OSI CRITICAL

I am currently studying for the exam and theres just to much contradiction out there. Anywayz could someone plz clear up for me what layers of the OSI does the NIC, MAU, CSU/DSU, WAPs operate. Especially for certification purposes how does Comptia and Cisco view this?

Thanks techs

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ally_uk

NICS are assigned MAC Addresses and operate at the data link layer

CSU/DSU - Physical layer it terminates physical data connections

MAU - Physical Layer

I'm not sure which layer a wireless access point operates at my guess would be Physical

Hope this helps

configure terminal

ally_uk wrote:

NICS are assigned MAC Addresses and operate at the data link layer

CSU/DSU - Physical layer it terminates physical data connections

MAU - Physical Layer

I'm not sure which layer a wireless access point operates at my guess would be Physical

Hope this helps

Thanks for clarification!!!!!!!!

malcybood

configure terminal wrote:

ally_uk wrote:

NICS are assigned MAC Addresses and operate at the data link layer

CSU/DSU - Physical layer it terminates physical data connections

MAU - Physical Layer

I'm not sure which layer a wireless access point operates at my guess would be Physical

Hope this helps

Thanks for clarification!!!!!!!!

If I'm wrong the someone correct me but I understand Access points as operating at both layer 2 and layer 3.

Layer 2 is the layer that encryption operates at but Access points also use IP to communicate which is the network layer part.

It appears to be bit of a grey area but if I was given every layer to pick from in a question EXCEPT layer 2 then I would pick layer 3 as communication is over IP and encryption is optional and vice versa if network layer was not available.

Cisco Aeronet WAP documentation mentions the above in this document

http://www.cisco.com/global/CH/de/solutions/smb/isr/cisco_aeronet.pdf

sprkymrk

From this sites own TechNotes:

http://www.techexams.net/technotes/networkplus/osimodel.shtml

NETWORK (LAYER 3)

The Network layer converts the segments from the Transport layer into packets (or datagrams) and is responsible for path determination, routing , and the delivery of packets across internetworks. The network layer treats these packets independently, without recognizing any relationship between those individual packets. It relies on higher layers for reliable delivery and sequencing.

The Network layer is also responsible for logical addressing (also known as network addressing or Layer 3 addressing) for example IP addressing. Examples of protocols defined at this layer are IP, IPX, ICMP, RIP, OSPF, and BGP. Examples of devices that operate on this layer are layer-3 switches and routers. The latter includes WAPs with built-in routing capabilities (wireless access routers).

DATA LINK (LAYER 2)

The Data Links provides transparent network services to the Network layer so the Network layer can be ignorant about the underlying physical network topology. It is responsible for reassembling bits, taken of the wire by the Physical layer, to frames, and makes sure they are in the correct order and requests retransmission of frames in case an error occurs. It provides error checking by adding a CRC to the frame, and flow control. Examples of devices that operate on this layer are switches, bridges, WAPs, and NICs.

Webmaster

Additionally, check out my Wireless Networking TechNotes, which include a piece about WAPs and explain how it relates to the OSI layers and why:
www.techexams.net/technotes/networkplus/wireless-networking.shtml#WAP

configure terminal

Webmaster wrote:

Additionally, check out my Wireless Networking TechNotes, which include a piece about WAPs and explain how it relates to the OSI layers and why:
www.techexams.net/technotes/networkplus/wireless-networking.shtml#WAP

Thanks guys, bn very helpful.