Analyzing Distributed Network Conditions: Understanding Protocols And Their Performance Essay.

This assignment is designed to develop deeper analytical understanding of different distributed network conditions.
At the completion of this assessment students should be able to:
a)Use various technologies and techniques for networked application m anagement, deployment and performancetuning.
b)Describe important networked application architectures and technologies.
c)Analyse performance and deployment related issues for networked applications Employ industry relevant tools and techniques for managing networked applications.

Analyzing the protocol in terms of QoS and overall network performance

Protocols that are sometimes referred to as the access method for communications, hence we define protocols as the standards that are used for defining the exchange of data over the network such as Local Area Network (LAN), Internet etc. Each and every protocol has the set defined purpose and methods along with the specified format that governs the exchange of the data between the two communicating parties. Few of the most used protocol are TCP, HTTP, SMTP etc. these protocols help in communicating data over the World Wide Web or internet.

The communication protocols provide the system for the communicating parties to exchange information in form of data packets with any kind of physical quantity. These rules include the syntax, synchronization, semantics and error recovery functions to communicate in every possible situation. The protocols might be implemented over the hardware or even on software and most it is the combination of both.

Communicating parties uses the defined formats in order to exchange the messages from each other, each of the message that is being exchanged has a meaning and defined response to the particular message for that pre-defined situations. The entire specified behaviour is totally independent on how it has been implemented.  All the communicating parties have to agree upon the communication protocol.

It is an open source protocol that is used to access the information stored over the network centrally. As it is based over the X.500 protocol which is used for directory sharing but LDAP is quite simple and less complex than X.500 protocol, in terms of resources as well LDAP uses lesser amount of resources than X.500, hence it is sometimes being referred to as “X.500 Lite version”.

As in X.500 the LDAP organizes all the files and information in directory based hierarchical model. These stored directories can be used as Network Information Service with storage possibilities that are greater than ever. Using this feature, one can access their account over the network using any machine that has the LDAP enabled. [1][2]

In many situations, the LDAP can be used as an virtual phone directory, this allows user to access the contact information of other clients over the network. But LDAP being more flexible in the sense of phone directory as it is able to query all the servers that have enabled LDAP hence, it provides the ad-hoc repository of all the users around the world globally. Though, LDAP is more being used in private organizations, government organizations and universities around the globe.

LDAP is a standard directory service for all users using the internet for global queries and intranet for inter organization based queries for retrieval of information from multivendor based directories. Hence, the networking protocol is used for querying and modify various directory based services that are running over the TCP/IP. The latest version of LDAP is LDAP version 3 which enables apart from user the hubs, routers, switch etc. the interface that can be used to write the information to the directories. The various vendors of Equipment use this protocol to write and update their directory information. The current version of the LDAPv3 ETF RFC 3377 is defined.

LDAP QoS

The LDAP’s network performance varies in different operations that are being performed over the directories. The LDAP is performance in lower loads on the sever is quite acceptable but with higher loads on the server have led to performance being taken a dip. The performance of the LDAP over the queries that are related to update or add have shown lots of time and resources being consumed even at the lower CPU loads, this is due to the fact of the write and lock operations performed by the LDAP and the resources being updated to revert the entire new updated directory. This is not so much with the case where the server is queried for search based query execution, because it doesn’t require any lock over the data and simple query to search for the records is being performed from the central storage.

This protocol works over the distributed file system protocol that was developed by Sun Microsystems in the year 1984, this protocol allows the users to access the network resource of storage just like it would be using the local storage on their own system.  It is built over the Open Network Computing Remote Procedure Call (ONC RPC) system. The NFS being the open standard that defined in the RFC (Request for Comments) which enables anyone developing applications based on network directory services can use the NFS and modify if needed for its own suitable needs. The PEP (policy Enforcement Point) is the main point which enables the network device or policy on the network device to enforce the said rules over the network. [5] It might reside on any node that is a server or client or any of the working node between the path of client and server. The LPM (Local Policy Module) is the module that helps in enforcing the policy on the network devices and control devices that are policy aware. The RSVP modules requests the LPM in order to obtain the receipt the RSVP messages and take decision based on the instructions provided. The PDP (policy driven point) acts as the logical interpreter that interprets the policies set on the network and forms the RSVP requests and responses to communicate over the network. It is the PDP who decides who gets all the attention in terms of QoS, from which node to end node and using which path. The PDP as discussed takes decision based on the administrative policies that usually reside on the remote database directories like directory service and network file systems. [5][6]

The PEP and PDP are usually resided on the same machine but can be deployed on to others as well. The issues related to scalability and consistency are their if you enable the PEP and PDP on the same machine. Therefore, the distinct policy server must be there to cater multiple PEPs based machines. The PDP’s are generally useful in the cases where network monitoring is needed, with all the data passing through the central controlling hub, the central headquarters manage the services and serve the QoS requesting network traffic to have prior approval from the central controlling node.

This usually means that the file server has no prior information of the client, thus there are no NFS based connections on the system. For example, any NFS to open a file would need to store the information about the file but in NFS they store the file as the file handle, these file handles are unique in nature and are immutable identifier to the respective files. Using the i-node number or disk blocks the uniqueness is being formed in different handlers over the NFS. With the read procedure in place the client must specify the file handle in order to proceed with the read operation, the identical reads on the file would lead the exactly the same results.  The NFS performance related to RPC as the RPC being only the request and reply based protocol only. The NFS performance in is very poor over WAN and very good over the Faster LANs.

The findings suggest that the protocols indeed functions as per the standards that are being defined and have all the said procedures and architecture in place for message communication over the network. All the paths and procedures used as per the standard prescribed in the RFC.

Conclusion

There are two conclusions of the respective LDAP and NFS that can be derived:

1. The LDAP is quite efficient protocol which is being used for directory listing and communicate the directory information over the network to which the LDAP based machine needs no prior information to being communication over it.
2. The NFS protocol that is being analyzed and observed in RPC protocol over the TCP exchange required messages and operations over the network. It was also found using the literature survey that the NFS is quite slow over the WAN and fast on Local Ethernets.

References

[1]J. Cortes, "A brief introduction to LDAP and its future", IEEE Distributed Systems Online, vol. 5, no. 4, pp. 1-3, 2004.

[2]"RFC 7612 - Lightweight Directory Access Protocol (LDAP): Schema for Printer Services", Tools.ietf.org, 2017. [Online]. Available: https://tools.ietf.org/html/rfc7612. [Accessed: 30- Apr- 2017].

[3]V. Koutsonikola and A. Vakali, "LDAP: framework, practices, and trends", IEEE Internet Computing, vol. 8, no. 5, pp. 66-72, 2004.

[4]A. An, Foundations of intelligent systems, 1st ed. Berlin: Springer, 2008.

[5]S. Guo, W. Yang and G. Wang, "NFS Protocol Performance Analysis and Improvement for Mobile Transparent Computing", 2013 IEEE 10th International Conference on High Performance Computing and Communications & 2013 IEEE International Conference on Embedded and Ubiquitous Computing, 2013.

[6]B. Li, P. Zhang, Z. Huo and D. Meng, "Early Experiences with Write-Write Design of NFS over RDMA", 2009 IEEE International Conference on Networking, Architecture, and Storage, 2009.

[7]Weikuan Yu and J. Vetter, "Initial characterization of parallel NFS implementations", 2010 IEEE International Symposium on Parallel & Distributed Processing, Workshops and Phd Forum (IPDPSW), 2010.