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Path Vector

Path vector

Path Vector Protocol is a computer network routing protocol, sometimes known as a policy routing protocol, that is used to span different autonomous systems. Exterior Gateway Protocol (EGP) and Border Gateway Protocol (BGP) are examples. The routing table maintains the autonomous systems that are traversed in order to reach the destination system. Contrast with distance vector protocol and link state protocol.



Policy based routing

Policy-based routing (PBR) is a term used in computer networking. It refers to a technique used to make routing decisions based on policies set by the network administrator. When a router receives a packet, it normally decides where to forward this packet to based on the destination address in the packet, which is then used to look up an entry in a routing table. However, in some cases, there may be a need to forward the packet based on other criteria. For example, a network administrator might want to forward a packet based on the source address, not the destination address. This is also called source routing. Policy based routing may also be based on the size of the packet, the protocol of the payload, or some other characteristic. It can also be based on a combination of characteristics. (Policy Based) Routing can be based on the source and the destination, i.e. when the packet comes from this source and wants to go to that destination then route to this next hop or onto that specific interface. This allows e.g. to route over different links/towards different networks even while the destination is the same but depending on where the packet is originating from. This can be useful when interconnecting several private networks. If you have the possibility to design an architecture without IP-overlaps, then that is highly recommended over using PBR. On Cisco IOS, PBR is implemented using route maps. Category:Routing Category:Computer networks

Autonomous system (Internet)

In the Internet, an autonomous system (AS) is a collection of IP networks and routers, under the control of one or more entities, that presents a common routing policy to the Internet. See RFC 1930 for additional detail on this updated definition. Originally, the definition required control by a single entity, typically an Internet service provider or a very large organization with independent connections to multiple networks, that adhere to a single and clearly defined routing policy. See RFC 1771, the original definition (now obsolete) of the Border Gateway Protocol. The newer definition of RFC 1930 came into use because multiple organizations can run BGP using private AS numbers to an ISP that connects all those organizations to the Internet. Even though there are multiple autonomous systems supported by the ISP, the Internet only sees the routing policy of the ISP. That ISP must have a public, registered ASN. A unique AS number (or ASN) is allocated to each AS for use in BGP routing. With BGP, AS numbers are important because the ASN uniquely identifies each network on the internet.

Assignment

AS numbers are assigned by the IANA, which also allocate IP addresses, to regional internet registries (RIRs) in blocks. The local RIR then assigns an AS number to an entity from the block assigned by the IANA. Entities wishing to receive an ASN must complete the application process of their local RIR and be approved before being assigned an ASN. Current IANA ASN assignments can be found on their website: [http://www.iana.org/assignments/as-numbers] AS numbers are currently 16-bit integers, which allow for a maximum of 65536 assignments. AS numbers are divided into 2 ranges. The first are public AS numbers, which may be used on the internet and range from 1 to 64511. The second range, from 64512 to 65535, are known as private numbers, and can only be used internally within an organization. While there is no immediate danger of exhausting the 16-bit AS number space, several factors, principally the need of enterprises to run BGP to multihome, is reason for concern that more space will be needed in the moderate term. As of mid-2005, the IETF has several drafts underway that define mechanisms for the use of an upwardly compatible four-octet, or 32-bit, AS number space. This space will not replace the existing 16-bit space.

Types

Autonomous Systems can be grouped into 3 categories, depending on their connections and operation. A multihomed AS is an AS that maintains connections to more than one ISP. This allows the AS to remain connected to the internet in the event of a complete failure of one of their ISPs. In addition, this type of AS would not allow traffic from one ISP to pass through on its way to another ISP. A stub AS refers to an AS that is only connected to a single ISP. This is generally regarded to be a needless use of an AS number, as the network is completely under a single ISP, and thus does not need to be uniquely identified. A transit AS is an AS that provides connections through itself to the networks connected to it. That is, network A can use the transit AS to connect to network B. ISPs are always transit ASs, because it is their business to connect disparate networks in exchange for money. The ISP is considered to be 'selling transit service' to the end network, thus the term transit AS.

Related Topics


- Border Gateway Protocol
- Internet Assigned Numbers Authority
- Regional Internet Registry
- Routing

External links


- [http://www.apnic.net/services/asn_guide.html ASN Resource Guide] Category:Internet architecture

Exterior Gateway Protocol

The Exterior Gateway Protocol (EGP) is a routing protocol for the Internet originally specified in 1982 by Eric C. Rosen of Bolt, Beranek and Newman, and David L. Mills. It was first described in [http://www.faqs.org/rfcs/rfc827.html RFC 827] and formally specified in [http://www.faqs.org/rfcs/rfc904.html RFC 904] (1984). EGP is a type of path vector protocol. During the early days of the Internet, an Exterior Gateway Protocol, EGP version 3, was used to interconnect autonomous systems. EGP3 should not be confused with EGPs in general. Currently, BGP is the accepted standard for Internet routing and has essentially replaced the more limited EGP3. Category:Internet protocols Category:Internet standards Category:Routing protocols

Distance-vector routing protocol

A distance-vector routing protocol is a routing protocol used in routing of packet-switched networks in computer communications, as in for example the Routing Information Protocol for Internet traffic. They use the Bellman-Ford algorithm to calculate paths. Examples of distance-vector routing protocols include RIPv1 or 2 and IGRP.

Workings

The distance-vector routing protocol assumes a network connected through several routers, each of which is connected to two or more computer networks. Each network may be connected to one or more routers. The description below describes a very simple distance-vector routing protocol: #In the first stages, the router makes a list of which networks it can reach, and how many hops it will cost. In the outset this will be the two or more networks to which this router is connected. The number of hops for these networks will be 1. This table is called a routing table. #Periodically (typically every 30 seconds) the routing table is shared with other routers on each of the connected networks via some specified inter-router protocol. These routers will add 1 to every hop-count in the table, as it associates a hop cost of 1 for reaching the router that sent the table. This information is just shared inbetween physically connected routers ("neighbors"), so routers on other networks are not reached by the new routing tables yet. #A new routing table is constructed based on the directly configured network interfaces, as before, with the addition of the new information received from other routers. The hop-count is used as a cost measure for each path. The table also contains a column stating which router offered this hop count, so that the router knows who is next in line for reaching a certain network. # Bad routing paths are then purged from the new routing table. If two identical paths to the same network exists, only the one with the smallest hop-count is kept. When the new table has been cleaned up, it may be used to replace the existing routing table used for packet forwarding. #The new routing table is then communicated to all neighbors of this router. This way the routing information will spread and eventually all routers know the routing path to each network, which router it shall use to reach this network, and to which router it shall route next.

Advantages and disadvantages

Distance-vector routing protocols are simple and efficient in small networks, and require little, if any management. However, they do not scale well, and have poor convergence properties, which has led to the development of more complex but more scalable link-state routing protocols for use in large networks. Category:Routing protocols Category:Routing algorithms

Wikipedia:Votes for deletion/J-Revolution.com

This page is an archive of the proposed deletion of the article below. Further comments should be made on the appropriate discussion page (such as the article's talk page or on a Votes for Undeletion nomination). No further edits should be made to this page. The result of the debate was delete. humblefool®Deletion Reform 02:42, 3 August 2005 (UTC)

J-Revolution.com

Advertising. This entry was created by a user obviously affiliated with the subject. 66.216.68.28 15:55, 18 July 2005 (UTC)
- Yes it was, but we are making it a factual encyclopedia artical, give us a few minutes. Jrev :Even if it weren't advertising, then it is still not notable or encyclopedic. --66.216.68.28 16:05, 18 July 2005 (UTC) :That's why I said to wait, we are in the process of writing a page for it. Jrev ::The subject isn't going to become any more notable in a few minutes. But whatever, let wikipedia decide who is right. --66.216.68.28 16:05, 18 July 2005 (UTC)
- Delete, advertising a non-notable website. --KFP 16:23, 18 July 2005 (UTC)
- Delete. Vanity, self-promotion, not notable. Wikipedia is not a web directory. AиDя01DTALKEMAIL 16:51, July 18, 2005 (UTC)
- Keep. I see nothing wrong with it. It's not a bias article, and never actually offers a link to the site in question. --100%MoreAwesomeThanYou 17:16, 18 July 2005 — (100%MoreAwesomeThanYou's 3rd edit.)
- Keep. Honestly, what is wrong with the page? It's a big site, and we ARE explaining what the site is about, and how it started... --JRev 17:25, 18 July 2005
  - When you started this page, you should have seen this text: Please do not create an article to promote yourself, a website, a product, or a business (see Wikipedia:What Wikipedia is not). AиDя01DTALKEMAIL 17:30, July 18, 2005 (UTC)
    - EXACTLY why we AREN'T promoting it. We are giving a detailed listing of how the site came about, what the site is about... not promoting it.
      - The act of merely creating the article could be seen as promotion, but let's leave that aside for the moment: "J-Revolution.com is a great source for information", "While you are there, you can learn many things", "Pulling in staffers from all over the world, J-Revolution aspires for the top", "the staff and admin have made a name for themselves on the internet for being there for the users" is all promotional language that is not appropriate for an encyclopedia. See WP:NPOV, and also Wikipedia:Importance. AиDя01DTALKEMAIL 17:47, July 18, 2005 (UTC)
      -
- Keyword: "promote." The article in question never says something like "...so go visit (Webpage name here) today! It gives a brief overview of what the site contains, and some minor background information. If, for example, Burger King only told you what their products contained, and gave a brief background of it, in an ad, I don't think they would gain many sales from that ad. A more solid argument would be that it is irrelevant or non-notable. If the act of creating that page is advertising, than the Google page needs a load of work. The Google page includes a link to their search, even though it is posted as Google Inc. Seems like a silly way to cover an ad. The article in question could use some minor editing to be appropriate, but that is not a reason to exterminate it entirely. --100%MoreAwesomeThanYou 17:54, 18 July 2005
      -
  - If POV were the only issue here, then yes, some minor editing would be fine for this article. AиDя01DTALKEMAIL 18:10, July 18, 2005 (UTC)
      -
    - That would be why I said that a more solid argument would be that it is irrelevant or non-notable. I stand by my opinion that it is notable enough to be kept. --100%MoreAwesomeThanYou 18:20, 18 July 2005 Yes, and if you notice, we say that we ASPIRE for the top, that you CAN learn many things, that we WANT to be the best, we never say we are. We are not being biased.
- Lack of importance is the main issue here, not bias. The site does not seem to be notable enough to merit an article at Wikipedia, at least not yet. --KFP 18:08, 18 July 2005 (UTC)
  - Agreed. Notability is definitely the main issue here. I was merely pointing out problems with the promotional language in the article, which is a side issue. AиDя01DTALKEMAIL 18:10, July 18, 2005 (UTC) Therefore you would be biased against the site. Saying that YOU think it isn't notable enough. To some people it is.
- Delete. You assume that others are "biased" against something they've only just heard of. That's not the case. This is (a) a non-notable website and (b) self-promotion. It's not an encyclopedia article. ---- Except from amazon.com entry: Amazon.com, Inc. (NASDAQ: AMZN) is an American electronic commerce company based in Seattle, Washington. It was one of the first major companies to sell goods over the Internet. Amazon also owns Alexa Internet, a9.com, and the Internet Movie Database (IMDb). Amazon assigns a unique identifier, the Amazon Standard Identification Number (ASIN), to each item it sells. (For books, the ASIN is the same as the item's ISBN, if it has one.) Amazon offers access to its catalog via web services, much as Google does to its search engine. In addition, a9.com provides search engine services directly on the Amazon.com site. Launched in 1995, Amazon.com began as an online book-selling company but has now branched off into many other areas, including DVDs, music CDs, computer software, video games, electronics, apparel, furniture, and more. ---- This is quite similitar to the j-revolution definition. Look back at it. J-Revolution is a major site in the anime world that is growing more known each day. When people see J-Rev or J-Revolution, they're either curious or already know what it means. Having the definition here shows inquisitive minds what the site is about.
- Delete. Not notable. Shanes 19:19, 18 July 2005 (UTC)
- Delete or Redirect to User:Jrev. There are a few hundred google hits for the site, once after sorting out some extemporaneous material. The site has an Alexa rank of 209,094, which is a little under the usual bar set for including purely web-based material. --Icelight 19:31, July 18, 2005 (UTC)
  - No redirects from article space to user space, please. See Wikipedia:Redirects for deletion. --KFP 20:12, 18 July 2005 (UTC)
    - Sorry, meant to type Merge, as that user is the company. Got distracted while typing. Icelight 22:40, July 18, 2005 (UTC)
      - Merge implies a redirect. AиDя01DTALKEMAIL 23:18, July 18, 2005 (UTC)
- Delete nn. That Alexa rank is waaaaaaaaaaaaaaaaaaaaaaaaaaaaay below what would normally be considered notable. -Splash 20:17, 18 July 2005 (UTC)
- Delete. The user admitted that the site had only been operating since April 2005, with around 300 members to date. Give it a year or so to see whether the site becomes as popular/notable as it ASPIREs to become. Regardless, the article needs to be edited to follow an encyclopedic format; right now some sections read like a company mission statement.--Madchester 21:03, July 18, 2005 (UTC)
- Delete no evidence that this is a notable website. Sorry. CDC (talk) 22:38, 18 July 2005 (UTC)
- Delete, non-notable website. Dcarrano 23:12, July 18, 2005 (UTC)
- Delete nn website vanity. --Etacar11 00:36, 19 July 2005 (UTC)
- Deletio vanitosis. --FOo 03:56, 19 July 2005 (UTC)
- Delete, non-notable website ([http://www.alexa.com/data/details/?url=www.J-Revolution.com Alexa ranking 209,094]). Also the site appears to be down at the moment. --Stormie 03:57, July 19, 2005 (UTC)
- Delete advertising for a non notable website. JamesBurns 07:54, 19 July 2005 (UTC)
- Delete - advertising (as shown by promotional rhetoric) and vanity at the same time, since the contributor practically admits that he is promoting his site. Not to mention that WP is NOT web directory. I hope he is not recruiting for sock- or meatpuppets. Skysmith 08:47, 19 July 2005 (UTC)
  - Note that , who has been involved with this VFD, blanked it. He may try again - Skysmith 09:43, 19 July 2005 (UTC)
- Delete. Move it to the user page until notability is established. Bart133 (t) 16:45, 19 July 2005 (UTC)
- Delete. It's hard to draw a comparison between a well-known company (like Amazon) with a recently-created site. Even if the article were perfect, it's still not notable yet. --Titoxd 01:54, 20 July 2005 (UTC)
- Delete. Ad. Binadot 03:25, 21 July 2005 (UTC) :The above discussion is preserved as an archive of the debate. Please do not modify it. Subsequent comments should be made on the appropriate discussion page (such as the article's talk page or in an undeletion request). No further edits should be made to this page.


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