Garth,
If you are using BW and Delay in your calculation attempt then you should go
thru the blog I shared.
Regards,
Tyson Scott - CCIE #13513 R&S, Security, and SP
Managing Partner / Sr. Instructor - IPexpert, Inc.
Mailto: <mailto:tscott_at_ipexpert.com> tscott_at_ipexpert.com
From: Garth Bryden [mailto:hacked.the.planet.on.28.8k.dialup_at_gmail.com]
Sent: Tuesday, September 28, 2010 9:14 PM
To: Tyson Scott
Cc: Bilal Hansrod; Paul Negron; Cisco certification
Subject: Re: EIGRP Traffic Share Count
Hi Tyson,
Thanks heaps for your assistance!
Does this just apply when the metric is being calculated by delay only?
On Tue, Sep 28, 2010 at 12:03 PM, Tyson Scott <tscott_at_ipexpert.com> wrote:
Bilal,
I am glad it was helpful. Anything that we can do to unlock the mysteries
is what we like to do. That is why we are all on here helping you guys out.
Regards,
Tyson Scott - CCIE #13513 R&S, Security, and SP
Managing Partner / Sr. Instructor - IPexpert, Inc.
Mailto: tscott_at_ipexpert.com
From: Bilal Hansrod [mailto:bilal.hansrod_at_gmail.com]
Sent: Monday, September 27, 2010 10:29 PM
To: Tyson Scott
Cc: Paul Negron; Garth Bryden; Cisco certification
Subject: Re: EIGRP Traffic Share Count
Thank you Tyson - That was right on money, the below explanation has
releived lot of uneasy feeling from mind and heart in relation to EIGRP :)
Thanks once again and I will be reading these two blogs over and over to
understand EIGRP mystery.
Great blogs from ipexpert on EIGRP technology.
http://blog.ipexpert.com/2010/05/03/eigrp-unequal-cost-load-balancing/
http://blog.ipexpert.com/2010/03/03/eigrp-metric-k-values/
Regards,
Bilal
On Tue, Sep 28, 2010 at 1:57 AM, Tyson Scott <tscott_at_ipexpert.com> wrote:
Corrected Typos
Well metric isn't used as you have chosen to ignore BW.
With the following output
Rack1R6#show ip route 155.1.9.9
Routing entry for 155.1.9.0/24
Known via "eigrp 100", distance 90, metric 3072, type internal
Redistributing via eigrp 10, eigrp 100
Advertised by eigrp 10
Last update from 155.1.146.1 on FastEthernet0/0.146, 00:01:04 ago
Routing Descriptor Blocks:
155.1.146.1, from 155.1.146.1, 00:01:04 ago, via FastEthernet0/0.146
Route metric is 3584, traffic share count is 103
Total delay is 140 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 4
* 155.1.67.7, from 155.1.67.7, 00:01:04 ago, via FastEthernet0/0.67
Route metric is 3072, traffic share count is 120
Total delay is 120 microseconds, minimum bandwidth is 100000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
We can see the metric is greater on the first entry (3584) versus 3072 but
the route via Fa0/0.67 has a higher traffic share count that proves metric
isn't used. Here we are simply looking at delay (120 & 140). So 120 is our
traffic share base value to start with.
For the second value we will use 120 as the base number and times that by
the percentage of difference
120/140*120 = 102.857...
There is no easy way to simplify 120 and 103. 103 is a prime number so we
cannot simplify it. So our traffic share count is 120 and 103
For your last output of 160 usec/120 usec. Again 120 is our primary traffic
share count because it is the lowest delay which is the best metric.
For the second value we have 120/160*120 = 90. Now 120 and 90 can be
simplified by dividing each by 30 which gives you the traffic share count of
4 and 3.
Regards,
Tyson Scott - CCIE #13513 R&S, Security, and SP
Managing Partner / Sr. Instructor - IPexpert, Inc.
Mailto: tscott_at_ipexpert.com
From: Bilal Hansrod [mailto:bilal.hansrod_at_gmail.com]
Sent: Monday, September 27, 2010 10:40 AM
To: Tyson Scott
Cc: Paul Negron; Garth Bryden; Cisco certification
Subject: Re: EIGRP Traffic Share Count
Hi Tyson,
Actually, the numbers I gave you was from workbook. The below show output is
from live routers and only K3 enabled.
R6 - R1 = 100 usec
R1 - R3 = 20 usec
R3 - SW1 = 20 usec
SW1 - SW3 = 10 usec
SW3 - VLAN9 (155.1.9.9) = 10 usec
Total 160usec, which is showed in route via
155.1.146.1 (R1)
R6 - SW1 = 100 usec
SW1 - SW3 = 10 usec
SW3 - VLAN9 (155.1.9.9) = 10 usec
Total 120 usec, which is showed in route
via 155.1.67.7 (SW1)
So the question is how is share count 3 and 4 derived
Rack1R6#show ip route 155.1.9.9
Routing entry for 155.1.9.0/24
Known via "eigrp 100", distance 90, metric 3072, type internal
Redistributing via eigrp 100
Last update from 155.1.146.1 on FastEthernet0/0.146, 00:03:33 ago
Routing Descriptor Blocks:
155.1.146.1, from 155.1.146.1, 00:03:33 ago, via FastEthernet0/0.146
Route metric is 4096, traffic share count is 3
Total delay is 160 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 4
* 155.1.67.7, from 155.1.67.7, 00:03:33 ago, via FastEthernet0/0.67
Route metric is 3072, traffic share count is 4
Total delay is 120 microseconds, minimum bandwidth is 100000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
Rack1R6#show ip eigrp topology 155.1.9.0 255.255.255.0
IP-EIGRP (AS 100): Topology entry for 155.1.9.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 3072
Routing Descriptor Blocks:
155.1.67.7 (FastEthernet0/0.67), from 155.1.67.7, Send flag is 0x0
Composite metric is (3072/512), Route is Internal
Vector metric:
Minimum bandwidth is 100000 Kbit
Total delay is 120 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 2
155.1.146.1 (FastEthernet0/0.146), from 155.1.146.1, Send flag is 0x0
Composite metric is (4096/1536), Route is Internal
Vector metric:
Minimum bandwidth is 1544 Kbit
Total delay is 160 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 4
Rack1R6#
Thank you Tyson for taking your time and helping us on this concept.
Regards,
Bilal
On Tue, Sep 28, 2010 at 12:15 AM, Tyson Scott <tscott_at_ipexpert.com> wrote:
I mean "show ip eigrp topology 155.1.9.9
Regards,
Tyson Scott - CCIE #13513 R&S, Security, and SP
Managing Partner / Sr. Instructor - IPexpert, Inc.
Mailto: tscott_at_ipexpert.com
From: Bilal Hansrod [mailto:bilal.hansrod_at_gmail.com]
Sent: Monday, September 27, 2010 10:00 AM
To: Tyson Scott
Cc: Paul Negron; Garth Bryden; Cisco certification
Subject: Re: EIGRP Traffic Share Count
Thanks Tyson, I was reading your article since morning and it does make
sense if you want to take Bandwidth and Delay into account. I was only
taking delay into consideration while calculating the traffic share count.
Now, I know how to change the ratio , but still unable to understand the
default traffic ratio with below snippet.
Rack1R6#show ip route 155.1.9.9
Routing entry for 155.1.9.0/24
Known via "eigrp 100", distance 90, metric 3072, type internal
Redistributing via eigrp 10, eigrp 100
Advertised by eigrp 10
Last update from 155.1.146.1 on FastEthernet0/0.146, 00:01:04 ago
Routing Descriptor Blocks:
155.1.146.1, from 155.1.146.1, 00:01:04 ago, via FastEthernet0/0.146
Route metric is 3584, traffic share count is 103
Total delay is 140 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 4
* 155.1.67.7, from 155.1.67.7, 00:01:04 ago, via FastEthernet0/0.67
Route metric is 3072, traffic share count is 120
Total delay is 120 microseconds, minimum bandwidth is 100000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
How come above show ip route show traffic share of 103 and 120 respectively?
I have K3=1 and remaining K's are 0, meaning delay will be factored in. Any
suggestion as how these numbers is calculated before we change the traffic
share ratio.
Thanks,
Bilal
On Mon, Sep 27, 2010 at 11:51 PM, Tyson Scott <tscott_at_ipexpert.com> wrote:
You can change EIGRP to only take into account bandwidth if you change your
K values on the routers to ignore delay.
K1 = 1 K2-5 = 0
Without doing this you need to account for delay.
I already posted the article to our blog that will tell you how to calculate
traffic share values and the formula for calculation.
Regards,
Tyson Scott - CCIE #13513 R&S, Security, and SP
Managing Partner / Sr. Instructor - IPexpert, Inc.
Mailto: tscott_at_ipexpert.com
-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
Bilal Hansrod
Sent: Monday, September 27, 2010 1:52 AM
To: Paul Negron
Cc: Garth Bryden; Cisco certification
Subject: Re: EIGRP Traffic Share Count
Thanks Paul, atleast it cleared few doubts. Anyways, it might be a stupid
question, but how did you manage to arrive at metrics with only bandwidth
value. I tried to plugged in bandwidth value of 100 , but unable to get the
metric of 6530560.
Can you please shed some light on metric calculation.
EIGRP Metric = 256*((10^7 / min. Bw) + Delay)
Regards,
Bilal
On Mon, Sep 27, 2010 at 3:42 PM, Paul Negron <negron.paul_at_gmail.com> wrote:
> I'm still trying to figure that one out too. I'm afraid I will run into
the
> dreaded Cisco EIGRP SECRET wall. When I know you'll know. Unless someone
> steps up and fills in the blank.
>
> It really doesn't seem to matter though except for the number of packets
> being sent per link. The load sharing is very consistent.
> --
> Paul Negron
> CCIE# 14856 CCSI# 22752
> Senior Technical Instructor
> www.micronicstraining.com <http://www.micronicstraining.com/>
>
>
>
> > From: Garth Bryden <hacked.the.planet.on.28.8k.dialup_at_gmail.com>
> > Date: Mon, 27 Sep 2010 12:13:24 +0800
> > To: Paul Negron <negron.paul_at_gmail.com>
> > Cc: Bilal Hansrod <bilal.hansrod_at_gmail.com>, Cisco certification
> > <ccielab_at_groupstudy.com>
> > Subject: Re: EIGRP Traffic Share Count
> >
> > Hi Paul,
> >
> > Thanks I am still a little confused about how we managed to get the
value
> of
> > 61 from the metrics?
> >
> > Sent from my iPad
> >
> > On 27/09/2010, at 11:02 AM, Paul Negron <negron.paul_at_gmail.com> wrote:
> >
> >> Fellas,
> >>
> >> First of all. Make sure you change the delay for the interface to be 10
> if
> >> you are using dynamips. Yes, it is off.
> >>
> >> If you were to take 4 paths with the following bandwidths:
> >>
> >> 1 = 100K
> >> 2 = 200K
> >> 3 = 300K
> >> 4 = 400K (This being the best path)
> >>
> >> After configuring a variance of 4:
> >>
> >> The following metrics would be used:
> >>
> >> 1 = 6530560 traffic-count = 240
> >> 2 = 8663808 traffic-count = 181
> >> 3 = 12930560 traffic-count = 121
> >> 4 = 25730560 traffic-count = 61
> >>
> >>
> >> What Garth said takes over from here:
> >>
> >> Largest metric (25730560) divided by path 1 metric (6530560) =
> 3.94002352
> >> Therefore the traffic-share of path 4 (61) * 3.94002352 = 240.341
> >> rounded down to the nearest integer is 240.
> >>
> >> Largest metric (25730560) / path 2 metric (8663808) = 2.969890376
> >> Therefore the traffic-share of path 4 (61) * 2.969890376 = 181.16
> >> rounded down to the nearest integer is 181.
> >>
> >> Largest metric (25730560) / path 3 metric (12930560) = 2.969890376
> >> Therefore the traffic-share of path 4 (61) * 1.98990299 = 121.38
> rounded
> >> down to the nearest integer is 121.
> >>
> >> Largest metric (25730560) / path 4 metric (25730560) = 1
> >> Therefore the traffic-share of path 4 (61) * 1 = 61 rounded down to
> the
> >> nearest integer is 61.
> >>
> >> Sure enough, I tested this by turning off CEF and I observed 240
packets
> >> down PATH 4 , 121 packets down path 3 and so fourth.
> >>
> >> This is how it works Gentlemen.
> >>
> >> Paul
> >> --
> >> Paul Negron
> >> CCIE# 14856 CCSI# 22752
> >> Senior Technical Instructor
> >> www.micronicstraining.com <http://www.micronicstraining.com/>
> >>
> >>
> >>
> >>> From: Bilal Hansrod <bilal.hansrod_at_gmail.com>
> >>> Reply-To: Bilal Hansrod <bilal.hansrod_at_gmail.com>
> >>> Date: Mon, 27 Sep 2010 11:22:22 +1000
> >>> To: Garth Bryden <hacked.the.planet.on.28.8k.dialup_at_gmail.com>
> >>> Cc: Cisco certification <ccielab_at_groupstudy.com>
> >>> Subject: Re: EIGRP Traffic Share Count
> >>>
> >>> Sorry Garth, I didn't mean to confuse you, but waiting for big boys to
> come
> >>> up with logical explanation when they have time :-)
> >>>
> >>> Regards,
> >>>
> >>> Bilal H
> >>>
> >>>
> >>>
> >>>
> >>> On Mon, Sep 27, 2010 at 11:12 AM, Garth Bryden <
> >>> hacked.the.planet.on.28.8k.dialup_at_gmail.com> wrote:
> >>>
> >>>> Would be nice to find out why such the large values, I believe it is
> so it
> >>>> can get the share ratio as accurate as possible while using whole
> numbers,
> >>>> because the actual ratio is so close.
> >>>>
> >>>> Though, I always believed the traffic share count would always start
> at 1
> >>>> then the rest of the paths increased based on the ratio.. if the
> numbers
> >>>> where not whole numbers then it'd be rounded down to the whole
> number.. but
> >>>> based on that logic your traffic share count 1:1 not 103:120
> >>>>
> >>>> Though after googling to try find some information on it, I've come
> back
> >>>> with nothing and more confused than before!! There is a cisco press
> book
> >>>> "Traffic Engineering with MPLS" which is saying non-whole numbers are
> >>>> rounded UP to the nearest integer not rounded DOWN though all the
> Cisco
> >>>> Documentation says it is rounded down. :-/
> >>>>
> >>>> On Mon, Sep 27, 2010 at 8:44 AM, Bilal Hansrod
> >>> <bilal.hansrod_at_gmail.com>wrote:
> >>>>
> >>>>> Hello again,
> >>>>>
> >>>>> Garth has provided a valuable resource to calculate Traffic Share
and
> >>>>> detail about load sharing. Can anyone else, please provide more
> >>>>> understanding on how to calculate share based on examples as I am
> having
> >>>>> difficulty understanding nuts and bolts of Traffic Share Count.
> >>>>>
> >>>>> Thanks everyone -
> >>>>>
> >>>>> Regards,
> >>>>> Bilal
> >>>>>
> >>>>> On Sun, Sep 26, 2010 at 11:42 PM, Bilal Hansrod <
> >>>>> bilal.hansrod_at_gmail.com> wrote:
> >>>>>
> >>>>>> Thanks Garth, but still I am trying to understand Traffic Share
> Count
> >>>>>> value arrived via calculation. How did you get 120 via 155.1.67.7
> and 103
> >>>>>> via 155.1.146.1 (please see below output from show ip route
> 155.1.9.9).
> >>>>>> There is a lab in INE W1 and it asks to change the traffic share to
> 1:5
> >>> and
> >>>>>> uses the formula:
> >>>>>>
> >>>>>> INE Task 5.15 EIGRP Unequal Cost Load Balancing
> >>>>>>
> >>>>>> "These paths are now balanced 103:120. To achieve the desired 1:5
> traffic
> >>>>>> share,
> >>>>>> R6 s delay on the link to R1 must be updated. The actual values
used
> on
> >>>>>> R1,
> >>>>>> R3, and R6 for delay can have multiple valid options as long as two
> >>>>>> conditions
> >>>>>> are true. First, the Advertised Distance R1 sends to R6 must be
> lower
> >>>>>> than R6 s
> >>>>>> Feasible Distance. Secondly the entire composite result R6
> calculates
> >>>>>> through
> >>>>>> R1 should be five times the Feasible Distance.
> >>>>>> In our case R1 s Advertised Distance is 40 microseconds, or 4 tens
> of
> >>>>>> microseconds. This specifically means the following must be true if
> we
> >>>>>> want a
> >>>>>> traffic share of 1:5.
> >>>>>> 3072 * 5 = (R6_TO_R1_DLY + 4) * 256
> >>>>>> Therefore R6 s delay to R1 should be 56 tens of microseconds."
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> On Sun, Sep 26, 2010 at 10:29 PM, Garth Bryden <
> >>>>>> hacked.the.planet.on.28.8k.dialup_at_gmail.com> wrote:
> >>>>>>
> >>>>>>> Hi Bilal,
> >>>>>>>
> >>>>>>> You want to read this post-
> >>>>>>>
> >>>
> http://blog.ine.com/2009/05/01/understanding-unequal-cost-load-balancing/
> ..
> >>>>>>> This has an explanation on the traffic share ratio you are seeing
> above.
> >>>>>>>
> >>>>>>> I think the answer you seek though is
> >>>>>>>
> >>>>>>> EIGRP will divide each links metric by the largest paths metric..
> >>>>>>>
> >>>>>>> 3584 / 3072 which is 1.166
> >>>>>>> 3584 / 3584 which is 1
> >>>>>>>
> >>>>>>> FYI- 120 / 103 = 1.165
> >>>>>>>
> >>>>>>> EIGRP will round down to the nearest integer so the first path is
> >>>>>>> actually "1"
> >>>>>>>
> >>>>>>> I also believe the largest metric would have be a path being
> selected by
> >>>>>>> EIGRP for placement into the routing table.. If your route is not
> >>> selected
> >>>>>>> because the metric is larger than the
> >>>>>>> Variance x feasible distance.. I do not believe it will be
included
> in
> >>>>>>> the route traffic share calculation.
> >>>>>>>
> >>>>>>> HTH
> >>>>>>>
> >>>>>>> Garth
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>> On Sun, Sep 26, 2010 at 6:14 PM, Bilal Hansrod <
> >>>>>>> bilal.hansrod_at_gmail.com> wrote:
> >>>>>>>
> >>>>>>>> Hello Everyone,
> >>>>>>>>
> >>>>>>>> I am having difficulty calculating the EIGRP Traffic Share Count.
> As
> >>>>>>>> far as
> >>>>>>>> my understanding regarding Traffic Share Count is, you divide the
> >>>>>>>> largest
> >>>>>>>> metric with lowest to forward packets based on number. For
example
> >>>>>>>>
> >>>>>>>> A-X = Metric is 10
> >>>>>>>> B-X = Metric is 20
> >>>>>>>> C-X = Metric is 30
> >>>>>>>> D-X = Metric is 40
> >>>>>>>> E-X = Metric is 90
> >>>>>>>>
> >>>>>>>> If I configure variance 4, it means all above metric will be used
> for
> >>>>>>>> load
> >>>>>>>> balancing except E-X (90), because it does not fall under 80
> (Lowest
> >>>>>>>> Metric
> >>>>>>>> X 4). So when calculate, I still use E-X Metric for Traffic Share
> >>>>>>>> Count.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> A-X = Metric is 10 = Traffic Share Count (90/10) = 9
> >>>>>>>> B-X = Metric is 20 = Traffic Share Count (90/20) = 5
> >>>>>>>> C-X = Metric is 30 = Traffic Share Count (90/30) = 3
> >>>>>>>> D-X = Metric is 40 = Traffic Share Count (90/40) = 2
> >>>>>>>>
> >>>>>>>> It means 9 packets will be sent via A-X, 5 packets via B-X, 3
> packets
> >>>>>>>> via
> >>>>>>>> C-X, and 2 packets via D-X and round robin. Am I correct till
> here??
> >>>>>>>>
> >>>>>>>> Now, when I have below output, how is Traffic Share Count
> calculated
> >>>>>>>>
> >>>>>>>> Rack1R6#show ip route 155.1.9.9
> >>>>>>>> Routing entry for 155.1.9.0/24
> >>>>>>>> Known via "eigrp 100", distance 90, metric 3072, type internal
> >>>>>>>> Redistributing via eigrp 10, eigrp 100
> >>>>>>>> Advertised by eigrp 10
> >>>>>>>> Last update from 155.1.146.1 on FastEthernet0/0.146, 00:01:04 ago
> >>>>>>>> Routing Descriptor Blocks:
> >>>>>>>> 155.1.146.1, from 155.1.146.1, 00:01:04 ago, via
> FastEthernet0/0.146
> >>>>>>>> Route metric is 3584, traffic share count is 103
> >>>>>>>> Total delay is 140 microseconds, minimum bandwidth is 1544
> Kbit
> >>>>>>>> Reliability 255/255, minimum MTU 1500 bytes
> >>>>>>>> Loading 1/255, Hops 4
> >>>>>>>>
> >>>>>>>> * 155.1.67.7, from 155.1.67.7, 00:01:04 ago, via
> FastEthernet0/0.67
> >>>>>>>> Route metric is 3072, traffic share count is 120
> >>>>>>>> Total delay is 120 microseconds, minimum bandwidth is 100000
> Kbit
> >>>>>>>> Reliability 255/255, minimum MTU 1500 bytes
> >>>>>>>> Loading 1/255, Hops 2
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Anyone's help will be highly appreciated,
> >>>>>>>>
> >>>>>>>> Regards,
> >>>>>>>>
> >>>>>>>> Bilal
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Blogs and organic groups at http://www.ccie.net
<http://www.ccie.net/>
> >>>>>>>>
> >>>>>>>>
> _______________________________________________________________________
> >>>>>>>> Subscription information may be found at:
> >>>>>>>> http://www.groupstudy.com/list/CCIELab.html
> >>>
> >>>
> >>> Blogs and organic groups at http://www.ccie.net <http://www.ccie.net/>
> >>>
> >>>
Received on Wed Sep 29 2010 - 01:28:50 ART
This archive was generated by hypermail 2.2.0 : Fri Oct 01 2010 - 05:58:06 ART