Re: Question on the meaning of tunneling [7:6136]
In my opinion, a tunnel is when you take one packet and encapsulate it with an additional routing protocol header in order to pass it over a transit network transparently. So, DLSW uses tunnels, GRE tunnels are obviously tunnels, PIM register messages are tunnels, etc. That's just a brief definition but it works for me. At 01:19 PM 5/28/01, you wrote: Question came up on the CCIE group revolving around the meaning of the term tunnel I think I am seeing where the author of the below quote is going. I'm wondering if one of the folks on this group might be willing to offer some insight. The question originated with someone calling an OSPF virtual link a tunnel. After some back and forth, someone offered the following (edited for brevity, and clarity): ...understand the basics of software tunneling. TUNNELING PROVIDES ALTERNATIVE TO THE NATIVE CONNECTIVITY PROCEDURE. In this case there is no physical/datalink connectivity, so connectivity is achieved through software interface. Virtual Links are not tunnels, you can't transport traffic over them, they just carry routing information. They are TUNNELING this routing information through area 1. THIS IS THE PRINCIPLE OF TUNNELLING. IT IS NOT ONLY APPLICATION DATA THAT IS TUNNELED : IN THIS CASE ROUTING UPDATES ARE BEING TUNNELED! you seem to know only Cisco exam material (tunnel interfaces) please read further afield and grasp generics/basics of software programming principles, Can anyone offer further clarification here? Thanks Chuck One IOS to forward them all. One IOS to find them. One IOS to summarize them all And in the routing table bind them. -JRR Chambers- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6139t=6136 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Question on the meaning of tunneling [7:6136]
Question came up on the CCIE group revolving around the meaning of the term tunnel I think I am seeing where the author of the below quote is going. I'm wondering if one of the folks on this group might be willing to offer some insight. The question originated with someone calling an OSPF virtual link a tunnel. After some back and forth, someone offered the following (edited for brevity, and clarity): ...understand the basics of software tunneling. TUNNELING PROVIDES ALTERNATIVE TO THE NATIVE CONNECTIVITY PROCEDURE. In this case there is no physical/datalink connectivity, so connectivity is achieved through software interface. Virtual Links are not tunnels, you can't transport traffic over them, they just carry routing information. They are TUNNELING this routing information through area 1. THIS IS THE PRINCIPLE OF TUNNELLING. IT IS NOT ONLY APPLICATION DATA THAT IS TUNNELED : IN THIS CASE ROUTING UPDATES ARE BEING TUNNELED! you seem to know only Cisco exam material (tunnel interfaces) please read further afield and grasp generics/basics of software programming principles, Can anyone offer further clarification here? In the most general sense, a tunnel is a means of taking a protocol data unit payload of OSI layer N of protocol family P1: (N,P1)-PDU, and transmitting it with a delivery header at layer M of protocol family P2. What is actually transmitted is, minimally, a (N,P1)-PDU encapsulated in a (M,P2)-PDU. There may be a shim between the end of the delivery header and the beginning of the payload header; there's no good OSIRM term for the shim. FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Question on the meaning of tunneling [7:6136]
Howard C. Berkowitz wrote: In the most general sense, a tunnel is a means of taking a protocol data unit payload of OSI layer N of protocol family P1: (N,P1)-PDU, and transmitting it with a delivery header at layer M of protocol family P2. What is actually transmitted is, minimally, a (N,P1)-PDU encapsulated in a (M,P2)-PDU. There may be a shim between the end of the delivery header and the beginning of the payload header; there's no good OSIRM term for the shim. In a slightly less mathematical explanation: Think about the encapsulation steps while traveling down the stack. Are one or more layers repeated? If so, then tunneling is involved. Yeah, that's simplistic. - Marty Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6166t=6136 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Question on the meaning of tunneling [7:6136]
Tunneling, in general, is taking data (whether user data, routing information, etc), encapsulating it in another protocol for travel (i.e. TCP/IP), and sending it to a destination where the other end unwraps the encapsulation and then uses the data (whether user data, routing information, etc). DONE! It's obvious that the quotes below are written specifically talking about OSPF Virtual Links, which basically is for routing formation only. However, DLSW tunnels, STUN and BSTUN tunnels simply take the SNA (or Sync or Bi-Sync serial) frames, encapsulate them in IP packets, route them through the internetwork, and then gets rid of the IP encapsulation and uses the SNA/Synch/Bi-Synch frames as they were transmitted from the original source. DLSW is a major tunneling system used to connect mainframes because you can stick a router on the token ring connected to each mainframe, and as long as there is an IP route between the 2 routers (and they know each others IP address), they establish a tunnel, and the two mainframes think they're directly connected (actually they think they're on rings that are connected). On another note, the statement that there is no physical/datalink connectivity, although true, is kinda misleading. In the case of DLSW tunnels, the routers on either end of the tunnel use TCP to provide reliable transport of the SNA traffic, and then use Local Acknowledgement to each of the mainframes, thus providing virtual datalink connectivity. As far as the mainframes are concerned, there IS a datalink connection. So, you must realize, in OSPF Virtual Links, the tunneling process only carries routing data, but other tunnels DO carry application data Mike W. Chuck Larrieu wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Question came up on the CCIE group revolving around the meaning of the term tunnel I think I am seeing where the author of the below quote is going. I'm wondering if one of the folks on this group might be willing to offer some insight. The question originated with someone calling an OSPF virtual link a tunnel. After some back and forth, someone offered the following (edited for brevity, and clarity): ...understand the basics of software tunneling. TUNNELING PROVIDES ALTERNATIVE TO THE NATIVE CONNECTIVITY PROCEDURE. In this case there is no physical/datalink connectivity, so connectivity is achieved through software interface. Virtual Links are not tunnels, you can't transport traffic over them, they just carry routing information. They are TUNNELING this routing information through area 1. THIS IS THE PRINCIPLE OF TUNNELLING. IT IS NOT ONLY APPLICATION DATA THAT IS TUNNELED : IN THIS CASE ROUTING UPDATES ARE BEING TUNNELED! you seem to know only Cisco exam material (tunnel interfaces) please read further afield and grasp generics/basics of software programming principles, Can anyone offer further clarification here? Thanks Chuck One IOS to forward them all. One IOS to find them. One IOS to summarize them all And in the routing table bind them. -JRR Chambers- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6172t=6136 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Question on the meaning of tunneling [7:6136]
Did some more research. In the context of the question, I went to the RFC to see what the source says. It occurred to me that the behaviour of virtual links must be defined in there somewhere. Sure enough, in the router LSA there is something called the V bit, which when set determines that the originator of the LSA is one endpoint of a virtual link. when two routers agree that they are the endpoints of the same virtual link, as determined by their RIDs as defined when the VL is configured, then the virtual link is established. bit V When set, the router is an endpoint of one or more fully adjacent virtual links having the described area as Transit area (V is for virtual link endpoint). In another place: Virtual links are part of the backbone, and behave as if they were unnumbered point-to-point networks between the two routers. I believe this lays to rest the question as to whether of not an OSPF virtual link is a tunnel. It is not. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Marty Adkins Sent: Monday, May 28, 2001 7:24 PM To: [EMAIL PROTECTED] Subject:Re: Question on the meaning of tunneling [7:6136] Howard C. Berkowitz wrote: In the most general sense, a tunnel is a means of taking a protocol data unit payload of OSI layer N of protocol family P1: (N,P1)-PDU, and transmitting it with a delivery header at layer M of protocol family P2. What is actually transmitted is, minimally, a (N,P1)-PDU encapsulated in a (M,P2)-PDU. There may be a shim between the end of the delivery header and the beginning of the payload header; there's no good OSIRM term for the shim. In a slightly less mathematical explanation: Think about the encapsulation steps while traveling down the stack. Are one or more layers repeated? If so, then tunneling is involved. Yeah, that's simplistic. - Marty FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6181t=6136 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Question on the meaning of tunneling [7:6136]
Virtual links are part of the backbone, and behave as if they were unnumbered point-to-point networks between the two routers. its a virtual link. its an unnumbered network. a network/segmrnt nonetheless, and that description sounds like a tunnel. it's possible im reading it out of context and misunderstanding / me goes to grab his Doyle book ..Page 464, P1, the VL is a tunnel through which packets may be routed on the optimal pathfrom one endpoint to the other. ...It would be unwise to tell god he is wrong. Doyle is the man who wrote the book, literally... - Original Message - From: Chuck Larrieu To: Sent: Tuesday, May 29, 2001 1:18 AM Subject: RE: Question on the meaning of tunneling [7:6136] Did some more research. In the context of the question, I went to the RFC to see what the source says. It occurred to me that the behaviour of virtual links must be defined in there somewhere. Sure enough, in the router LSA there is something called the V bit, which when set determines that the originator of the LSA is one endpoint of a virtual link. when two routers agree that they are the endpoints of the same virtual link, as determined by their RIDs as defined when the VL is configured, then the virtual link is established. bit V When set, the router is an endpoint of one or more fully adjacent virtual links having the described area as Transit area (V is for virtual link endpoint). In another place: Virtual links are part of the backbone, and behave as if they were unnumbered point-to-point networks between the two routers. I believe this lays to rest the question as to whether of not an OSPF virtual link is a tunnel. It is not. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Marty Adkins Sent: Monday, May 28, 2001 7:24 PM To: [EMAIL PROTECTED] Subject: Re: Question on the meaning of tunneling [7:6136] Howard C. Berkowitz wrote: In the most general sense, a tunnel is a means of taking a protocol data unit payload of OSI layer N of protocol family P1: (N,P1)-PDU, and transmitting it with a delivery header at layer M of protocol family P2. What is actually transmitted is, minimally, a (N,P1)-PDU encapsulated in a (M,P2)-PDU. There may be a shim between the end of the delivery header and the beginning of the payload header; there's no good OSIRM term for the shim. In a slightly less mathematical explanation: Think about the encapsulation steps while traveling down the stack. Are one or more layers repeated? If so, then tunneling is involved. Yeah, that's simplistic. - Marty FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6183t=6136 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Question on the meaning of tunneling [7:6136]
My quote was from the RFC, which I believe is the authoritative source. All that happens is that a particular bit in the router LSA is set, and when the two end points agree, based on the V-bit setting and the respective RID's, the virtual link is established. Jeff Doyle puts his pants on the same way you and I do. I'm sure he's made a mistake or two in his life. There are a few pages of errata to be found for his book. :- Chuck -Original Message- From: Peter I. Slow [mailto:[EMAIL PROTECTED]] Sent: Monday, May 28, 2001 10:52 PM To: Chuck Larrieu; [EMAIL PROTECTED] Subject:Re: Question on the meaning of tunneling [7:6136] Virtual links are part of the backbone, and behave as if they were unnumbered point-to-point networks between the two routers. its a virtual link. its an unnumbered network. a network/segmrnt nonetheless, and that description sounds like a tunnel. it's possible im reading it out of context and misunderstanding / me goes to grab his Doyle book ..Page 464, P1, the VL is a tunnel through which packets may be routed on the optimal pathfrom one endpoint to the other. ...It would be unwise to tell god he is wrong. Doyle is the man who wrote the book, literally... - Original Message - From: Chuck Larrieu To: Sent: Tuesday, May 29, 2001 1:18 AM Subject: RE: Question on the meaning of tunneling [7:6136] Did some more research. In the context of the question, I went to the RFC to see what the source says. It occurred to me that the behaviour of virtual links must be defined in there somewhere. Sure enough, in the router LSA there is something called the V bit, which when set determines that the originator of the LSA is one endpoint of a virtual link. when two routers agree that they are the endpoints of the same virtual link, as determined by their RIDs as defined when the VL is configured, then the virtual link is established. bit V When set, the router is an endpoint of one or more fully adjacent virtual links having the described area as Transit area (V is for virtual link endpoint). In another place: Virtual links are part of the backbone, and behave as if they were unnumbered point-to-point networks between the two routers. I believe this lays to rest the question as to whether of not an OSPF virtual link is a tunnel. It is not. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Marty Adkins Sent: Monday, May 28, 2001 7:24 PM To: [EMAIL PROTECTED] Subject: Re: Question on the meaning of tunneling [7:6136] Howard C. Berkowitz wrote: In the most general sense, a tunnel is a means of taking a protocol data unit payload of OSI layer N of protocol family P1: (N,P1)-PDU, and transmitting it with a delivery header at layer M of protocol family P2. What is actually transmitted is, minimally, a (N,P1)-PDU encapsulated in a (M,P2)-PDU. There may be a shim between the end of the delivery header and the beginning of the payload header; there's no good OSIRM term for the shim. In a slightly less mathematical explanation: Think about the encapsulation steps while traveling down the stack. Are one or more layers repeated? If so, then tunneling is involved. Yeah, that's simplistic. - Marty FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6184t=6136 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Question on the meaning of tunneling [7:6136]
ok. well my own personal idea of a tunnel is a thing that ecapsulates traffic to make it transparent to the underlying network, or vice-versa... the VL does not meet my own definition, but it is an alternate path that the traffic can take. In reality, the traffic is ROUTED along the path that you need to take to get to the opposite endpoint. I am putting one of these dumb things together to see how it really functions. ...am i correct? - Original Message - From: Chuck Larrieu To: Peter I. Slow ; Sent: Tuesday, May 29, 2001 1:54 AM Subject: RE: Question on the meaning of tunneling [7:6136] My quote was from the RFC, which I believe is the authoritative source. All that happens is that a particular bit in the router LSA is set, and when the two end points agree, based on the V-bit setting and the respective RID's, the virtual link is established. Jeff Doyle puts his pants on the same way you and I do. I'm sure he's made a mistake or two in his life. There are a few pages of errata to be found for his book. :- Chuck -Original Message- From: Peter I. Slow [mailto:[EMAIL PROTECTED]] Sent: Monday, May 28, 2001 10:52 PM To: Chuck Larrieu; [EMAIL PROTECTED] Subject: Re: Question on the meaning of tunneling [7:6136] Virtual links are part of the backbone, and behave as if they were unnumbered point-to-point networks between the two routers. its a virtual link. its an unnumbered network. a network/segmrnt nonetheless, and that description sounds like a tunnel. it's possible im reading it out of context and misunderstanding / me goes to grab his Doyle book ..Page 464, P1, the VL is a tunnel through which packets may be routed on the optimal pathfrom one endpoint to the other. ...It would be unwise to tell god he is wrong. Doyle is the man who wrote the book, literally... - Original Message - From: Chuck Larrieu To: Sent: Tuesday, May 29, 2001 1:18 AM Subject: RE: Question on the meaning of tunneling [7:6136] Did some more research. In the context of the question, I went to the RFC to see what the source says. It occurred to me that the behaviour of virtual links must be defined in there somewhere. Sure enough, in the router LSA there is something called the V bit, which when set determines that the originator of the LSA is one endpoint of a virtual link. when two routers agree that they are the endpoints of the same virtual link, as determined by their RIDs as defined when the VL is configured, then the virtual link is established. bit V When set, the router is an endpoint of one or more fully adjacent virtual links having the described area as Transit area (V is for virtual link endpoint). In another place: Virtual links are part of the backbone, and behave as if they were unnumbered point-to-point networks between the two routers. I believe this lays to rest the question as to whether of not an OSPF virtual link is a tunnel. It is not. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Marty Adkins Sent: Monday, May 28, 2001 7:24 PM To: [EMAIL PROTECTED] Subject: Re: Question on the meaning of tunneling [7:6136] Howard C. Berkowitz wrote: In the most general sense, a tunnel is a means of taking a protocol data unit payload of OSI layer N of protocol family P1: (N,P1)-PDU, and transmitting it with a delivery header at layer M of protocol family P2. What is actually transmitted is, minimally, a (N,P1)-PDU encapsulated in a (M,P2)-PDU. There may be a shim between the end of the delivery header and the beginning of the payload header; there's no good OSIRM term for the shim. In a slightly less mathematical explanation: Think about the encapsulation steps while traveling down the stack. Are one or more layers repeated? If so, then tunneling is involved. Yeah, that's simplistic. - Marty FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6186t=6136 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
