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Path Vector y Link-state

Sandra Ripley
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Ante todo, disculpad por la pregunta básica en cuestion. Aunque no lo creais, tengo un lio en la cabeza precisamente por la cantidad de informacion que hay en Internet y que lo que busco concretamente lo he encontrado de diferentes maneras. Me explico.

Link-State: A la hora de compartir informacion para hacer un mapeo total de la red dentro del AS, ¿Como exactamente lo hace?
- Comparte solo la informacion de sus directamente conectados (con su state and cost) O tambien comparte la informacion de sus advertises?  --> en Internet he encontrado ambas respuestas, es por ello que estoy confundida
- A la hora de compartirlo, ¿con quien lo comparte? solo con sus vecinos o con todos los routers del AS?  
Puede ser, que la informacion este confundida porque depende de si es un update partial o full, pero es que no consigo encontrar esta aclaracion concreta (y le he preguntado a ChatGPT pero cualquiera se fia).

Path-Vector: segun tengo entendido, comparte solo sus best paths a sus vecinos,  no toda la tabla, donde incluye toda la ruta completa con el AS-Path. ¿Es esto cierto?

Agradezco humildemente cualquier informacion al respecto, tanto en español como en ingles.

Muchisimas gracias de antemano.

8 RESPUESTAS 8

Hello @Sandra Ripley 

 "Link-State: A la hora de compartir informacion para hacer un mapeo total de la red dentro del AS, ¿Como exactamente lo hace?"

 It is done by using LSA(Link state Advertisement). There will be different types of LSA. You can get all the information here

https://www.geeksforgeeks.org/link-state-advertisement-lsa/

"- Comparte solo la informacion de sus directamente conectados (con su state and cost) O tambien comparte la informacion de sus advertises?"

  we can afirm that yes, inside the same Area they will advertise not only its status but from others.

"Puede ser, que la informacion este confundida porque depende de si es un update partial o full, pero es que no consigo encontrar esta aclaracion concreta"

They will share the full routing table when forming adjacency and partial when the are already neighboor.

"Path-Vector: segun tengo entendido, comparte solo sus best paths a sus vecinos, no toda la tabla, donde incluye toda la ruta completa con el AS-Path. ¿Es esto cierto?"

You are right. Path Vector is way more complex and the privious protocol

"In a path vector protocol, a node does not just receive the distance vector for a particular destination from it neighbor; instead, a node receives the distance as well as the entire path to the destination from its neighbor"

https://www.sciencedirect.com/topics/computer-science/path-vector-protocol

 

Thank you Flavio for answering me.

I'll try to explain myself in English because I noticed I didn't make the right questions

+++ Link-state

o) I wanted to know if when a router advertises through LSA, it is only sharing its directly connected or with its advertises as well using LSA type 1. Maybe it is sending its topology table. I don't know
- Its Directly connected networks
- Directly connected + any learned routes from other routers ( in other words: OSPF database)

o) Who receives the LSA Information from the previous router? with its neighbor o with all routers in the AS?  I know it is needed when the adjacency is full, but, I think it is not the same when is an partial update or a full update.  Maybe that's there the difference.

+++ Path vector

o) Let me get this straight. Then,  when a router is sending the prefixes along with its path to get an AS?

 

This is a nightmare . I totally lost, even though I have several sources of information. 

let not confuse here
Path factor is BGP, the prefix send with all relate info like AS-Path and other attribute 
this not seen in link state (like OSPF)

MHM

Hello MHM! 

Thank you for taking the time to reply to me.

Yeah, I know that information about path-vector is for BGP and Link-State is for OSPF. Apologies if there is something in my message with this confusion where It seems that I don't know this. 

Apparently, path vector just send all prefixes with the attributes like AS-Path as you mentioned. Thank you for this confirmation.  

Link State IGP (OSPF) the router send LSA for all connect link and receive from other router, but there is boundary which is area 
router send all to only routers in same area, hence all routers in same area have same database
router do some summary when send connect and prefix learn from other router to any other router outside it area. 

MHM

I was researching on Link-State and I think I finally figured out. I would appreciate it if someone could tell me if this is correct.

1- A router initiates the process of discovery with all its interfaces (different areas and networks) and it starts sending Hello packets across these interfaces to its neighbors. This process is performed by using multicast addresses. 
2- During the different OSPF States (Down, Init, 2-Way, Exstart, Exchange, Loading and Full), Hello packets are being sent until the state 2-way. In this state, it's time to choose a DR and BDR (as long as there are over two routers) for each segment of the network.
3- When Full state is reached, routers exchange LSA Type 1 with all routers in the same OSPF area. 

Sorry in advance, I'm aware there are more procedures, states and LSA to be considered, but I could be writing all day. 

Correct except this 

3- When Full state is reached, routers exchange LSA Type 1 with all routers in the same OSPF area. <<- not only lsa1 but all lsa (1,2,3,4,5,7)' otherwise how internal router of area (not abr/asbr) know prefix.

MHM

Hello MHM,

You're totally right. It's essential to point out that other LSAs types are sent. 

Thank you for your help. I appreciate it