End to End Internet Packet Dynamics

This paper is a report based off of measurements off of the internet between 1994 and 1995. It tries to evaluate the performance of the internet and observe if there are any anomalies or weird dynamic behavior within the internet and specifically TCP. The paper evaluates several things, including out-of-0rder delivery, packet corruption, bottleneck bandwidth, packet duplication, packet delay etc. It takes traces from real internet data and analyzes the effects of each one.

A couple interesting things i saw from the paper. I didn't even know that packet duplication existed within the internet. Thus, when i read about it in the paper, it was quite interesting. Them receiving 9 copies of the same packet, that was kind of funny. The paper also studied the out of order delivery behavior of packets in the internet, and observed that it wasn't a rare event. But our of order doesn't necessarily decrease performance.

Overall i think these kind of studies can help us conclude a lot about specific internet behavior, such as TCP, in a specific region, but the whole internet is so complex and large, that it's hard to factor in everything when taking these huge amounts of data. Especially since they don't know about other traffic information, so the packet loss and packet delay etc can be caused by different factors. The next paper introduces another way of gathering data and analyzing the network, which takes on a more active role than purely analyzing packets.

Middleboxes no longer considered harmful

I had a hard time following this paper, since the main motivation for it i didn't truely understand. From what i've read, it seems like instead of trying to prevent NAT boxes or other middle boxes from existing within the network, they tried to setup a framework that allowed the NAT boxes to co-exist. One of the main methods of doing that was to basically give every unique internet host a unique identifier. However, besides the fact that it breaks the network layer infrastructure, i don't really see how firewalls and NAT boxes are harmful, infact, since i use a router i home, it seems to me that they are more beneficial then harmful, just because they can protect a user from being directly connected to the network, and can filter out harmful traffic. As a result, i didn't really understand the point behind this paper.

Internet Indirection Infrastructure

This paper is quite interesting, introducing an overlay on top of the current network architecture to create an abstraction that allows for more efficient implementation of different services, including multicast, or mobile networks. This overlay network utilizes a rendezvous based communication method which isolates senders and receivers so that the packet a sender is sending can be received by different receivers, or processed and routed differently depending on the receiver's request. This is done by unique id's on the sender and receiver side which is matched to ensure the transmission of the data. The underlying implementation of the overlay is using the chord lookup like the previous paper.

I think the idea of this is definitely very interesting, because it allows for abstraction on top of existing network solutions in which can easily implement several different services. However, despite the security section mentioned in the paper, it still seems like using the id for authentication of receiving messages might be really susceptible to eaves dropping. But it is true that the current Internet architecture is no better. One question i had is how the chord lookup table will affect the normal routing of the packets, since it seems like it's more work to have to go through the lookup table just to send a packet. But overall, i liked the paper, and it seemed like a good idea. Since this paper is from 2002, are there are any active deployment of it?

DNS Performance and the Effectiveness of Caching

This paper had a lot of data in it. Most of the paper was about how the data was collected and explaining the data. They collected it over several servers connecting MIT and Korea AI labs. One interesting thing is that the traces they collected didn't include the cached queries, so even though they said that it there were 23% DNS that were unanswered, it doesn't include the cached entries, which might have also accounted for a bulk of the queries.

After the analysis, the paper attempts to observe the effects of caching and adjusting the TTL to the network. Intuitively it seems like the longer the TTL, the better, since there will be less requests and most caught by caching. The paper concluded that the decreasing TTL didn't effect performance, but i thought their data that was collected from before was no including cached requests, so it's weird that they can make this claim. Caching does allow better load balancing as well, because all the requests don't need to consistently go to the same server over the wide area network.

Development of the Domain Name System

This paper is a good introduction paper on the domain name system and it talks about the purpose of the domain name system and what they had in mind when they were developing the domain name system. With the DARPA net, centralized management of anything seemed to be a bad idea, since the purpose was fault tolerance. Thus, DNS was designed so there was no central management, but instead a distributed system of matching names to hosts. It worked by establishing records, and whenever a host needs to do a lookup, it can look it up locally first, and then the requests can move up to the different root servers. The namespace is also split into different zones, to spread out the distribution even more.

In the paper it mentioned the current implementation status, and how applications had to be recompiled to convert from the old HOSTS.TXT to DNS. It seems now DNS is the standard and maybe the only way to do domain name lookup, i wonder if all the applications converted successfully, or does HOSTS.TXT still exist and is being used only by a small portion of the users on the internet.

Chord: A scalable Peer to Peer lookup service for Internet Applications

This paper goes into more depth specifically about the Chord routing method, which is a skiplist-like routing, according to the previous article. The paper lists the goal of Chord, which is to address load balancing, decentralization of control, scalability, availability and also flexible naming. The Consistent hashing is what takes care of the distributed and load balancing, since it can provide any joining node a distributed way of locating evey key in the network. Chord offers a simple way of searching for data in distributed P2P system. It also provides mechanism to continue its correctness of functionality despite partial correctness of a node's information.

I don't know much about P2P applications or the underlying functions of them, but from the previous paper and this one it seems there are a lot of challenges that need to be solved. And the distributed property of P2P applications seem like a very propelling motivation, to be able to spread data quickly from a distributed source. Chord is looking at the searching function of P2p applications, but other issues i image also can be looked into, including how to efficiently download data, and algorithms to distribute that.

Looking up Data in P2P Systems

This article gives a brief introduction to some of the difficulties of P2P computing. It does first list the attractive reasons for P2P systems, including fault tolerant because of its decentralized nature. The challenge of course is how to efficiently use the distributed system. The article specifically talks about the look up problem of trying to find data in this huge distributed system. A broad range of techniques are evaluated and compared to each other, and briefly explained. All of them are based on a distributed hash table. These include the Chord skiplist like routing, tree-like routing, and a multi-dimension routing.

It's hard to determine which routing method is the best, as the summary of the article lists several open questions about the fault tolerance, routing, and security behaviors for malicious nodes. In the article, it does acknowledge the fact that most people directly associate p2p applications with illegal file sharing, including napster or KaZaa. The paper mentions that there are other applications, but i'm not sure if i can think of any off the top of my head...