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| larkspur 2003-02-09, 7:02 pm |
| Is this right I keep getting confilcting info. tia
ARP - Known IP to unknowm mac
RARP- known mac to unknown IP
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| ANDRONDA 2003-02-10, 9:00 am |
| Yes and as I recall tehre was a question on this for CCNA. | |
| larkspur 2003-02-10, 9:39 pm |
| so yes I am right or darthfeces is correct. I am still finding conflicting info. even on practice questions. todd's book, techskills, and the ccna cd-rom. I read the link. Who knows ? | |
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| I think your correct.
Think about when you try to ping a PC - you put in the IP address and an "arp" request is sent to resolve it to a mac address.
Quote from the link-
When the network layer has determined the destination station's network address, it must forward the information over a physical network using a MAC address. Different protocol suites use different methods to perform this mapping, but the most popular is Address Resolution Protocol (ARP).
Here's a couple more links for you:
http://makeashorterlink.com/?I25D35B63
http://makeashorterlink.com/?L16D22B63
http://makeashorterlink.com/?X37D11B63 | |
| larkspur 2003-02-11, 6:16 am |
| that is how I understood it. Thanks for verifiying. I did a arp /? from the cmd prompt and that is how I got my answer as well. Thanks again. By the way is techskilld good for practice ?'s ? | |
| Galactus 2003-02-11, 6:56 am |
| quote:
Originally posted by darthfeces
no
arp takes a known mac and finds an ip
rarp does the opposite
Eh???
This has totally confused me now!
I have in front of me a Cisco books that states:
"ARP is the method IP uses to discover the destination MAC address....it is used to resolve or map a known destination IP address to a MAC sublayer address to allow communication on Ethernet medium"
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| darthfeces 2003-02-11, 8:41 am |
| lets see
rarp = diskless workstation
mac is known and ip needs to be resolved
arp
as mc said ip is known and needs to find a mac address to match to a mac on a local interface or next hop gateway mac address.
thanks mc | |
| wirelessboy 2003-02-11, 9:19 am |
| I am really surprised at the confusion going on.
ARP is used to fine the destination MAC address of a host.
Remember, an IP address helps us to take the packet upto the last subnet, till the end router, now the router knows the IP but does not know the MAC, unless we know the MAC how can we encapsulate the original packet and send it to the particular individual host.
So ARP sends a all F's Broadcast
Your IP is x.x.x.x what is ur MAC?
The correct host, responds with
My IP is x.x.x.x and My MAC is yyyy.yyyy.yyyy
Now the router knows the MAC of host and also the IP, so all the packets to that particular host can now be encapsulated fully and sent to it.
Inverse ARP or RARP is just the opposite - Known MAC to Unknown IP, like in Frame-Relay or BOOTP
Proxy ARP is what intermediate Routers use to get the MAC of destination host, so the FROM MAC add will be the routers MAC and not the MAC of the sending host.
regards | |
| larkspur 2003-02-11, 9:17 pm |
| Try arp /? from your cmd prompt and see what you get . This is what I got.
C:\>arp /?
Displays and modifies the IP-to-Physical address translation tables used by
address resolution protocol (ARP). | |
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