Back to Basics - Open System Interconnect - FC Layers - Infrastructure Services BIND

Upper layers - Application, Presentation and Session - Performs all task of upper layer in the application or browser itself.

Application Layer - Top layer of the OSI has many protocols like http, ftp, telnet, smtp that are used by the application to communicate to lower layers of OSI.

Presentation Layer - Data received from the application layer is in ASCII format, that needs to be translated into EBCDIC.

·         ASCII -> EBCDIC

·         Compression

·         Encryption (SSL)

Session Layer - Connection establishment is done using APIs (NetBIOS). Performs Authentication, Authorization.  Session management by keeping track of order and type data received. It terminates connections when not required.

Low Layer - Transport, Network, Data, Physical

Transport Layer - It performs Segmentation, Flow control (Sender and Receiving devices communicate with each for agreed speed of data flow) and Error Control(checksum) of data. TCP is connection oriented for reliable communication and required to acknowledge.  UDP is connectionless and does not required to send acknowledgement because of this reason it is faster than reliable TCP protocol. Each segment of data has port number and order id to identify originating application and proper ordering of data segments.

Network Layer - Segments received from Transport layer are placed(encapsulated) in the packet with source and destination IP address.  Performs the routing.  It Also checks for suitable paths using RIP(Interior gateway protocol used in INTRADomain routing i.e. routing within single autonomous system, based on distance vector which chooses route with minimum number of hop count. Max hop count supported are 15. protocol UDP port 20) OSPF(Interior Gateway Protocol used in INTRADomain routing i.e. routing between single autonomous system(network controlled by single entity) based on the shortest path, IP protocol port 89, link state), BGP(Exterior Gateway Protocol used in INTERDomain routing i.e. routing between multiple autonomous systems based on best path selection TCP protocol port 179 path vector)

Data Layer - Packets received are appended with MAC address (12 hexadecimal character) of source and destinations.  Frames reached to device using destination MAC address. At destination, MAC address is removed and IP address in the packet used to reach to correct IP address.

Physical Layer - Transfers frames in binary and convert them to electric signal(copper), light(fiber) or waves(wireless) depending on the media used.

Receiving side performs all given operations in reverse and eventually application on local system communicates to application on remote system.

OSI model is theoretical in practical we TCP/IP Layer model is used. Good things is that it is similar to OSI model.  Upper three layer of OSI Application, Presentation and Session are merged to form single Application Layer. In TCP/IP layer model there are five layer Application, Transport(segments), Network(packets), Data(frames), and Physical.

Like OSI model Fibre Channel has similar layer structure.  It has 5 layers(starting from 0) in cotrast with the 7 layers of OSI.

FC-4: Defines application interfaces that can execute over Fibre Channel. It performs mapping of protocol like (SCSI-FCP), means it allows SCSI commands to use FC infrastructure using FCP.  Similarly we can have IP (FC-IP), FICON (FC-SB-2), FC-TAPE (FCP-2).  There is newer one FC-NVMe which allows NVMe to use FC and is generally call NVMe over FC (Maps SCSI to Fibre Channel using FCP)

FC-3: performs advanced features like striping(transfering 1 data units to multiple links), hunt group(mapping multiple ports to single node) 

FC-2: It divides data into frames. It perform flow control and checks how much data needs to be sent and classes of service (Frames payload 2112 byte,  Sequence is formed by a set of one or more related frames transmitted unidirectional from 1 N-Port to other,  Exchange is nonconcurrent sequence for a single operation)

FC-1: Performs encoding/decoding 8b/10b (1,2,4,8) 64b/66b(10,16,32)

FC-0: Defines physical link in the system cables, sfp

Socket type LGA (Land Grid Array), PGA (Pin Grid Array), BGA (Ball Grid Array) - The way a CPU interfaces with the socket on a motherboard.  LGA is used on Intel sockets with pins as part of the socket.  AMD's AM4 solution, PGA, has the pins are on the processor, and these fit into holes on the socket.  AMD's Threadripper CPU also use LGA sockets. A BGA socket is one in which the processor is permanently soldered to the motherboard, typically on a laptop.

MBR - EFI

MBR has a partition table that indicates where the partitions are located on the disk drive, and with this particular partition style, only volumes up to 2TB (2,048GB) are supported. An MBR drive can have up to four primary partitions or can have three primary partitions and one extended partition that can be divided into unlimited logical drives.

Windows Server 2012 R2 can only boot off an MBR disk unless it is based on the Extensible Firmware Interface (EFI); then it can boot from GPT. An Itanium server is an example of an EFI-based system. GPT is not constrained by the same limitations as MBR. In fact, a GPT disk drive can support volumes of up to 18EB (18,874,368 million terabytes) and 128 partitions. As a result, GPT is recommended for disks larger than 2TB or disks used on Itanium-based computers.

 

Basic - Dynamic

Windows Server 2012 R2 supports two types of disk configurations: basic and dynamic. Basic disks are divided into partitions and can be used with previous versions of Windows. Dynamic disks are divided into volumes and can be used with Windows 2000 Server and newer releases. When a disk is initialized, it is automatically created as a basic disk, but when a new fault-tolerant (RAID) volume set is created, the disks in the set are converted to dynamic disks. Fault-tolerance features and the ability to modify disks without having to reboot the server are what distinguish dynamic disks from basic disks.  A basic disk can simply be converted to a dynamic disk without loss of data. When a basic disk is converted, the partitions are automatically changed to the appropriate volumes. However, converting a dynamic disk back to a basic disk is not as simple. First, all the data on the dynamic disk must be backed up or moved. Then, all the volumes on the dynamic disk have to be deleted. The dynamic disk can then be converted to a basic disk. Partitions and logical drives can be created, and the data can be restored.

WDS - Windows Deployment Service

WSUS - Windows Server Update Service

IANA - Internet Assigned Number Authority (Governing Body maintaining IP Address)

ICANN - Internet Corporation for Assigned Named and numbers (Governing Body maintaining DNS service). This assigns the control of TLD to one or more organization. In turn, organization delegates portion of  DNS namespace to other organization.  for example example.com. Registrar has delegated the control over example.com node in the dns tree while controlling TLD of .com.  Within the portion of example.com dns host and records can be created. example.com can be further divided into ksa.example.com india.example.com called subdomain each domain and subdomain are associated with DNS nameserver. It means every node in the dns can have 1 or more server to give authoritative answer to queries about that domain. At the root of domain namespace are root servers.

Given are 3 excerpts from MCSA Windows 2012R2 Sybex Study Guide showing name resolution and reverse resolution

1. DNS sends recursive query to look for india.example.com to local DNS server and in case it find no zone corresponding
2. Forwards the request to root servers. Root name server has authority for root domain. In turn root server provides the IP address of name server  for .com top level domain.
3.  Local server send the request  of www.india.example.com to received IP
4. name server for www.example.com send IP address of nameserver authoritative for www.example.com
5. Local DNS server send the resolutions request to server authoritative for www.india.example.com which  In turns provide IP address of server authoritative for www.india.example.com
6. Local DNS provides the IP to client

DNS zone is a portion of DNS namespace over which specific DNS server has authority. Within zones there are Resource Record that define hosts and other type of information that make up database for the zone.

Bye...