Skip to main content

ARP-Address resolution protocol


The address resolution protocol (arp) is a protocol used by the Internet Protocol (IP), to map IP networkaddresses to the hardware addresses used by a data link protocol. The protocol operates below the network layer as a part of the interface between the OSI network and OSI link layer.

ARP Cache:           
Since sending an ARP request/reply for each IP datagram is inefficient, hosts maintain a cache (ARP Cache) of current entries. The entries expire after 20 minutes.

 ARP Packet format

Labels:

Comments

Post a Comment

Popular posts from this blog

What is QinQ(IEEE 802.1ad)

What is QinQ In this section, we will see about Switching concept QinQ. In service provider networks, This is very important. Service provider use this Switching function to pass customer data from one end to other end with two vlan id’s in own switching network.  Explanation: The QinQ technology is called VLAN dot1q tunnel, 802.1Q tunnel, VLAN Stacking technology. The standard comes from IEEE 802.1ad and it is the expansion of the 802.1Q protocol. QinQ adds one layer of 802.1Q tag (VLAN tag) based on the original 802.1Q packet head. With the double layers of tags, the VLAN quantity is increased to 802.1Q. QinQ encapsulates the private network VLAN tag of the user in the public(service provider) network VLAN Tag to make the packet with double layers of VLAN Tags cross the backbone network (public network) of the operator. In the public network, the packet is passed according to the out layer of VLAN tag (that is the public network VLAN Tag) and the private netw...
Post a Comment
Read more

Beacon Frames, Probe request and response

Beacon frame  is one of the management frames in  IEEE 802.11  based WLANs. It contains all the information about the network. Beacon frames are transmitted periodically, they serve to announce the presence of a wireless LAN and to synchronise the members of the service set. Beacon frames are transmitted by the  access point  (AP) in an infrastructure  basic service set  (BSS). In IBSS network beacon generation is distributed among the stations. Beacons are sent periodically at a time called Target Beacon Transmission Time(TBTT) 1 TU = 1024 microseconds Beacon interval =100 TU (100x 1024 microseconds or 102.4 milliseconds) 1. Timestamp (8 byte) 2. Beacon Interval (2 byte) 3. Capability info (2 byte) 4. SSID (variable size) 5. Supported Rates (variable size) Probe Request:  A station or client becomes active or on a PC when the wlan card it enabled it becomes acti...
Post a Comment
Read more

Difference between Polling and Trap in Network Management – Which one is better?

A Network Manager’s job is to get data from Network Elements and present it to the administrators or operators. There are two ways of doing this activity:  1) Polling and 2) Trap . Here is a quick difference between the two: Polling  : A traditional way of providing operators with the network elements information. It’s characteristics are as follows: ·        Pull Mechanism – Requests and get information from network elements at periodic intervals. The periodic interval is most often configurable. ·        Provides non-real time information. It may happen that some changes happen in network element but polling happens an hour after that. Thus, operator gets to know about the changes after an hour. ·        Higher bandwidth needed. Traps  : When an alarm situation exists a trap can be generated, or if some changes happen at network element, an attribute value chang...
Post a Comment
Read more