Re: Token ring Question. [7:44805]
A router is being used as a transparent bridge between a Token Ring network and an Ethernet network. Host X on the Token ring sends a packet to Host Y on the Ethernet. What would the source MAC address on the Ethernet Host ? does anyone know the answer? thank you. Cj - Original Message - From: Reza Sharifi To: Sent: Thursday, May 23, 2002 5:30 PM Subject: Re: Token ring Question. [7:44805] Ivan, Take a look at the subject (CCIE written question) that Dennis responded to on May 20. He is a great source for this group. Thanks Reza Ivan wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi all, I have a interest question, doesn't any one know the answer? A router is being used as a translation bridge between a Token Ring network and an Ethernet network. Host X on the Token ring sends a packet to Host Y on the Ethernet. The soursce MAC address of the packet is 400.a089.0002. How would the MAC address be interpreted in an Ethernet environment? does anyone know the answer? thank you. Ivan Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44943t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Token ring Question. [7:44805]
you can do transparent bridging between Token Ring and Ethernet. It requires a Translational Bridging.. See the following URL: (watch for wrap) http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/mmbridge.htm Mike W. 2504s wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... A router is being used as a transparent bridge between a Token Ring network and an Ethernet network. Host X on the Token ring sends a packet to Host Y on the Ethernet. What would the source MAC address on the Ethernet Host ? does anyone know the answer? thank you. Cj Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=45000t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Token ring Question. [7:44805]
Hi Ivan, Mac addresses only have local significance. So for your scenario, host X sends a packet with it's own MAC address as the source and the router TR interface as the destination MAC address. The router then rebuilds the packet and sends it out the ethernet interface with the Ethernet interface as the source MAc address and host Y as the destination MAC address. Hth, Crestion Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44809t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Token ring Question. [7:44805]
This is achieved by bit swapping. I do not know the complete ins and outs of it but I has attached a URL which is a bit swapping tool which can be used to verify translation. http://www.cisco.com/cgi-bin/Support/Bitswap/bitswap.pl Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44835t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Token ring Question. [7:44805]
He said the router is acting as a translation (sic) bridge. So the router (bridge) address does not come into play. The router (bridge) translates the non-canonical TR address to a canonical Ethernet address. The bridge reverses the bits in each byte of the address. We have had many discussions on how to do this. It's as simple as writing your name backwards. For example, let's say one byte was 4A in hex. Put that in binary, one digit at a time. 4A 0100 1010 Now write it backwards: 0101 0010 Put it back in hex: 52 If this seems mysterious or difficult to apply in a generic fashion to any hex representation of a byte, then it's not time yet to go for CCIE. Priscilla At 08:20 AM 5/23/02, C restion wrote: Hi Ivan, Mac addresses only have local significance. So for your scenario, host X sends a packet with it's own MAC address as the source and the router TR interface as the destination MAC address. The router then rebuilds the packet and sends it out the ethernet interface with the Ethernet interface as the source MAc address and host Y as the destination MAC address. Hth, Crestion Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44842t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Token ring Question. [7:44805]
At 07:25 AM 5/23/02, Ivan wrote: Hi all, I have a interest question, doesn't any one know the answer? A router is being used as a translation bridge between a Token Ring network and an Ethernet network. Host X on the Token ring sends a packet to Host Y on the Ethernet. The soursce MAC address of the packet is 400.a089.0002. That's not a valid address. A MAC address is 48 bits or 6 bytes. In hex a byte is written with 2 digits. So the address must have 12 digits. I assume you are missing a 0 and that you meant to say: 4000.a089.0002 The bridge will translate the non-canonical address to canonical (see my other message and numerous other messages on that computing 101 topic). On the other hand, maybe the question expects you to know these other details: The first byte of that address in binary is: 0100 Token Ring transmits the most significant bit first. (the one in the 2^7 position). IEEE says that the first bit transmitted is the Specific/Group bit. (A group address is used for multicast and broadcast). 0 = Specific 1 = Group So this is a specific address. No problem. Ethernet can handle that (and could handle a multicast or broadcast too, of course.) IEEE says that the second bit transmitted is the Globally Administered/Locally Administered bit. 0 = Global 1 = Local So this is a locally-administered address. Although IEEE 802.3 (Ethernet) does officially support locally-administered addresses, they aren't often used on Ethernet. So that's a minor issue. The second byte is IEEE 802.5 (Token Ring) says that the least significant bit of the second byte is the Functional/Non Functional address. IEEE 802.3 (Ethernet) does not say this and does not support functional addresses. 0 = Functional 1 = Non functional So here we have a slightly more interesting issue. This is a functional address. Ethernet won't recognize that it's a functional address, however. From a troubleshooting viewpoint, you would want to figure out what function this was supposed to carry out on the Token Ring side. Whatever it was, it's not going to also get carried out on the Ethernet side. For most functional addresses, this isn't an issue. The well-known ones are used for purposes such as: Sending to the active monitor (which doesn't exist on Ethernet) Sending to the ring parameter server (which doesn't exist on Ethernet) Sending to LAN manager (which doesn't exist on Ethernet) etc. You get the picture This particular address is one that I don't recognize though. It may be used for a proprietary (non-standard) function on the Token Ring side. Perhaps you are expected to know these sorts of things to answer this question correctly. Priscilla How would the MAC address be interpreted in an Ethernet environment? does anyone know the answer? thank you. Ivan Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44849t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Token ring Question. [7:44805]
I just noticed that I misplaced the functional/non-functional bit. I hate that! ;-) The functional/non-functional bit is the most significant bit of the 3rd byte (not the least significant bit of the 2nd byte as I said before.) So, the address is: 4000.a089.0002 0100 1010 ... First bit transmitted (most significant of 1st byte) is 0 (specific) Second bit transmitted is 1 (locally-administered) Most significant bit of the third byte is 1 (non-functional) That makes more sense now that I see he was referring to a source address. A source address shouldn't be a functional address. Priscilla At 01:17 PM 5/23/02, Priscilla Oppenheimer wrote: At 07:25 AM 5/23/02, Ivan wrote: Hi all, I have a interest question, doesn't any one know the answer? A router is being used as a translation bridge between a Token Ring network and an Ethernet network. Host X on the Token ring sends a packet to Host Y on the Ethernet. The soursce MAC address of the packet is 400.a089.0002. That's not a valid address. A MAC address is 48 bits or 6 bytes. In hex a byte is written with 2 digits. So the address must have 12 digits. I assume you are missing a 0 and that you meant to say: 4000.a089.0002 The bridge will translate the non-canonical address to canonical (see my other message and numerous other messages on that computing 101 topic). On the other hand, maybe the question expects you to know these other details: The first byte of that address in binary is: 0100 Token Ring transmits the most significant bit first. (the one in the 2^7 position). IEEE says that the first bit transmitted is the Specific/Group bit. (A group address is used for multicast and broadcast). 0 = Specific 1 = Group So this is a specific address. No problem. Ethernet can handle that (and could handle a multicast or broadcast too, of course.) IEEE says that the second bit transmitted is the Globally Administered/Locally Administered bit. 0 = Global 1 = Local So this is a locally-administered address. Although IEEE 802.3 (Ethernet) does officially support locally-administered addresses, they aren't often used on Ethernet. So that's a minor issue. The second byte is IEEE 802.5 (Token Ring) says that the least significant bit of the second byte is the Functional/Non Functional address. IEEE 802.3 (Ethernet) does not say this and does not support functional addresses. 0 = Functional 1 = Non functional So here we have a slightly more interesting issue. This is a functional address. Ethernet won't recognize that it's a functional address, however. From a troubleshooting viewpoint, you would want to figure out what function this was supposed to carry out on the Token Ring side. Whatever it was, it's not going to also get carried out on the Ethernet side. For most functional addresses, this isn't an issue. The well-known ones are used for purposes such as: Sending to the active monitor (which doesn't exist on Ethernet) Sending to the ring parameter server (which doesn't exist on Ethernet) Sending to LAN manager (which doesn't exist on Ethernet) etc. You get the picture This particular address is one that I don't recognize though. It may be used for a proprietary (non-standard) function on the Token Ring side. Perhaps you are expected to know these sorts of things to answer this question correctly. Priscilla How would the MAC address be interpreted in an Ethernet environment? does anyone know the answer? thank you. Ivan Priscilla Oppenheimer http://www.priscilla.com Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44852t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Token ring Question. [7:44805]
This is correct if the router is acting as a router but when the router is bridging, this is no longer true. To answer your question, Ivan, you would simply perform bitswapping on the TR MAC to find the ethernet equivalent. There were a series of posts on this topic (some by me) that specifically lay out this process in both Hex and binary. Do a quick search for messages from the past couple of weeks for the work 'bitswapping' and you'll find them. HTH, Mike W. C restion wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi Ivan, Mac addresses only have local significance. So for your scenario, host X sends a packet with it's own MAC address as the source and the router TR interface as the destination MAC address. The router then rebuilds the packet and sends it out the ethernet interface with the Ethernet interface as the source MAc address and host Y as the destination MAC address. Hth, Crestion Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44889t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Token ring Question. [7:44805]
Priscilla Oppenheimer wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... If this seems mysterious or difficult to apply in a generic fashion to any hex representation of a byte, then it's not time yet to go for CCIE. Thank you for verifying my feelings about this. As you may, or may not, have seen the conversations on this topic of late, I may have stepped on peoples toes a bit with my attitude toward learning binary, but i still stand by what I said.. (which, in case you missed out (LOL), was Learn binary. computers are binary. networks are binary this is not rocket science!! =) Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44891t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Token ring Question. [7:44805]
Ivan, Take a look at the subject (CCIE written question) that Dennis responded to on May 20. He is a great source for this group. Thanks Reza Ivan wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi all, I have a interest question, doesn't any one know the answer? A router is being used as a translation bridge between a Token Ring network and an Ethernet network. Host X on the Token ring sends a packet to Host Y on the Ethernet. The soursce MAC address of the packet is 400.a089.0002. How would the MAC address be interpreted in an Ethernet environment? does anyone know the answer? thank you. Ivan Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44896t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Token ring Question. [7:44805]
I'm with you 100% on this. I said that bit swapping is as easy as writing your name backwards. Maybe that's a bit of an exaggeration, so to speak, because you do have to do hex to binary and back, but only for a four-digit binary number. So it's as easy as writing your name backwards in Pig Latin. If people don't find it that easy, they should start with CCNA (or a basic math class or a how do computers work class). There's nothing wrong with that. If people can really get CCIE despite finding this difficult, or only because they memorized some charts, I'd be surprised. Don't waste time trying for CCIE. Start with the basics. That would be my advice anyway. Priscilla At 05:19 PM 5/23/02, Michael L. Williams wrote: Priscilla Oppenheimer wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... If this seems mysterious or difficult to apply in a generic fashion to any hex representation of a byte, then it's not time yet to go for CCIE. Thank you for verifying my feelings about this. As you may, or may not, have seen the conversations on this topic of late, I may have stepped on peoples toes a bit with my attitude toward learning binary, but i still stand by what I said.. (which, in case you missed out (LOL), was Learn binary. computers are binary. networks are binary this is not rocket science!! =) Mike W. Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44898t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Token ring Question. [7:44805]
This particular address is one that I don't recognize though. It may be used for a proprietary (non-standard) function on the Token Ring side. 4000.. addresses are often used for mainframe connectivity - TIC addresses, APPN end nodes, etc. I don't know whether there is any particular reason for this, but it seems to be a fairly widespread convention. JMcL - Forwarded by Jenny Mcleod/NSO/CSDA on 24/05/2002 08:59 am - Priscilla Oppenheimer Sent by: [EMAIL PROTECTED] 24/05/2002 03:17 am Please respond to Priscilla Oppenheimer To: [EMAIL PROTECTED] cc: Subject:Re: Token ring Question. [7:44805] Is this part of a business decision process?: At 07:25 AM 5/23/02, Ivan wrote: Hi all, I have a interest question, doesn't any one know the answer? A router is being used as a translation bridge between a Token Ring network and an Ethernet network. Host X on the Token ring sends a packet to Host Y on the Ethernet. The soursce MAC address of the packet is 400.a089.0002. That's not a valid address. A MAC address is 48 bits or 6 bytes. In hex a byte is written with 2 digits. So the address must have 12 digits. I assume you are missing a 0 and that you meant to say: 4000.a089.0002 The bridge will translate the non-canonical address to canonical (see my other message and numerous other messages on that computing 101 topic). On the other hand, maybe the question expects you to know these other details: The first byte of that address in binary is: 0100 Token Ring transmits the most significant bit first. (the one in the 2^7 position). IEEE says that the first bit transmitted is the Specific/Group bit. (A group address is used for multicast and broadcast). 0 = Specific 1 = Group So this is a specific address. No problem. Ethernet can handle that (and could handle a multicast or broadcast too, of course.) IEEE says that the second bit transmitted is the Globally Administered/Locally Administered bit. 0 = Global 1 = Local So this is a locally-administered address. Although IEEE 802.3 (Ethernet) does officially support locally-administered addresses, they aren't often used on Ethernet. So that's a minor issue. The second byte is IEEE 802.5 (Token Ring) says that the least significant bit of the second byte is the Functional/Non Functional address. IEEE 802.3 (Ethernet) does not say this and does not support functional addresses. 0 = Functional 1 = Non functional So here we have a slightly more interesting issue. This is a functional address. Ethernet won't recognize that it's a functional address, however. From a troubleshooting viewpoint, you would want to figure out what function this was supposed to carry out on the Token Ring side. Whatever it was, it's not going to also get carried out on the Ethernet side. For most functional addresses, this isn't an issue. The well-known ones are used for purposes such as: Sending to the active monitor (which doesn't exist on Ethernet) Sending to the ring parameter server (which doesn't exist on Ethernet) Sending to LAN manager (which doesn't exist on Ethernet) etc. You get the picture This particular address is one that I don't recognize though. It may be used for a proprietary (non-standard) function on the Token Ring side. Perhaps you are expected to know these sorts of things to answer this question correctly. Priscilla How would the MAC address be interpreted in an Ethernet environment? does anyone know the answer? thank you. Ivan Priscilla Oppenheimer http://www.priscilla.com Important: This e-mail is intended for the use of the addressee and may contain information that is confidential, commercially valuable or subject to legal or parliamentary privilege. If you are not the intended recipient you are notified that any review, re-transmission, disclosure, use or dissemination of this communication is strictly prohibited by several Commonwealth Acts of Parliament. If you have received this communication in error please notify the sender immediately and delete all copies of this transmission together with any attachments. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44902t=44805 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Token ring Question. [7:44805]
At 07:03 PM 5/23/02, [EMAIL PROTECTED] wrote: This particular address is one that I don't recognize though. It may be used for a proprietary (non-standard) function on the Token Ring side. 4000.. addresses are often used for mainframe connectivity - TIC addresses, APPN end nodes, etc. I don't know whether there is any particular reason for this, but it seems to be a fairly widespread convention. Yes. An address that starts with 40 is locally-administered. Having locally-administered addresses makes life easier for VTAM on a mainframe, from what I understand. (VTAM used to assume phone numbers, for one thing, so addresses with hex letters in them weren't allowed). I think it was VTAM anyway. At first I thought the address was also a functional address. Most functional addresses are well known. But I was off by a bit. It's not a functional address. Token Ring. You gotta love it! ;-) Priscilla JMcL - Forwarded by Jenny Mcleod/NSO/CSDA on 24/05/2002 08:59 am - Priscilla Oppenheimer Sent by: [EMAIL PROTECTED] 24/05/2002 03:17 am Please respond to Priscilla Oppenheimer To: [EMAIL PROTECTED] cc: Subject:Re: Token ring Question. [7:44805] Is this part of a business decision process?: At 07:25 AM 5/23/02, Ivan wrote: Hi all, I have a interest question, doesn't any one know the answer? A router is being used as a translation bridge between a Token Ring network and an Ethernet network. Host X on the Token ring sends a packet to Host Y on the Ethernet. The soursce MAC address of the packet is 400.a089.0002. That's not a valid address. A MAC address is 48 bits or 6 bytes. In hex a byte is written with 2 digits. So the address must have 12 digits. I assume you are missing a 0 and that you meant to say: 4000.a089.0002 The bridge will translate the non-canonical address to canonical (see my other message and numerous other messages on that computing 101 topic). On the other hand, maybe the question expects you to know these other details: The first byte of that address in binary is: 0100 Token Ring transmits the most significant bit first. (the one in the 2^7 position). IEEE says that the first bit transmitted is the Specific/Group bit. (A group address is used for multicast and broadcast). 0 = Specific 1 = Group So this is a specific address. No problem. Ethernet can handle that (and could handle a multicast or broadcast too, of course.) IEEE says that the second bit transmitted is the Globally Administered/Locally Administered bit. 0 = Global 1 = Local So this is a locally-administered address. Although IEEE 802.3 (Ethernet) does officially support locally-administered addresses, they aren't often used on Ethernet. So that's a minor issue. The second byte is IEEE 802.5 (Token Ring) says that the least significant bit of the second byte is the Functional/Non Functional address. IEEE 802.3 (Ethernet) does not say this and does not support functional addresses. 0 = Functional 1 = Non functional So here we have a slightly more interesting issue. This is a functional address. Ethernet won't recognize that it's a functional address, however. From a troubleshooting viewpoint, you would want to figure out what function this was supposed to carry out on the Token Ring side. Whatever it was, it's not going to also get carried out on the Ethernet side. For most functional addresses, this isn't an issue. The well-known ones are used for purposes such as: Sending to the active monitor (which doesn't exist on Ethernet) Sending to the ring parameter server (which doesn't exist on Ethernet) Sending to LAN manager (which doesn't exist on Ethernet) etc. You get the picture This particular address is one that I don't recognize though. It may be used for a proprietary (non-standard) function on the Token Ring side. Perhaps you are expected to know these sorts of things to answer this question correctly. Priscilla How would the MAC address be interpreted in an Ethernet environment? does anyone know the answer? thank you. Ivan Priscilla Oppenheimer http://www.priscilla.com Important: This e-mail is intended for the use of the addressee and may contain information that is confidential, commercially valuable or subject to legal or parliamentary privilege. If you are not the intended recipient you are notified that any review, re-transmission, disclosure, use or dissemination of this communication is strictly prohibited by several Commonwealth Acts of Parliament. If you have received this communication in error please notify the sender immediately and delete all copies of this transmission together with any attachments. Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=44905t=44805 -- FAQ, list archives, and subscription info: http
