Re: Certificationzone White Paper ? [7:16354]
Agreed and I would add a comment. A lot of people assume that cut-through means that the bits have whipped through and disappeared. Actually, Cisco switches buffer frames regardless of switching mode. This means that the switch can calculate the CRC, as you say, and keep track of bad CRC counts. There's another important reason that it must buffer the frame. What if the output port is a shared (half-duplex) Ethernet? The router must obey CSMA/CD rules in that case and it may not be able to transmit the bits right away. The medium might be busy and the frame must be deferred. In that case, it's a good thing that the frame was buffered. Priscilla At 09:27 AM 8/17/01, Peter Van Oene wrote: >This means that although the switch cannot prevent the forwarding of invalid >frames since it begins forwarding prior to verifying the checksum, it can >keep track of the number of errored frames since it does eventually verify >the checksum. In other words, unlike store and forward switches who verify >the checksum before forwarding, by the time a cut-through switch realizes >the frame is bad, the damage is done. This is key for modes like >adaptive/dynamic cut-through or whatever marketing calls it these days, >where a switch can use cut-through until a specific error threshhold is >reached and then dynamically switch to store and forward mode. In practice >however, the latency variance between modes is so minimal that I believe >almost all switches use store and forward. > >Pete > > >*** REPLY SEPARATOR *** > >On 8/17/2001 at 6:39 AM Phil Barker wrote: > > >Just reading "Layer 2 Switching and Bridging" by Leigh > >Anne Chisholm. > > > >Cut-Through > > > >"Since the port does not wait to receive the CRC at > >the end 'if/of' the frame, it cannot determine the > >integrity of the data received" > > > >Happy with that. > > > >"Cut-through switches CAN perform a CRC check as the > >frame passes through the switch, keeping track of the > >number of bad frames the port receives". > > > >I'm Confused. > > > >I'm guessing that some form of CRC checksum can be > >calculated on the first X-bits of the frame before the > >cut-through process is allowed rather than the entire > >frame. > > > >Any ideas ? > > > >Phil. > > > > > > > > > >Do You Yahoo!? > >Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk > >or your free @yahoo.ie address at http://mail.yahoo.ie Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=16410&t=16354 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Certificationzone White Paper ? [7:16354]
Unlike a store-and-forward switch, a cut-through switch will not hold onto the frame while calculating the checksum. The frame will pass through the switch--bad or not. A CRC checksum cannot be calculated on the first X-bits of the frame. A checksum is performed to determine if that value agrees with the value contained in the frame received. Since the original CRC references the length of the frame, it would be impossible to compute a CRC checksum on a portion of the frame to determine its validity. Hope that helps explain things (but I think Howard and Peter did a good job already). -- Leigh Anne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Phil Barker Sent: Friday, August 17, 2001 4:40 AM To: [EMAIL PROTECTED] Subject: Certificationzone White Paper ? [7:16354] Just reading "Layer 2 Switching and Bridging" by Leigh Anne Chisholm. Cut-Through "Since the port does not wait to receive the CRC at the end 'if/of' the frame, it cannot determine the integrity of the data received" Happy with that. "Cut-through switches CAN perform a CRC check as the frame passes through the switch, keeping track of the number of bad frames the port receives". I'm Confused. I'm guessing that some form of CRC checksum can be calculated on the first X-bits of the frame before the cut-through process is allowed rather than the entire frame. Any ideas ? Phil. Do You Yahoo!? Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk or your free @yahoo.ie address at http://mail.yahoo.ie Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=16399&t=16354 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Certificationzone White Paper ? [7:16354]
This means that although the switch cannot prevent the forwarding of invalid frames since it begins forwarding prior to verifying the checksum, it can keep track of the number of errored frames since it does eventually verify the checksum. In other words, unlike store and forward switches who verify the checksum before forwarding, by the time a cut-through switch realizes the frame is bad, the damage is done. This is key for modes like adaptive/dynamic cut-through or whatever marketing calls it these days, where a switch can use cut-through until a specific error threshhold is reached and then dynamically switch to store and forward mode. In practice however, the latency variance between modes is so minimal that I believe almost all switches use store and forward. Pete *** REPLY SEPARATOR *** On 8/17/2001 at 6:39 AM Phil Barker wrote: >Just reading "Layer 2 Switching and Bridging" by Leigh >Anne Chisholm. > >Cut-Through > >"Since the port does not wait to receive the CRC at >the end 'if/of' the frame, it cannot determine the >integrity of the data received" > >Happy with that. > >"Cut-through switches CAN perform a CRC check as the >frame passes through the switch, keeping track of the >number of bad frames the port receives". > >I'm Confused. > >I'm guessing that some form of CRC checksum can be >calculated on the first X-bits of the frame before the >cut-through process is allowed rather than the entire >frame. > >Any ideas ? > >Phil. > > > > >Do You Yahoo!? >Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk >or your free @yahoo.ie address at http://mail.yahoo.ie Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=16364&t=16354 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Certificationzone White Paper ? [7:16354]
>Just reading "Layer 2 Switching and Bridging" by Leigh >Anne Chisholm. Leigh Anne can answer with exactly what she had in mind, but let me make some observations. > >Cut-Through > >"Since the port does not wait to receive the CRC at >the end 'if/of' the frame, it cannot determine the >integrity of the data received" > >Happy with that. Note this is per-frame. > >"Cut-through switches CAN perform a CRC check as the >frame passes through the switch, keeping track of the >number of bad frames the port receives". > >I'm Confused. No, a CRC can be calculated on a frame after it completely passes through the ingress port, but by then it's already cut through. But this doesn't limit the switch's ability to calculate the percentage of bad frames over a period of time. If this percentage exceeds a threshold, the port can switch to store-and-forward mode. > >I'm guessing that some form of CRC checksum can be >calculated on the first X-bits of the frame before the >cut-through process is allowed rather than the entire >frame. > >Any ideas ? > >Phil. > > > > >Do You Yahoo!? >Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk >or your free @yahoo.ie address at http://mail.yahoo.ie Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=16361&t=16354 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: CertificationZone White Paper EIGRP ?
Hi, I am pasting the feedback which I got it from one of the author for the same query -- My Question -- Check the formula for the composite metric - If k5 is 0, then the metric becomes 0 as per your formula. Instead of * k5, should it be + k5 ? Feed back --- Nope--it should be multiplied. EIGRP doesn't follow your normal everyday rules of algebra! :-) If k5 is 0, then this term of the formula (the multiply by k5) is ignored. It should probably be written: * max(k5, 1) or something like that. :-) Russ Regards / Thangavel HCL Technologies Ltd. Chennai --INDIA. - Original Message - From: "Chuck Larrieu" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Tuesday, January 16, 2001 10:19 AM Subject: RE: CertificationZone White Paper EIGRP ? > Formulae? > > You been going to night school again? :-> > > Chuck > > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of > [EMAIL PROTECTED] > Sent: Monday, January 15, 2001 2:04 PM > To: [EMAIL PROTECTED] > Subject: RE: CertificationZone White Paper EIGRP ? > > Phil, > Doyle (Routing TCP/IP, volume 1) has a slightly more useful explanation. > In the IGRP chapter (he doesn't dicuss EIGRP metrics much as he just refers > back to the IGRP formula which is the same), he explains "If k5 is set to > 0, the [k5/(reliability + k4)] term is not used". It implies that there > are essentially two different formulae: > [k1*BW + (k2 * BW)/(256-load) + k3 * delay] * [k5/(reliability + k4)] if k5 > <> 0, and > [k1*BW + (k2 * BW)/(256-load) + k3 * delay] if k5 = 0. > > I agree with you on the maths :-) > > JMcL > -- Forwarded by Jenny Mcleod/NSO/CSDA on 16/01/2001 > 08:52 am --- > > > Phil Barker <[EMAIL PROTECTED]>@groupstudy.com on 16/01/2001 > 04:46:09 am > > Please respond to Phil Barker <[EMAIL PROTECTED]> > > Sent by: [EMAIL PROTECTED] > > > > To: [EMAIL PROTECTED] > cisco GroupStudy <[EMAIL PROTECTED]> > cc: > > > Subject: RE: CertificationZone White Paper EIGRP ? > > > Thanks for that link Glen, > > It looks now like its me against the world. > > In the UK I would call K5 the nominator of this part > of the equation and "reliability + k4" would be the > denominator. > > If the nominator = 0 then the expression k5/(rel + k4) > will be 0. As a result when multiplying by anything on > the left will result in 0. > > I'm wondering if there is a difference in algebraic > notation batween USA and UK or if I need to go back to > school ? > > Regards, > > Phil. > > --- Glenn Johnson <[EMAIL PROTECTED]> wrote: > > http://www.cisco.com/warp/public/103/eigrp1.html > > > > -Original Message- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED]]On Behalf Of > > Phil Barker > > Sent: Monday, January 15, 2001 11:59 AM > > To: cisco GroupStudy > > Subject: CertificationZone White Paper EIGRP ? > > > > > > > > I'm having trouble with the equation referenced on > > page 5 (A4) concerning the metric calculation. > > Ref Don Dettmore. > > > > If this equation is correct as it stands and > > K2=K4=K5=0 > > Then the Right Side of the equation will be 0, which > > when multiplied by whatever on the left side will > > equal 0. i.e metric = 0. I'm guessing a little that > > these two sides should be added together not > > multiplied ? Can anyone verify this ? > > > > I've cross checked this with Ivan Pepelnjak' book on > > EIGRP. Chapter 1, Page 10 "Computing a Composite > > Metric" appears to verify that the White Paper is > > CORRECT. They both suggest that if K5 = 0 then the > > Composite Metric = 0 ??? > > > > Ivan also suggests that if all K-Values are set to > > zero then the composite metric is always 1 ? > > > > Wether or not you add or multiply both sides > > together > > the composite metric will = 0. > > > > Anyway, there is also a typo below 108 should read > > 10^8 > > > > > > > > >>SNIP > > This differs from the bandwidth usage in OSPF, in > > which route cost, by default, derives from the sum > > of > > interface costs along the path. OSPF interface cost > > defaults to 108/interfaceBandwidth, where > > interfaceBandwidth is 1544 or the value of the > > interface bandwidth commands (with a value in > > kilobits). > > > > > > >>END SNIP >
RE: CertificationZone White Paper EIGRP ?
Formulae? You been going to night school again? :-> Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of [EMAIL PROTECTED] Sent: Monday, January 15, 2001 2:04 PM To: [EMAIL PROTECTED] Subject: RE: CertificationZone White Paper EIGRP ? Phil, Doyle (Routing TCP/IP, volume 1) has a slightly more useful explanation. In the IGRP chapter (he doesn't dicuss EIGRP metrics much as he just refers back to the IGRP formula which is the same), he explains "If k5 is set to 0, the [k5/(reliability + k4)] term is not used". It implies that there are essentially two different formulae: [k1*BW + (k2 * BW)/(256-load) + k3 * delay] * [k5/(reliability + k4)] if k5 <> 0, and [k1*BW + (k2 * BW)/(256-load) + k3 * delay] if k5 = 0. I agree with you on the maths :-) JMcL -- Forwarded by Jenny Mcleod/NSO/CSDA on 16/01/2001 08:52 am --- Phil Barker <[EMAIL PROTECTED]>@groupstudy.com on 16/01/2001 04:46:09 am Please respond to Phil Barker <[EMAIL PROTECTED]> Sent by: [EMAIL PROTECTED] To: [EMAIL PROTECTED] cisco GroupStudy <[EMAIL PROTECTED]> cc: Subject: RE: CertificationZone White Paper EIGRP ? Thanks for that link Glen, It looks now like its me against the world. In the UK I would call K5 the nominator of this part of the equation and "reliability + k4" would be the denominator. If the nominator = 0 then the expression k5/(rel + k4) will be 0. As a result when multiplying by anything on the left will result in 0. I'm wondering if there is a difference in algebraic notation batween USA and UK or if I need to go back to school ? Regards, Phil. --- Glenn Johnson <[EMAIL PROTECTED]> wrote: > http://www.cisco.com/warp/public/103/eigrp1.html > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]]On Behalf Of > Phil Barker > Sent: Monday, January 15, 2001 11:59 AM > To: cisco GroupStudy > Subject: CertificationZone White Paper EIGRP ? > > > > I'm having trouble with the equation referenced on > page 5 (A4) concerning the metric calculation. > Ref Don Dettmore. > > If this equation is correct as it stands and > K2=K4=K5=0 > Then the Right Side of the equation will be 0, which > when multiplied by whatever on the left side will > equal 0. i.e metric = 0. I'm guessing a little that > these two sides should be added together not > multiplied ? Can anyone verify this ? > > I've cross checked this with Ivan Pepelnjak' book on > EIGRP. Chapter 1, Page 10 "Computing a Composite > Metric" appears to verify that the White Paper is > CORRECT. They both suggest that if K5 = 0 then the > Composite Metric = 0 ??? > > Ivan also suggests that if all K-Values are set to > zero then the composite metric is always 1 ? > > Wether or not you add or multiply both sides > together > the composite metric will = 0. > > Anyway, there is also a typo below 108 should read > 10^8 > > > > >>SNIP > This differs from the bandwidth usage in OSPF, in > which route cost, by default, derives from the sum > of > interface costs along the path. OSPF interface cost > defaults to 108/interfaceBandwidth, where > interfaceBandwidth is 1544 or the value of the > interface bandwidth commands (with a value in > kilobits). > > > >>END SNIP > > > Any thoughts ? > > Phil. > > > > Do You Yahoo!? > Get your free @yahoo.co.uk address at > http://mail.yahoo.co.uk > or your free @yahoo.ie address at > http://mail.yahoo.ie > > _ > FAQ, list archives, and subscription info: > http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to > [EMAIL PROTECTED] > Do You Yahoo!? Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk or your free @yahoo.ie address at http://mail.yahoo.ie _ 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] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: CertificationZone White Paper EIGRP ?
In the U.S., we can't do math. We learn "self esteem" in our schools, not that yucky math stuff. &;-) Actually, I wonder if Garcia-Luna-Aceves is from the U.S. It sounds like he might be from South America where the schools may be more rigorous. Priscilla At 09:03 AM 1/16/01, [EMAIL PROTECTED] wrote: >Phil, >Doyle (Routing TCP/IP, volume 1) has a slightly more useful explanation. >In the IGRP chapter (he doesn't dicuss EIGRP metrics much as he just refers >back to the IGRP formula which is the same), he explains "If k5 is set to >0, the [k5/(reliability + k4)] term is not used". It implies that there >are essentially two different formulae: >[k1*BW + (k2 * BW)/(256-load) + k3 * delay] * [k5/(reliability + k4)] if k5 ><> 0, and >[k1*BW + (k2 * BW)/(256-load) + k3 * delay] if k5 = 0. > >I agree with you on the maths :-) > >JMcL >-- Forwarded by Jenny Mcleod/NSO/CSDA on 16/01/2001 >08:52 am --- > > >Phil Barker <[EMAIL PROTECTED]>@groupstudy.com on 16/01/2001 >04:46:09 am > >Please respond to Phil Barker <[EMAIL PROTECTED]> > >Sent by: [EMAIL PROTECTED] > > > >To: [EMAIL PROTECTED] > cisco GroupStudy <[EMAIL PROTECTED]> >cc: > > >Subject: RE: CertificationZone White Paper EIGRP ? > > >Thanks for that link Glen, > >It looks now like its me against the world. > >In the UK I would call K5 the nominator of this part >of the equation and "reliability + k4" would be the >denominator. > >If the nominator = 0 then the expression k5/(rel + k4) >will be 0. As a result when multiplying by anything on >the left will result in 0. > >I'm wondering if there is a difference in algebraic >notation batween USA and UK or if I need to go back to >school ? > >Regards, > >Phil. > >--- Glenn Johnson <[EMAIL PROTECTED]> wrote: > >http://www.cisco.com/warp/public/103/eigrp1.html > > > > -Original Message- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED]]On Behalf Of > > Phil Barker > > Sent: Monday, January 15, 2001 11:59 AM > > To: cisco GroupStudy > > Subject: CertificationZone White Paper EIGRP ? > > > > > > > > I'm having trouble with the equation referenced on > > page 5 (A4) concerning the metric calculation. > > Ref Don Dettmore. > > > > If this equation is correct as it stands and > > K2=K4=K5=0 > > Then the Right Side of the equation will be 0, which > > when multiplied by whatever on the left side will > > equal 0. i.e metric = 0. I'm guessing a little that > > these two sides should be added together not > > multiplied ? Can anyone verify this ? > > > > I've cross checked this with Ivan Pepelnjak' book on > > EIGRP. Chapter 1, Page 10 "Computing a Composite > > Metric" appears to verify that the White Paper is > > CORRECT. They both suggest that if K5 = 0 then the > > Composite Metric = 0 ??? > > > > Ivan also suggests that if all K-Values are set to > > zero then the composite metric is always 1 ? > > > > Wether or not you add or multiply both sides > > together > > the composite metric will = 0. > > > > Anyway, there is also a typo below 108 should read > > 10^8 > > > > > > > > >>SNIP > > This differs from the bandwidth usage in OSPF, in > > which route cost, by default, derives from the sum > > of > > interface costs along the path. OSPF interface cost > > defaults to 108/interfaceBandwidth, where > > interfaceBandwidth is 1544 or the value of the > > interface bandwidth commands (with a value in > > kilobits). > > > > > > >>END SNIP > > > > > > Any thoughts ? > > > > Phil. > > > > > > > > > Do You Yahoo!? > > Get your free @yahoo.co.uk address at > > http://mail.yahoo.co.uk > > or your free @yahoo.ie address at > > http://mail.yahoo.ie > > > > _ > > FAQ, list archives, and subscription info: > > http://www.groupstudy.com/list/cisco.html > > Report misconduct and Nondisclosure violations to > > [EMAIL PROTECTED] > > > > > >Do You Yahoo!? >Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk >or your free @yahoo.ie address at http://mail.yahoo.ie > >_ >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] Priscilla Oppenheimer http://www.priscilla.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: CertificationZone White Paper EIGRP ?
Phil, Doyle (Routing TCP/IP, volume 1) has a slightly more useful explanation. In the IGRP chapter (he doesn't dicuss EIGRP metrics much as he just refers back to the IGRP formula which is the same), he explains "If k5 is set to 0, the [k5/(reliability + k4)] term is not used". It implies that there are essentially two different formulae: [k1*BW + (k2 * BW)/(256-load) + k3 * delay] * [k5/(reliability + k4)] if k5 <> 0, and [k1*BW + (k2 * BW)/(256-load) + k3 * delay] if k5 = 0. I agree with you on the maths :-) JMcL -- Forwarded by Jenny Mcleod/NSO/CSDA on 16/01/2001 08:52 am --- Phil Barker <[EMAIL PROTECTED]>@groupstudy.com on 16/01/2001 04:46:09 am Please respond to Phil Barker <[EMAIL PROTECTED]> Sent by: [EMAIL PROTECTED] To: [EMAIL PROTECTED] cisco GroupStudy <[EMAIL PROTECTED]> cc: Subject: RE: CertificationZone White Paper EIGRP ? Thanks for that link Glen, It looks now like its me against the world. In the UK I would call K5 the nominator of this part of the equation and "reliability + k4" would be the denominator. If the nominator = 0 then the expression k5/(rel + k4) will be 0. As a result when multiplying by anything on the left will result in 0. I'm wondering if there is a difference in algebraic notation batween USA and UK or if I need to go back to school ? Regards, Phil. --- Glenn Johnson <[EMAIL PROTECTED]> wrote: > http://www.cisco.com/warp/public/103/eigrp1.html > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]]On Behalf Of > Phil Barker > Sent: Monday, January 15, 2001 11:59 AM > To: cisco GroupStudy > Subject: CertificationZone White Paper EIGRP ? > > > > I'm having trouble with the equation referenced on > page 5 (A4) concerning the metric calculation. > Ref Don Dettmore. > > If this equation is correct as it stands and > K2=K4=K5=0 > Then the Right Side of the equation will be 0, which > when multiplied by whatever on the left side will > equal 0. i.e metric = 0. I'm guessing a little that > these two sides should be added together not > multiplied ? Can anyone verify this ? > > I've cross checked this with Ivan Pepelnjak' book on > EIGRP. Chapter 1, Page 10 "Computing a Composite > Metric" appears to verify that the White Paper is > CORRECT. They both suggest that if K5 = 0 then the > Composite Metric = 0 ??? > > Ivan also suggests that if all K-Values are set to > zero then the composite metric is always 1 ? > > Wether or not you add or multiply both sides > together > the composite metric will = 0. > > Anyway, there is also a typo below 108 should read > 10^8 > > > > >>SNIP > This differs from the bandwidth usage in OSPF, in > which route cost, by default, derives from the sum > of > interface costs along the path. OSPF interface cost > defaults to 108/interfaceBandwidth, where > interfaceBandwidth is 1544 or the value of the > interface bandwidth commands (with a value in > kilobits). > > > >>END SNIP > > > Any thoughts ? > > Phil. > > > > Do You Yahoo!? > Get your free @yahoo.co.uk address at > http://mail.yahoo.co.uk > or your free @yahoo.ie address at > http://mail.yahoo.ie > > _ > FAQ, list archives, and subscription info: > http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to > [EMAIL PROTECTED] > Do You Yahoo!? Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk or your free @yahoo.ie address at http://mail.yahoo.ie _ 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]
RE: CertificationZone White Paper EIGRP ?
No, no need to go back to school. Cisco takes liberties with the rules of algebra for purposes of the EIGRP/IGRP metric calculation. If K5=0, the last term is ignored. This is covered in BSCN, and in the book, "EIGRP for IP" by Retana, Slice & White. Pamela On Mon, 15 Jan 2001, [iso-8859-1] Phil Barker wrote: > Thanks for that link Glen, > > It looks now like its me against the world. > > In the UK I would call K5 the nominator of this part > of the equation and "reliability + k4" would be the > denominator. > > If the nominator = 0 then the expression k5/(rel + k4) > will be 0. As a result when multiplying by anything on > the left will result in 0. > > I'm wondering if there is a difference in algebraic > notation batween USA and UK or if I need to go back to > school ? > > Regards, > > Phil. > > --- Glenn Johnson <[EMAIL PROTECTED]> wrote: > > http://www.cisco.com/warp/public/103/eigrp1.html > > > > -Original Message- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED]]On Behalf Of > > Phil Barker > > Sent: Monday, January 15, 2001 11:59 AM > > To: cisco GroupStudy > > Subject: CertificationZone White Paper EIGRP ? > > > > > > > > I'm having trouble with the equation referenced on > > page 5 (A4) concerning the metric calculation. > > Ref Don Dettmore. > > > > If this equation is correct as it stands and > > K2=K4=K5=0 > > Then the Right Side of the equation will be 0, which > > when multiplied by whatever on the left side will > > equal 0. i.e metric = 0. I'm guessing a little that > > these two sides should be added together not > > multiplied ? Can anyone verify this ? > > > > I've cross checked this with Ivan Pepelnjak' book on > > EIGRP. Chapter 1, Page 10 "Computing a Composite > > Metric" appears to verify that the White Paper is > > CORRECT. They both suggest that if K5 = 0 then the > > Composite Metric = 0 ??? > > > > Ivan also suggests that if all K-Values are set to > > zero then the composite metric is always 1 ? > > > > Wether or not you add or multiply both sides > > together > > the composite metric will = 0. > > > > Anyway, there is also a typo below 108 should read > > 10^8 > > > > > > > > >>SNIP > > This differs from the bandwidth usage in OSPF, in > > which route cost, by default, derives from the sum > > of > > interface costs along the path. OSPF interface cost > > defaults to 108/interfaceBandwidth, where > > interfaceBandwidth is 1544 or the value of the > > interface bandwidth commands (with a value in > > kilobits). > > > > > > >>END SNIP > > > > > > Any thoughts ? > > > > Phil. > > > > > > > > > Do You Yahoo!? > > Get your free @yahoo.co.uk address at > > http://mail.yahoo.co.uk > > or your free @yahoo.ie address at > > http://mail.yahoo.ie > > > > _ > > FAQ, list archives, and subscription info: > > http://www.groupstudy.com/list/cisco.html > > Report misconduct and Nondisclosure violations to > > [EMAIL PROTECTED] > > > > > > Do You Yahoo!? > Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk > or your free @yahoo.ie address at http://mail.yahoo.ie > > _ > 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]
RE: CertificationZone White Paper EIGRP ?
Thanks for that link Glen, It looks now like its me against the world. In the UK I would call K5 the nominator of this part of the equation and "reliability + k4" would be the denominator. If the nominator = 0 then the expression k5/(rel + k4) will be 0. As a result when multiplying by anything on the left will result in 0. I'm wondering if there is a difference in algebraic notation batween USA and UK or if I need to go back to school ? Regards, Phil. --- Glenn Johnson <[EMAIL PROTECTED]> wrote: > http://www.cisco.com/warp/public/103/eigrp1.html > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]]On Behalf Of > Phil Barker > Sent: Monday, January 15, 2001 11:59 AM > To: cisco GroupStudy > Subject: CertificationZone White Paper EIGRP ? > > > > I'm having trouble with the equation referenced on > page 5 (A4) concerning the metric calculation. > Ref Don Dettmore. > > If this equation is correct as it stands and > K2=K4=K5=0 > Then the Right Side of the equation will be 0, which > when multiplied by whatever on the left side will > equal 0. i.e metric = 0. I'm guessing a little that > these two sides should be added together not > multiplied ? Can anyone verify this ? > > I've cross checked this with Ivan Pepelnjak' book on > EIGRP. Chapter 1, Page 10 "Computing a Composite > Metric" appears to verify that the White Paper is > CORRECT. They both suggest that if K5 = 0 then the > Composite Metric = 0 ??? > > Ivan also suggests that if all K-Values are set to > zero then the composite metric is always 1 ? > > Wether or not you add or multiply both sides > together > the composite metric will = 0. > > Anyway, there is also a typo below 108 should read > 10^8 > > > > >>SNIP > This differs from the bandwidth usage in OSPF, in > which route cost, by default, derives from the sum > of > interface costs along the path. OSPF interface cost > defaults to 108/interfaceBandwidth, where > interfaceBandwidth is 1544 or the value of the > interface bandwidth commands (with a value in > kilobits). > > > >>END SNIP > > > Any thoughts ? > > Phil. > > > > Do You Yahoo!? > Get your free @yahoo.co.uk address at > http://mail.yahoo.co.uk > or your free @yahoo.ie address at > http://mail.yahoo.ie > > _ > FAQ, list archives, and subscription info: > http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to > [EMAIL PROTECTED] > Do You Yahoo!? Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk or your free @yahoo.ie address at http://mail.yahoo.ie _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: CertificationZone White Paper EIGRP ?
Think of it this way The only K values that are set to 1 are K1 and K3 which are Bandwidth and Delay. If all other values are set to 0, then the metric calculation in Eigrp will be dependent on the values of Bandwidth and Delay which is a truth in Eigrp world. To cut a long story short. K2=K4=K5=0 means that by default, these values are 0. --- Phil Barker <[EMAIL PROTECTED]> wrote: > > I'm having trouble with the equation referenced on > page 5 (A4) concerning the metric calculation. > Ref Don Dettmore. > > If this equation is correct as it stands and > K2=K4=K5=0 > Then the Right Side of the equation will be 0, which > when multiplied by whatever on the left side will > equal 0. i.e metric = 0. I'm guessing a little that > these two sides should be added together not > multiplied ? Can anyone verify this ? > > I've cross checked this with Ivan Pepelnjak' book on > EIGRP. Chapter 1, Page 10 "Computing a Composite > Metric" appears to verify that the White Paper is > CORRECT. They both suggest that if K5 = 0 then the > Composite Metric = 0 ??? > > Ivan also suggests that if all K-Values are set to > zero then the composite metric is always 1 ? > > Wether or not you add or multiply both sides > together > the composite metric will = 0. > > Anyway, there is also a typo below 108 should read > 10^8 > > > > >>SNIP > This differs from the bandwidth usage in OSPF, in > which route cost, by default, derives from the sum > of > interface costs along the path. OSPF interface cost > defaults to 108/interfaceBandwidth, where > interfaceBandwidth is 1544 or the value of the > interface bandwidth commands (with a value in > kilobits). > > > >>END SNIP > > > Any thoughts ? > > Phil. > > > > Do You Yahoo!? > Get your free @yahoo.co.uk address at > http://mail.yahoo.co.uk > or your free @yahoo.ie address at > http://mail.yahoo.ie > > _ > FAQ, list archives, and subscription info: > http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] __ Do You Yahoo!? Get email at your own domain with Yahoo! Mail. http://personal.mail.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: CertificationZone White Paper EIGRP ?
http://www.cisco.com/warp/public/103/eigrp1.html -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Phil Barker Sent: Monday, January 15, 2001 11:59 AM To: cisco GroupStudy Subject: CertificationZone White Paper EIGRP ? I'm having trouble with the equation referenced on page 5 (A4) concerning the metric calculation. Ref Don Dettmore. If this equation is correct as it stands and K2=K4=K5=0 Then the Right Side of the equation will be 0, which when multiplied by whatever on the left side will equal 0. i.e metric = 0. I'm guessing a little that these two sides should be added together not multiplied ? Can anyone verify this ? I've cross checked this with Ivan Pepelnjak' book on EIGRP. Chapter 1, Page 10 "Computing a Composite Metric" appears to verify that the White Paper is CORRECT. They both suggest that if K5 = 0 then the Composite Metric = 0 ??? Ivan also suggests that if all K-Values are set to zero then the composite metric is always 1 ? Wether or not you add or multiply both sides together the composite metric will = 0. Anyway, there is also a typo below 108 should read 10^8 >>SNIP This differs from the bandwidth usage in OSPF, in which route cost, by default, derives from the sum of interface costs along the path. OSPF interface cost defaults to 108/interfaceBandwidth, where interfaceBandwidth is 1544 or the value of the interface bandwidth commands (with a value in kilobits). >>END SNIP Any thoughts ? Phil. Do You Yahoo!? Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk or your free @yahoo.ie address at http://mail.yahoo.ie _ 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]
RE: CertificationZone White Paper (Frame Relay) ???
I don't think any of my posts or replies are going through. ( stop laughing, you guys! ) The white paper is definitely in error. The frame relay header is 2 BYTES, 16 BITS in length. I reported the error to certification zone when I spotted it. So far they have not corrected it. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Phil Barker Sent: Monday, June 12, 2000 7:19 AM To: cisco GroupStudy Subject:CertificationZone White Paper (Frame Relay) ??? Hi, I don't think my last post got through so I'm sending again. My previous Question relates to page 3 of this paper by David Wolsefer. Under the heading of framing formats he refers to an 8 byte flags field and a 16 byte address field. I'm pretty certain this should be bits but don't have any reference material with me currently. 16 bytes seems rather excessive for a serial connection anyway. And a 16 byte FCS ??? Can anyone confirm ? PS: Is the author trying to scare me? "Before we get into the heart of frame relay, lets take a look at the framing formats" After reading the section on the address field I am scared. But seriously, I think this section needs a better diagram with all the relevant info detailed. Cheers, Phil. Do You Yahoo!? Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk or your free @yahoo.ie address at http://mail.yahoo.ie ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: CertificationZone White Paper (Frame Relay) ???
Hi Phil, It should be bits instead of bytes!! Rgds, Ramesh CCNA Phil Barker <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hi, > I don't think my last post got through so I'm > sending again. > > My previous Question relates to page 3 of this paper > by David Wolsefer. > Under the heading of framing formats he refers to an > 8 byte flags field and a 16 byte address field. I'm > pretty certain this should be bits but don't have any > reference material with me currently. 16 bytes seems > rather excessive for a serial connection anyway. > And a 16 byte FCS ??? > > Can anyone confirm ? > > PS: Is the author trying to scare me? > > "Before we get into the heart of frame relay, lets > take a look at the framing formats" > > After reading the section on the address field I am > scared. But seriously, I think this section needs a > better diagram with all the relevant info detailed. > > Cheers, > > Phil. > > > > > Do You Yahoo!? > Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk > or your free @yahoo.ie address at http://mail.yahoo.ie > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > --- ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: CertificationZone White Paper (Frame Relay) ???
this is most definitely an error. the correct term is BIT. I reported this to the folks at certification zone at the time I saw it. I guess no one corrected it. The frame relay header is 2 bytes - 16 bits. HTH Chuck Phil Barker <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hi, > I don't think my last post got through so I'm > sending again. > > My previous Question relates to page 3 of this paper > by David Wolsefer. > Under the heading of framing formats he refers to an > 8 byte flags field and a 16 byte address field. I'm > pretty certain this should be bits but don't have any > reference material with me currently. 16 bytes seems > rather excessive for a serial connection anyway. > And a 16 byte FCS ??? > > Can anyone confirm ? > > PS: Is the author trying to scare me? > > "Before we get into the heart of frame relay, lets > take a look at the framing formats" > > After reading the section on the address field I am > scared. But seriously, I think this section needs a > better diagram with all the relevant info detailed. > > Cheers, > > Phil. > > > > > Do You Yahoo!? > Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk > or your free @yahoo.ie address at http://mail.yahoo.ie > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > --- ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Certificationzone White Paper
Did you get the whitepaper? I have a copy... Nathan Eugene Chandler wrote: > Hello all, > > Does any have the white paper entitled > "CCIE Bridging", that appeared in the > January 2000 Certificationzone? > > If so, may I get you to email me a copy. > > Thank you very much. > > Eugene C. > [EMAIL PROTECTED] > > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > --- ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]