tolerance In fact if ya take a mind to you can read RFC 2281 to learn a bit more about it Doug So the routers share an IP address How do the routers know when one has failed Paul Let s get back to the IP address besides sharing an IP address that IP address has a common MAC address that the routers share It s like this mate you have a workgroup of say I don t know 100 computers Each one of these machines has been configured with a default gateway if these machines have used the default gateway or router they have it s MAC address in their ARP cache So since the routers in the HSRP group share an IP address with a corresponding MAC address when they fail over the workstations are unaware of the change What they see is a virtual router Doug How do the routers control all this Paul Well mate the routers in an HSRP group send and receive keep alives using the multicast address of 224 0 0 2 and UDP port 1985 By default the hello interval is 3 seconds Once 3 hello intervals pass without hearing from the active router the standby router automatically becomes the active router Each router is configured with a priority number the router with the highest priority number in a standby group is the active router everyone else just relaxes Doug This must be very hard to configure Paul No way mate you only need 2 commands to do it and 2 additional commands to customize it What s more it s configured at the interface that you want to participate in the standby group It s so easy an American could do it Doug No way Really What are the commands Paul Well first off on the router that you want to be the active router go to the interface you want HSRP to run on think up a group number all routers participating in this scheme must use the same group number also think up what IP address you want the HSRP group to share Now watch me type dingo config if standby 1 ip address 10 1 1 254 dingo config if standby 1 priority 100 So what we have here mate is a standby group number of 1 an IP address of 10 1 1 254 that the routers are going to share now let s configure the standby router fosters config if standby 1 ip address 10 1 1 254 fosters config if standby 1 priority 90 OK the only thing different on the standby router

    Original URL path: http://www.routergod.com/paulhogan/index.html (2016-04-27)
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  • Elizabeth Hurley on the Cisco 2600
    him about the Cisco 2600 series of routers Let s join Erwin as he talks to Elizabeth Hurly about Cisco routers Believe it or not Liz doesn t own a single pair of pants Erwin Hey Liz How about telling us about the Cisco 2600 series routers Liz Well let s see where to start Very well the 2600 series is a product aimed at branch offices They come with RISC processors and have 2 WAN card slots and 1 Network card slot Erwin Not too shabby 2 WIC slots Liz Oh I forgot the 2600 WIC modules can also be used in the 1600 1700 and 3600 routers this way you can stock fewer WICs if you have these routers in your enterprise Erwin How much memory do 2600s come with Liz 8 Megabytes of Flash and 32 Megabytes of RAM Erwin The model numbers are kinda confusing how do you know what the numbers mean Liz First off they all start with the number 26 so we can set that aside If the last 2 digits are in the 50s that means a high performance CPU If the last number is a 1 that means it has 2 Ethernet Ports The 2610 is the basic model with one Ethernet port the 2611 has 2 Ethernet Ports Erwin Can you show us a product matrix Liz Sure here goes A poor swimmer Liz often washes up on shore wearing only panties Model CPU Ports 2651 80 MHz 2 FE 2650 80 MHz 1 FE 2621 50 MHz 2 FE 2620 50 MHz 1 FE 2613 40 MHz 1 TR 2612 40 MHz 1 TR 1 E 2611 40 MHz 2 E 2610 40 MHz 1 E Erwin Wow You really seem to know your stuff have you ever thought

    Original URL path: http://www.routergod.com/elizabethhurley/index.html (2016-04-27)
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  • Hank The Angry Drunken Dwarf on DHCP
    DHCP server is configured with a pool of addresses known as SCOPES The DHCP server will automatically assign reusable IP addresses to clients from the SCOPE of addresses The DHCP server can also provide other information along with an IP address like the address of the DNS server default gateway WINS server domain name and what type of NETBios node the client should be Netbios node type What the hell is that Oh now I remember that tells a Microsoft workstation how it should try to resolve netbios names After I get another beer I ll tell you how all this happens then I Hank the Angry Drunken Dwarf will actually configure DHCP on a Cisco router Whoop Whoop I can t even spell DHCP and I m going to configure it Big time Oh yeah Christ I almost forgot your DCHP server actually it s a router running DHCP server emulation on it can be anywhere Your DHCP server does not have to be on the same network as the clients requesting DHCP addresses The clients use broadcasts to find a DHCP server Ha Ha I know what you are thinking routers don t forward broadcasts boy Hank is a dumb ass Well I say up yours Routers do forward broadcasts if you type in the ip helper address command so there I m gonna go chug a couple of beers and I ll come back and we ll figure this all out packet by packet OK I m back let s Hank lets out an impressive belch bbbbbrrrrrrrriiiiiiipppppp excuse me Let s get down and dirty and see how this DHCP works First off some joker in accounting turns on his PC His PC has an IP protocol stack that has already been configured to receive an IP address and related information dynamically So this guy s PC will send out a DHCPDISCOVER packet and this is a broadcast The Cisco DHCP server receives this broadcast and will respond with a DHCPOFFER which is sent via unicast directly to the requesting station pretty cool huh If there are many DHCP servers the workstation may get several replies but usually responds to the first DHCPOFFER it receives If the workstation wants the address offered it will now respond with a DHCPREQUEST again by broadcast this way any other DHCP servers will hear what s going on and privately withdraw their offers If the workstation did not want the address offered it would respond with a DHCPDECLINE message If the workstation replied with the DHCPREQUEST it would receive a DHCPACK from the server indicating that this address and associated information is now theirs to use Workstation DHCPDISCOVER DHCP Server Workstation DHCPOFFER DHCP Server Workstation DHCPREQUEST DHCP Server Workstation DHCPACK DHCP Server Hey you guys this is interesting before a Cisco DHCP server responds with a DHCPOFFER it will ping the address it s offering twice just to make sure nobody is using it That s something you can configure too

    Original URL path: http://www.routergod.com/hanktheangrydrunkendwarf/index.html (2016-04-27)
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  • Arnold Schwarzenegger on PIX Turbo ACLs
    and asked if he would tell us what he knew about Turbo ACLs it turns out he doesn t know much at all but we got a cool t shirt so it was worth the effort Interviewing Mr Schwarzenegger is RouterGod New York Field reporter Gregg Sietsema let s join Gregg as he gets the low down on Turbo ACLs The Next Governor Of California Gregg Hey Mr Governor thanks for taking time out of your busy schedule to talk to us about Turbo ACLS Arnold No problem I vill tell you ahh about twerbo access lists and how they vork on da pigs fya wahh Gregg Well don t forget only on PIX OS version 6 2 and above Arnold Wight They take iny azzes list and make it go faster Gregg Well truth be told they only work on access lists that are 19 or more lines in length Arnold Ahv Cose they oh va klock da CPU un make da PIX run fast ta Gregg Close but actually a turbo access list compiles access lists so that they may be processed more efficiently Can you tell us how much flash is required to maintain compiled or Turbo

    Original URL path: http://www.routergod.com/arnold/index.html (2016-04-27)
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  • Cisco Psychic Hotline!
    all and sees all Your router has come under the influence of a malevolent spirit Your router is possessed by Satan Caller Yes Yes That s what I told my boss but he wouldn t believe me Everything has been fine until today I tried to modify the configuration of this 2620 and suddenly the router will not accept my password Madame Rommon Your router is harboring a secret a bad secret Caller How did you know Yes It says Bad Secrets Oh my God I can t believe you knew that My boss said I needed to perform password recovery but when I saw Bad Secrets on the screen I knew that it was more serious than that Please Madame Rommon tell me what to do Madame Rommon Sweet Child we must perform an exorcism Do not be afraid We must type some sacred commands into the router These are very special commands so special that I will need to charge your credit card an additional 750 Do you authorize this charge Caller Oh Yes It s my boss s personal MasterCard he told me to fix the router so I know it s ok Madame Rommon Marvelous for an extra 1000 I can say a prayer for your router do you authorize that charge Caller Yes Yes Please I ll pay anything Just help me Madame Rommon Do not fret plug your console cable into the router and cycle the power switch when the router reboots Satan will want to load the startup config so you must stop Satan from loading the config Do you understand Caller Yes stop Satan from loading the config how do I do that Madame Rommon You must hit the BREAK key within 60 seconds of the router booting up you will know that you have stopped Satan if you see a prompt with no router name to the left of it Caller Yes I see the prompt now what should I do Madame Rommon OK here is the sacred command enter confreg 0x2142 Caller So far so good now what Madame Rommon Now you must must cause the router to reboot itself so enter the following sacred letter i Caller Wow the router rebooted and now it s asking if I want to enter the initial configuration dialog what do I do Madame Rommon Your router has rebooted without loading the the startup config the startup config is where the old password was stored Your router now has a clear running config but your old config remains safe we just told the router not to load it Say No Now enter Privileged Exec mode by entering the command enable Now you are in enable mode and you didn t need a password The next step is to load the existing startup config from NVRAM into your running config enter the command copy start run Madame Rommon gives CCNP Diane Foster an Anti Hacker mantra at Networkers convention Madame Rommon demonstrates palm reading

    Original URL path: http://www.routergod.com/psychic/index.html (2016-04-27)
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  • Robert Downey Jr. on IEEE 802.3
    Well to begin with there is an 8 byte preamble the preamble is not technically part of the frame as it is added to the front of the frame by the NIC just before the frame is put out on the wire The preamble is a series of alternating one and zero bits Actually Manchester encoding is slightly more complicated than this but for our purposes think of the signaling as a simple on and off type of scheme These 64 bits in the preamble are for timing the allow the receiving station to get synchronized with the incoming signal this usually happens within the first 14 bit times The last 2 bits are switched on so the last byte looks like 10101011 This last byte of the preamble is called the Start Of Frame delimiter and signals the start of the actual frame John I see since there is no clocking the preamble allows the receiver to sync up and it signals the start of frame What is next RDJ The next field is the destination MAC address of course it is 6 bytes in length After that comes the source MAC address and it too is 48 bits in length MAC stands for Media Access Control it is the actual layer 2 hardware address of a device Cisco sometimes refers to it as a BIA or Burned In Address Notice that the destination address is first that saves time when you employ cut through switching John Very nice after the preamble comes the destination and source datalink addresses what follows RDJ The next field is the Length field it is 2 bytes in length and indicates the length of the data or payload of the frame The length does not include the preamble MAC addresses the FCS we ll talk about that in a minute or the length field itself An Ethernet frame cannot be any smaller than 64 bytes in length or larger than 1518 bytes in total length not including the preamble which we don t count anyway John So the length field just indicates the payload length that s pretty simple RDJ Well not so fast one very important thing the length field does is communicate the end of the payload By knowing how long the payload is we know exactly when it will end and when the Frame Check Sequence begins that way we don t need any kind of end of data delimiter or some such thing in our frame John Hey You re pretty good Keep going RDJ Of course I m good that s why they pay me the big bucks Now we get into 3 cool little fields called the LLC header LLC means Logical Link Control Each of these is 1 byte in length and these 24 bits are counted in the Length field Robert strikes an introspective pose for benefit of onlookers All Deputies in Robert s employ are also members of the Screen Actors Guild and receive

    Original URL path: http://www.routergod.com/robertdowneyjr/index.html (2016-04-27)
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