route field
Bookmark this page:
 Yahoo!
 Google
 Windows Live
 del.icio.us
 digg
 Netscape
|
|
Posted by vicky on June 29, 2008, 4:16 am
Please log in for more thread options is there is a necessity of route field in layer 2 switch ... please tell me ... Thanks in advance Vikrant | ||||
|
Posted by Walter Roberson on June 29, 2008, 3:42 pm
Please log in for more thread options No, there is no necessity for that. For example, it is possible to build a layer 2 switch in which every port has a dedicated "send" path to each other port (e.g., the wiring to send from port B to port D is completely different than the wiring used to send from port C to port D); and when a packet came in to a port, the port could send the packet literally simultaneously to every other port, and then each output port could discard the packets that are not destined for that output port. No routing information of any kind would have to be kept on such a layer 2 switch, as each output port would independantly decide whether the output packet was to be transmitted or not. I am not saying that this would be a *good* way to build a layer 2 switch, but your question was about whether there is a *necessity* of having some kind of "route fiele", and my example above demonstrates that it is not *necessary*. Now, it could potentially be much more *efficient* to have some kind of "route field" in real layer 2 switches -- but it is not *necessary>
Note, by the way, that in networking, the word "route" usually refers to layer 3 information. Unmanaged layer 2 switches do not need to hold any layer 3 information for basic layer 2 operations, so if you are referring to "route" in the layer 3 sense, then the answer is a flat NO. My answer about the hypothetical layer 2 switch was for the case where you might have meant "route field" more generally, such as some kind of internal table that listed MAC addresses and their associated port: my example shows that even that kind of internal table is not *necessary* in a layer 2 switch. You have been asking a lot of questions about VLANs lately, and one of your questions that I answered recently but which you did not understand (or believe?) my answer gave a scenario in which you were attempting to show that layer 2 switch must have an intra-vlan router in order to provide VLAN connectivity in single- instance STP cases. I suspect that your current question is just a rephrasing of that earlier question, and I will reinforce my answer of that time: if you use a layer 2 switch with VLANs that are restricted to particular ports, and you use a single-instance STP protocol, then your VLAN connectivity *will* break, and the breaking would be the fault of the person that configured the situation, not the fault of the layer 2 switch. Furthermore, there is no requirement that layer 2 switches support VLANs *at all*. Several times, I have noticed you get confused about the functionality that *must* be supported in -all- layer 2 switches, mixing it up with functionality that needs only to be supported in layer 2 switches that claim to have standard conformance to particular -optional- features. | ||||
|
Posted by vicky on June 30, 2008, 3:01 am
Please log in for more thread options On Jun 30, 12:42=A0am, rober...@hushmail.com (Walter Roberson) wrote:
> In article <fe9d0880-d249-44f8-af4f-75ff7b1a5...@w5g2000prd.googlegroups.c=
om>, > > > =A0 =A0is there is a necessity of route field in layer 2 switch ...
> > =A0 =A0 =A0 =A0please tell me ... >
> No, there is no necessity for that. > > For example, it is possible to build a layer 2 switch in which every > port has a dedicated "send" path to each other port (e.g., the wiring > to send from port B to port D is completely different than the wiring > used to send from port C to port D); and when a packet came in to a > port, the port could send the packet literally simultaneously to > every other port, and then each output port could discard the > packets that are not destined for that output port. No routing > information of any kind would have to be kept on such a layer 2 > switch, as each output port would independantly decide whether > the output packet was to be transmitted or not. > > I am not saying that this would be a *good* way to build a > layer 2 switch, but your question was about whether there is > a *necessity* of having some kind of "route fiele", and my example > above demonstrates that it is not *necessary*. > > Now, it could potentially be much more *efficient* to have some kind > of "route field" in real layer 2 switches -- but it is not *necessary> > > Note, by the way, that in networking, the word "route" usually > refers to layer 3 information. Unmanaged layer 2 switches do not need > to hold any layer 3 information for basic layer 2 operations, so > if you are referring to "route" in the layer 3 sense, then the > answer is a flat NO. My answer about the hypothetical layer 2 > switch was for the case where you might have meant "route field" > more generally, such as some kind of internal table that listed > MAC addresses and their associated port: my example shows that > even that kind of internal table is not *necessary* in a layer 2 switch. > > You have been asking a lot of questions about VLANs lately, and > one of your questions that I answered recently but which you did not > understand (or believe?) my answer gave a scenario in which you > were attempting to show that layer 2 switch must have > an intra-vlan router in order to provide VLAN connectivity in single- > instance STP cases. I suspect that your current question is just > a rephrasing of that earlier question, and I will reinforce my > answer of that time: if you use a layer 2 switch with VLANs that > are restricted to particular ports, and you use a single-instance STP > protocol, then your VLAN connectivity *will* break, and the breaking > would be the fault of the person that configured the situation, > not the fault of the layer 2 switch. Furthermore, there is no > requirement that layer 2 switches support VLANs *at all*. > > Several times, I have noticed you get confused about the functionality > that *must* be supported in -all- layer 2 switches, mixing it up > with functionality that needs only to be supported in layer 2 switches > that claim to have standard conformance to particular -optional- > features. ----------------------------------------------------------------------------= Thanks a lot sir, for ur wonderful reply, again i m thank ful to u that u noticing my queries , Sir according to ur reply i've something to ask .... may i....plz As u mentioned here about inter-vlan route and one of my query is related to that ..... so the functionality of inter-valn route is provided in l2 switch is only if the switch controller provide some inter-vlan supporting register support or is done without that. and route field info ia necessary in case of IGMP Snooping ,,, sir wat u say about this.... please .... Thanks Vikrant | ||||
|
Posted by vicky on June 30, 2008, 3:04 am
Please log in for more thread options On Jun 30, 12:42=A0am, rober...@hushmail.com (Walter Roberson) wrote:
> In article <fe9d0880-d249-44f8-af4f-75ff7b1a5...@w5g2000prd.googlegroups.=
com>, > > > =A0 =A0is there is a necessity of route field in layer 2 switch ...
> > =A0 =A0 =A0 =A0please tell me ... >
> No, there is no necessity for that. > > For example, it is possible to build a layer 2 switch in which every > port has a dedicated "send" path to each other port (e.g., the wiring > to send from port B to port D is completely different than the wiring > used to send from port C to port D); and when a packet came in to a > port, the port could send the packet literally simultaneously to > every other port, and then each output port could discard the > packets that are not destined for that output port. No routing > information of any kind would have to be kept on such a layer 2 > switch, as each output port would independantly decide whether > the output packet was to be transmitted or not. > > I am not saying that this would be a *good* way to build a > layer 2 switch, but your question was about whether there is > a *necessity* of having some kind of "route fiele", and my example > above demonstrates that it is not *necessary*. > > Now, it could potentially be much more *efficient* to have some kind > of "route field" in real layer 2 switches -- but it is not *necessary> > > Note, by the way, that in networking, the word "route" usually > refers to layer 3 information. Unmanaged layer 2 switches do not need > to hold any layer 3 information for basic layer 2 operations, so > if you are referring to "route" in the layer 3 sense, then the > answer is a flat NO. My answer about the hypothetical layer 2 > switch was for the case where you might have meant "route field" > more generally, such as some kind of internal table that listed > MAC addresses and their associated port: my example shows that > even that kind of internal table is not *necessary* in a layer 2 switch. > > You have been asking a lot of questions about VLANs lately, and > one of your questions that I answered recently but which you did not > understand (or believe?) my answer gave a scenario in which you > were attempting to show that layer 2 switch must have > an intra-vlan router in order to provide VLAN connectivity in single- > instance STP cases. I suspect that your current question is just > a rephrasing of that earlier question, and I will reinforce my > answer of that time: if you use a layer 2 switch with VLANs that > are restricted to particular ports, and you use a single-instance STP > protocol, then your VLAN connectivity *will* break, and the breaking > would be the fault of the person that configured the situation, > not the fault of the layer 2 switch. Furthermore, there is no > requirement that layer 2 switches support VLANs *at all*. > > Several times, I have noticed you get confused about the functionality > that *must* be supported in -all- layer 2 switches, mixing it up > with functionality that needs only to be supported in layer 2 switches > that claim to have standard conformance to particular -optional- > features. ---------------------------------------------------------------------------= ----------------------------------- Hi, Can U plz tell me about Leaky VLAN concept.... plz also provide u'r email-id for further discussion as some of my queries are .... in form of graphics here it is not possible to put that type of queries.... Thanks Vikrant | ||||
|
Posted by Walter Roberson on July 1, 2008, 5:33 am
Please log in for more thread options
>plz also provide u'r email-id for further discussion as some of my
>queries are .... in form of graphics >here it is not possible to put that type of queries.... Sorry, I would prefer to to conduct these discussions in public. My experience with switches and routers is more practical than theoretical, and is based largely upon older generations of equipment before IGMP and the like was important. As you are asking questions about newer more advanced features, it is better that my answers be in public where the people who know better can correct my mistakes. | ||||
| Similar Threads | Posted |
| route field | June 29, 2008, 4:16 am |
| Static route or NAT | January 9, 2008, 2:42 am |
| Backup-Route + Traffic | June 11, 2007, 6:09 am |
| Cisco Router route statement | November 20, 2004, 10:19 am |
| VLANs: do all switches in a route have to support it? | March 11, 2005, 1:25 am |
| 802.11 Fixed Field Elements | September 8, 2006, 4:07 pm |
| Why we need a length field in Ethernet while we don't need it in FDDI?? | January 18, 2005, 4:04 am |
| Multicast MAC in Source MAC Address Field | August 30, 2005, 5:13 pm |
| Length field in 802.3 for tagged frames | November 24, 2006, 4:02 am |
| Managed Ethernet Field Switch Provides Support for Tarrifed Wireless and Fiber-to-Premises Applications | June 21, 2005, 3:06 pm |
> please tell me ...