Protocol Level Tests

In networking Domain we have many types of protocols and we need to test basic functionality of all protocols. When we say " Protocol level tests" we mean the networking protocols which comes in Layer 2-7. Layer 1 is physical layer and to test it we need specilized hardware devices.
In L2-L7 we have many protocols which we can tests. Some of the protocols which is required by router, modem, switches and bridges are given below . I will be adding how to test them and the general guidelines to test these protocols. When I am referring to layers they are layers of OSI model.  For who does not know or new to protocols or embedded system tests , the OSI layer is basically a model which has divided all the fuctions of communication systems into layers. This was done for interoperibility and understanding purposes. We have TCP/IP model as well which talks in terms of 4 layers which are mapped to OSI layers for understanding purposes.
We have protocols which resides in respective layers are given and categorised below. The important one are mentioned below :
Layer 1 - Physical layer-Actual Physical meduim , RS-232, RJ45, T1, E1, 10BASE-T, 100BASE-TX, POTS,DSL, 802.11a/b/g/n PHY ( This is where hub works, basically hub doesn't have any intelligence it just forwards data received on one port to all other ports )
Layer 2- Data Link Layer- MAC and LLC Layer ,  802.3 (Ethernet), 802.11a/b/g/n MAC/LLC, 802.1Q (VLAN), ATM,FDDI, Fibre Channel,HDLC, ISL, PPP, CRC, STP, RSTP  ( This is the Layer in which Bridge and Switches works, they read the MAC address of the data received and map it  with the port on which it is received.)
ARP in between Layer 2 and 3 , it help in getting MAC address for corresponding Ip address.
Layer 3 - Network Layer - IP, IPsec, ICMP, IGMP, OSPF
Layer 4 - Transport Layer - TCP, UDP
Layer 5 - Session Layer -NetBios, L2TP, PPTP
Layer 6 - Presentation Layer - MIME, SSL