RIP and OSPF, which layer?

MrXpert

i was having a debate with someone about rip and ospf and what layer of the OSI they live in. My argument was that they are likely to be layer 3 network protocols because of the fact they enable routing using logical addresses. My friend says they are application protocols because the user interacts with them. I can kinda see his point. We tried looking at various sources for help to settle this but it seems very unclear.

Can anyone help please?

MrRyte

MrXpert wrote: »

My friend says they are application protocols because the user interacts with them.....

And HOW EXACTLY does the end user interact or use RIP, OSPF or any other routing protocol?

I think that the answer is obvious....

hiddenknight821

MrXpert wrote: »

Can anyone help please?

You got to be joking. It's a silly debate and you're asking us for help?! This is not some tag-team wrestling. Looks like both of you need go back to the books and review on OSI layer.

networker050184

MrRyte wrote: »

And HOW EXACTLY does the end user interact or use RIP, OSPF or any other routing protocol?

The end user doesn't, but someone configures them, apply policy etc. The same way you interact with any other application.

Its really a debatable question. Some people say application, some say network. RIP for example uses UDP for communication. Does that make it an application? Guess its up to interpretation.

SdotLow

We tried looking at various sources for help to settle this but it seems very unclear.

You didn't look very hard. You could have gotten the answer on Wikipedia.

An application layer protocol is something like Telnet, HTTP, or FTP. Something communicates with an application, so to speak. OSPF and RIP are never seen by an application, or the application layer.

With that being said, you're posting in the CCENT/CCNA forums about a very easy question that can be found in your study book(s). I'd suggest looking there.

networker050184

SdotLow wrote: »

You didn't look very hard. You could have gotten the answer on Wikipedia.

An application layer protocol is something like Telnet, HTTP, or FTP. Something communicates with an application, so to speak. OSPF and RIP are never seen by an application, or the application layer.

With that being said, you're posting in the CCENT/CCNA forums about a very easy question that can be found in your study book(s). I'd suggest looking there.

Its not that straight forward. Why would RIP or BGP not be considered and application like Telnet?

SdotLow

networker050184 wrote: »

The end user doesn't, but someone configures them, apply policy etc. The same way you interact with any other application.

Its really a debatable question. Some people say application, some say network. RIP for example uses UDP for communication. Does that make it an application? Guess its up to interpretation.

You're obviously much more read on Cisco than I, but I don't see how either could be considered an application layer protocol, or even interpreted to be (maybe it's just the level of literature I'm reading currently and they switch it up in the CCNP track?). I know it is implicitly stated in the ICND1 and ICND2 books that RIP/OSPF/EIGRP are layer 3 protocols and Frame Relay / ATM are layer 2 protocols.

By following the logic that because they are configured they are an application layer protocol, than Frame Relay, PPP, CHAP, and IP could all be considered Layer 7 protocols.

SdotLow

networker050184 wrote: »

Its not that straight forward. Why would RIP or BGP not be considered and application like Telnet?

Telnet isn't an application, it's a protocol. Putty and tera term are applications that interface with the telnet protocol, like they do for SSH.

I would assume they wouldn't be considered because you're just altering the state of the protocol. Does changing an IP address make IP an application layer protocol?

networker050184

SdotLow wrote: »

You're obviously much more read on Cisco than I, but I don't see how either could be considered an application layer protocol, or even interpreted to be (maybe it's just the level of literature I'm reading currently and they switch it up in the CCNP track?). I know it is implicitly stated in the ICND1 and ICND2 books that RIP/OSPF/EIGRP are layer 3 protocols and Frame Relay / ATM are layer 2 protocols.

By following the logic that because they are configured they are an application layer protocol, than Frame Relay, PPP, CHAP, and IP could all be considered Layer 7 protocols.

RIP and BGP use UDP/TCP just like FTP. They exchange information that's used by Layer 3 of the OSI model sure, but you can use FTP to send some routes into a UNIX based device to populate the routing table also. Does that make FTP a layer 3 protocol in that instance?

OSPF/EIGRP do not use a data layer protocol for establishing a session, they work directly over layer 3 so it makes a lot more sense when speaking of these protocols.

If it were a test I'd go wtih layer 3, but its just a model. Everything doesn't exactly fit into it perfectly.

networker050184

SdotLow wrote: »

Telnet isn't an application, it's a protocol. Putty and tera term are applications that interface with the telnet protocol, like they do for SSH.

I would assume they wouldn't be considered because you're just altering the state of the protocol. Does changing an IP address make IP an application layer protocol?

Yep, you are correct, but you can see where the lines get blurry. Everything doesn't follow the model perfectly.

SdotLow

networker050184 wrote: »

RIP and BGP use UDP/TCP just like FTP. They exchange information that's used by Layer 3 of the OSI model sure, but you can use FTP to send some routes into a UNIX based device to populate the routing table also. Does that make FTP a layer 3 protocol in that instance?

OSPF/EIGRP do not use a data layer protocol for establishing a session, they work directly over layer 3 so it makes a lot more sense when speaking of these protocols.

If it were a test I'd go wtih layer 3, but its just a model. Everything doesn't exactly fit into it perfectly.

Doesn't everything use TCP/UDP though? Isn't the relation to the specific protocol stop where the protocol's use stops?

I mean, OSPF and RIP are used to route packets from router X to router Z, they have no use beyond that point. Their use is stripped off at layer 3, which is why they would be considered a layer 3 protocol - no?

hiddenknight821

networker050184 wrote: »

The end user doesn't, but someone configures them, apply policy etc. The same way you interact with any other application.

Its really a debatable question. Some people say application, some say network. RIP for example uses UDP for communication. Does that make it an application? Guess its up to interpretation.

If that's true, then I could flare up a discussion that a MAC address should be at the application layer, because I can spoof MAC address. Heck, I even interact with a physical layer almost everyday in my life. People who make patch cables would probably want to say that they view their work as if it's being done on application layer.

But let's get serious. Are you actually serious that this is debatable? I don't give a bull if an CCIE say it's an application layer protocol just because he/she has to configure and implement policies. I just don't see how it trickle down to the presentation, session, transport layer and so forth. Please elaborate more on this, so I can see how this is debatable, because I'm still not convinced that this is debatable.

networker050184

SdotLow wrote: »

Doesn't everything use TCP/UDP though? Isn't the relation to the specific protocol stop where the protocol's use stops?

I mean, OSPF and RIP are used to route packets from router X to router Z, they have no use beyond that point. Their use is stripped off at layer 3, which is why they would be considered a layer 3 protocol - no?

OSPF and EIGRP do not use TCP or UDP. They communicate directly over IP, protocol number 89 and 90 I believe, but don't quote me on that.

I'd personally refer to BGP/RIP as an application ran by the router to populate the routing table. OSPF/EIGRP I'd consider the same though the running directly over layer 3 makes the line a bit more blurred IMO.

SdotLow

networker050184 wrote: »

OSPF and EIGRP do not use TCP or UDP. They communicate directly over IP, protocol number 89 and 90 I believe, but don't quote me on that.

Ok, well that seems a bit above my knowledge level, lol.

I did want to point something out though...

RIP and BGP use UDP/TCP just like FTP.

FTP is used entirely for the end user, which makes it an application layer protocol. The purpose of it is transfer a file from me to you. Routing protocols are used specificly between routers, which is why it's layer 3. Am I understanding something wrong here?

networker050184

SdotLow wrote: »

Ok, well that seems a bit above my knowledge level, lol.

I did want to point something out though...



FTP is used entirely for the end user, which makes it an application layer protocol. The purpose of it is transfer a file from me to you. Routing protocols are used specificly between routers, which is why it's layer 3. Am I understanding something wrong here?

No, you are understanding correctly, but just because a router uses it instead of a person does it mean its not an application? The purpose of RIP or BGP is to transfer routing information between routers. Same as transferring a file. Seems like an application to me.

What layer would you consider DNS on? I'd say its on the application layer also, but end users don't directly use it.

Good discussion either way!

creamy_stew

Haha, quite a heated discussion!

Cisco DEFINATELY considers at least IGPs to be layer 3. So, for exam purposes - answer "layer 3"

I disagree, though, and I'm glad to see others do as well

networker050184

creamy_stew wrote: »

Haha, quite a heated discussion!

Cisco DEFINATELY considers at least IGPs to be layer 3. So, for exam purposes - answer "layer 3"

I disagree, though, and I'm glad to see other do as well

And then what happens when we get into things like LDP? Is it layer 2 1/2 because it transfers label info? I think its a murky area to say the least.

SdotLow

networker050184 wrote: »

No, you are understanding correctly, but just because a router uses it instead of a person does it mean its not an application?

Yes, I believe that would be correct. Again, does having the ability to change an IP address make it an application layer? I would say that, just because you have the ability to utilize layers to dive down and augment/alter a protocol and/or how it works, does not auto-default the attributes to the top of the stack since that was your entry point to changing it.

I mean, for example - how do you change OSPF or RIP configs? You have to use a protocol to dive down into the stack to do it. An application layer protocol. You would have to use Telnet or SSH (I don't know what layer the console operates at, I'd assume it utilizes some application layer protocol I'm unaware of - someone please let me know).

The purpose of RIP or BGP is to transfer routing information between routers. Same as transferring a file. Seems like an application to me.

No, but it's not. RIP and BGP stop at the router. I mean, I could go through the process inch by inch - but you know this already.

I feel like I'm being trolled after that last comment of yours.

Edit: and from reading your last comment, I guess I'm not being trolled.

creamy_stew

networker050184 wrote: »

And then what happens when we get into things like LDP? Is it layer 2 1/2 because it transfers label info? I think its a murky area to say the least.

GraAAh! Get out of my head!

I've struggled with this as well. I got around it by saying that MPLS provides a L2 service, but LDP still runs on top of IP

networker050184

You aren't being trolled, I think its a illegitimate question to ask. I guess you are basing your case on the fact that only people use applications and not routers. I don't see it that way personally.

terryfera

While I do agree that the lines becoming blurry because in reality routing protocols are applications, according to traffic flow they do not reside at the application layer because their specific job is at the network layer.

I think the thing you need to really consider is what the end goal of the protocol/application you are looking at is. Think about it this way; what is the purpose of HTTP, FTP, telnet, etc.? They all provide information to an Application (applications reside above the Application layer) where it will be used to provide the end user with information.
What is the purpose of OSPF, EIGRP, RIP, etc.? They route packets from a source to a destination to provide connectivity between the upper-layer application protocols (well transportation protocols > session > presentation > application.. you get the idea). They never provide data to the end user unless you are configuring/troubleshooting them. In that case they provide output to telnet/ssh/console which the application on your OS displays.

The OSI model is there to describe how data flows through the network and the various protocols. Various applications will reside at the various layers to accomplish this goal. What do you think transforms the data from frames to bits on a network card? There's an App for that too

If you really want to dig deeper and understand where applications reside and how traffic flows there's one source that no one can argue with:

OSPF v2 RFC
http://www.ietf.org/rfc/rfc2328.txt

Application Layer Protocols RFC
RFC 1123 - Requirements for Internet Hosts - Application and Support

networker050184

terryfera wrote: »

What is the purpose of OSPF, EIGRP, RIP, etc.? They route packets from a source to a destination to provide connectivity between the upper-layer application protocols (well transportation protocols > session > presentation > application.. you get the idea).

Well, actually they don't do any routing. They provide the router with the information needed to populate its routing table. The code written in the router (IOS etc.) is taking care of that function, not the actual routing protocol.

SdotLow

networker050184 wrote: »

You aren't being trolled, I think its a illegitimate question to ask. I guess you are basing your case on the fact that only people use applications and not routers. I don't see it that way personally.

I think you meant to say "legitimate" question to ask.

I'm not trying to rub you the wrong way. I'm just trying to understand what you mean. I didn't view this discussion as being "heated", just a discussion.

Anyway, back to my questions! ;P

I'm basing my case on what I've been taught, and read about the OSI layers and how they work. While I know you're far more read on Cisco, and networking in general than I am, I haven't seen anything compelling to make me think an RIP or OSPF somehow becomes an application layer protocol because they can be configured.

And...

Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks.

Are you suggesting that the router is "using" IOS (which is a whole different can of worms, I'm thinking) and is therefore using an application?

networker050184

SdotLow wrote: »

I think you meant to say "legitimate" question to ask.

I'm not trying to rub you the wrong way. I'm just trying to understand what you mean. I didn't view this discussion as being "heated", just a discussion.

Damn Chrome spell checker! And no worry, not heated here. I think its a great discussion with valid points from both angles.

SdotLow wrote: »

Anyway, back to my questions! ;P

I'm basing my case on what I've been taught, and read about the OSI layers and how they work. While I know you're far more read on Cisco, and networking in general than I am, I haven't seen anything compelling to make me think an RIP or OSPF somehow becomes an application layer protocol because they can be configured.

I'd say they are an application because they are a purpose built software used to fulfill a need for people. We could always static route everything right? Or do all of the SPF calculations manually and input the routes ourselves, but why? We can write an application that can do all of that for us. Hence routing protocols as applications that are ran by a router.

And whats the first application listed here?

TCP/IP model - Wikipedia, the free encyclopedia

Forsaken_GA

I see we need to go back to basics

Internetworking Basics - DocWiki

I'm not going to opine whether or not Cisco is the authority when it comes to the OSI model, but in the context of how the OSI model applies to their exam, I accept them as an expert opinion.

And Cisco says that Application layer is closest to the user, it requires direct interaction.

Given that, then I'd say routing protocols certainly do not apply as Application layer technology. The user does not directly interact with the routing protocols, only the nodes they exchange routes with do, and that's at a lower level, any visibility

So IOS or the client we use to login to IOS in order to activate the routing protocols? Certainly applications. The routing protocols themselves? Absolutely not.

Anything else is just semantical lawyering, and if you feel your opinion is correct, you should be making that case to the ISO, ITU-T, and Cisco.

networker050184

While I agree the Cisco answer is Layer 3, I don't think the original definition of application layer has to do with strictly human interaction. I prefer this definition.

"In TCP/IP, the Application Layer contains all protocols and methods that fall into the realm of process-to-process communications across an Internet Protocol (IP) network. Application Layer methods use the underlying Transport Layer protocols to establish host-to-host connections."

That would definitely include routing protocols, no?

But yes, I can see where you are coming from in a strictly OSI sense. But I still believe routing protocols, BGP and RIP especially are applications.

ehnde

Wow guys wtf have I just read? I guess we're a little bored today!

Forsaken_GA

TCP/IP model - Wikipedia, the free encyclopedia

Oh, well, if we're sourcing Wikipedia, then by all means -

Network Layer - Wikipedia, the free encyclopedia

Arguments over, wikipedia says RIP and BGP are layer 3!

networker050184

Where would you put LDP on the OSI model? Not trying to be difficult, curious what your opinion is on that?

SdotLow

networker050184 wrote: »

While I agree the Cisco answer is Layer 3, I don't think the original definition of application layer has to do with strictly human interaction. I prefer this definition.

"In TCP/IP, the Application Layer contains all protocols and methods that fall into the realm of process-to-process communications across an Internet Protocol (IP) network. Application Layer methods use the underlying Transport Layer protocols to establish host-to-host connections."

Here's how I look at it.

When I send a file to you, it doesn't have anything to do with a routing protocol until that data hits the router. If you and I were on the same switch, that data would never be introduced to a routing protocol.

I'm struggling to see how a routing protocol interfaces with the application layer unless you're implying IOS is the reason.

But yes, I can see where you are coming from in a strictly OSI sense. But I still believe routing protocols, BGP and RIP especially are applications.

So BGP and RIP are themselves applications???

creamy_stew

Let's say I have "hub" router with static routes pointing the networks in my organization to the proper next hop.

Every 10 minutes or so, I have a script that pushes route changes to this router via tftp. This is certainly completely transparent to the end user.

Is that,then, a L3 function?

Forsaken_GA wrote: »

I see we need to go back to basics

Internetworking Basics - DocWiki

I'm not going to opine whether or not Cisco is the authority when it comes to the OSI model, but in the context of how the OSI model applies to their exam, I accept them as an expert opinion.

And Cisco says that Application layer is closest to the user, it requires direct interaction.

Given that, then I'd say routing protocols certainly do not apply as Application layer technology. The user does not directly interact with the routing protocols, only the nodes they exchange routes with do, and that's at a lower level, any visibility

So IOS or the client we use to login to IOS in order to activate the routing protocols? Certainly applications. The routing protocols themselves? Absolutely not.

Anything else is just semantical lawyering, and if you feel your opinion is correct, you should be making that case to the ISO, ITU-T, and Cisco.