EIGRP Offset list command secrets by cciepursuit ~ CCNP, CCSP and CCIE Security Version 4 Training Institute in India- Delhi

The following post is loooooong and of no interest to 99.9999999999% of the world. I was going over EIGRP commands and had a problem with an EIGRP offset-list not altering the EIGRP metric the way that it should have. In the process of playing with this command I think that I’ve found the method that this command uses to alter the EIGRP metric of a route.
I did warn you that this was only interesting to a handful of geeks.
Here’s the network topology. Really basic:
r1————r2
r1 and r2 are connected by a single serial link (s0/0 on both devices). Both routers running EIGRP on all interfaces. There are 3 loopbacks being advertised on each device.

r1#sh ip ei int
IP-EIGRP interfaces for process 100

Xmit Queue   Mean   Pacing Time   Multicast    Pending
Interface        Peers Un/Reliable SRTT   Un/Reliable   Flow Timer   Routes
Se0/0 1 0/0        27       0/15          91           0
Lo0                0        0/0         0       0/10           0           0
Lo1                0        0/0         0       0/10           0           0
Lo2                0        0/0         0       0/10           0           0

r1#sh ip ei nei
IP-EIGRP neighbors for process 100
H   Address                 Interface       Hold Uptime   SRTT   RTO Q Seq
(sec)         (ms)       Cnt Num
0   10.1.12.2 Se0/0 13 00:01:47   27   200 0 3

r1#sh ip route ei
D    222.222.222.0/24 [90/2297856] via 10.1.12.2, 00:01:55, Serial0/0
2.0.0.0/24 is subnetted, 1 subnets
D       2.2.2.0 [90/2297856] via 10.1.12.2, 00:01:55, Serial0/0
22.0.0.0/24 is subnetted, 1 subnets
D       22.22.22.0 [90/2297856] via 10.1.12.2, 00:01:55, Serial0/0

r2#sh ip ei int
IP-EIGRP interfaces for process 100

Xmit Queue   Mean   Pacing Time   Multicast    Pending
Interface        Peers Un/Reliable SRTT   Un/Reliable   Flow Timer   Routes
Se0/0 1 0/0        34       0/15         147           0
Lo0                0        0/0         0       0/10           0           0
Lo1                0        0/0         0       0/10           0           0
Lo2                0        0/0         0       0/10           0           0

r2#sh ip ei nei
IP-EIGRP neighbors for process 100
H   Address                 Interface       Hold Uptime   SRTT   RTO Q Seq
(sec)         (ms)       Cnt Num
0   10.1.12.1 Se0/0 13 00:02:15   34   204 0 3

r2#sh ip route ei
1.0.0.0/24 is subnetted, 1 subnets
D       1.1.1.0 [90/2297856] via 10.1.12.1, 00:02:19, Serial0/0
111.0.0.0/24 is subnetted, 1 subnets
D       111.111.111.0 [90/2297856] via 10.1.12.1, 00:02:19, Serial0/0
11.0.0.0/24 is subnetted, 1 subnets
D       11.11.11.0 [90/2297856] via 10.1.12.1, 00:02:19, Serial0/0

Okay to start with let’s see the routing information for net 1.1.1.0/24 on r2:

r2#sh ip route 1.1.1.0
Routing entry for 1.1.1.0/24
Known via “eigrp 100″, distance 90, metric 2297856, type internal
Redistributing via eigrp 100
Last update from 10.1.12.1 on Serial0/0, 00:03:17 ago
Routing Descriptor Blocks:
* 10.1.12.1, from 10.1.12.1, 00:03:17 ago, via Serial0/0
Route metric is 2297856, traffic share count is 1
Total delay is 25000 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

On r2 let’s add 100 to the EIGRP metrics of all EIGRP routes advertised in s0/0 from r1:
[NOTE: access-list 0 selects all networks]

r2(config)#router ei 100
r2(config-router)#offset-list 0 in 100 s0/0

*Mar 1 00:15:01.055: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.1.12.1 (Serial0/0) is resync: route configuration changed

r2(config-router)#do sh ip route 1.1.1.0
Routing entry for 1.1.1.0/24
Known via “eigrp 100″, distance 90, metric 2297956, type internal
Redistributing via eigrp 100
Last update from 10.1.12.1 on Serial0/0, 00:00:08 ago
Routing Descriptor Blocks:
* 10.1.12.1, from 10.1.12.1, 00:00:08 ago, via Serial0/0
Route metric is 2297956, traffic share count is 1
Total delay is 25003 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

Interesting…we’ve added 100 to the EIGRP metric as expected. The ‘total delay’ has also increased by 3 microseconds (not expected). It seems that the EIGRP offset-list alters the EIGRP variable in order to change the overall EIGRP metric. EIGRP uses this easy to remember

equation to calculate its metric:

If k5 equals 0, the composite EIGRP metric is computed according to the following formula:
metric = [k1 * bandwidth + (k2 * bandwidth)/(256 - load) + k3 * delay]

If k5 does not equal zero, an additional operation is performed:
metric = metric * [k5/(reliability + k4)]

This led me to wonder what would happen if we took delay out of the EIGRP equation. We can do that by setting the EIGRP K-Value for delay to 0 and just leaving bandwidth K-Value (we’ll need to do this on both routers):

r1(config)# router ei 100
r1(config-router)# metric weights 0 1 0 0 0 0

r2(config)#router ei 100
r2(config-router)#metric weights 0 1 0 0 0 0
r2(config-router)#no offset-list 0 in 100 s0/0

r2(config-router)#do sh ip proto | i EIGRP metric weight
EIGRP metric weight K1=1, K2=0, K3=0, K4=0, K5=0

Let’s see our metric before applying the offset-list:

r2(config-router)#do sh ip route 1.1.1.0
Routing entry for 1.1.1.0/24
Known via “eigrp 100″, distance 90, metric 1657856, type internal
Redistributing via eigrp 100
Last update from 10.1.12.1 on Serial0/0, 00:00:32 ago
Routing Descriptor Blocks:
* 10.1.12.1, from 10.1.12.1, 00:00:32 ago, via Serial0/0
Route metric is 1657856, traffic share count is 1
Total delay is 25000 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

Okay, let’s reapply the offset-list:

r2(config-router)#offset-list 0 in 100 s0/0

*Mar 1 03:04:44.711: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.1.12.1 (Serial0/0) is resync: route configuration changed

r2(config-router)#do sh ip route 1.1.1.0
Routing entry for 1.1.1.0/24
Known via “eigrp 100″, distance 90, metric 1657856, type internal
Redistributing via eigrp 100
Last update from 10.1.12.1 on Serial0/0, 00:00:10 ago
Routing Descriptor Blocks:
* 10.1.12.1, from 10.1.12.1, 00:00:10 ago, via Serial0/0
Route metric is 1657856, traffic share count is 1
Total delay is 25003 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

BOOYAH! The offset-list is supposed to increase the EIGRP metric by 100. We can see that the metric did NOT change (still 1657856), BUT the total delay increased by 3 microseconds. It looks like we’ve discovered the mechanism used by the EIGRP offset-list to change the EIGRP metric. We’ve also discovered that setting the delay K-Value to zero “breaks” the offset-list function.
One last experiment. Let’s see if the offset-list is intelligent enough to handle a delay K-Value of more than 1:

r1(config-router)#metric weights 0 1 0 4 0 0

r2(config-router)#metric weights 0 1 0 4 0 0
r2(config-router)#no offset-list 0 in 100 s0/0

r2(config-router)#do sh ip proto | i EIGRP metric weight
EIGRP metric weight K1=1, K2=0, K3=4, K4=0, K5=0

r2(config-router)#do sh ip route 1.1.1.0
Routing entry for 1.1.1.0/24
Known via “eigrp 100″, distance 90, metric 4217856, type internal
Redistributing via eigrp 100
Last update from 10.1.12.1 on Serial0/0, 00:01:09 ago
Routing Descriptor Blocks:
* 10.1.12.1, from 10.1.12.1, 00:01:09 ago, via Serial0/0
Route metric is 4217856, traffic share count is 1
Total delay is 25000 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

r2(config-router)#offset-list 0 in 100 s0/0

*Mar 1 03:11:56.439: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.1.12.1 (Serial0/0) is resync: route configuration changed

r2(config-router)#do sh ip route 1.1.1.0
Routing entry for 1.1.1.0/24
Known via “eigrp 100″, distance 90, metric 4218256, type internal
Redistributing via eigrp 100
Last update from 10.1.12.1 on Serial0/0, 00:00:07 ago
Routing Descriptor Blocks:
* 10.1.12.1, from 10.1.12.1, 00:00:07 ago, via Serial0/0
Route metric is 4218256, traffic share count is 1
Total delay is 25003 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

Weird. I would have thought that this would have worked as we have our default K-Values but have just increased the weight of delay 4 times. We can see that the delay was once again increased by 3 microseconds, but the overall metric was unaffected. Weird.

Thank you to reader Rich for pointing out that 4217856 and 4218256 are NOT the same value.

The EIGRP metric increased by 400 instead of the 100 that we specified in the offset-list. That’s because the K-Value for delay is set to 4 times the default.

Hmmm…one more experiment. Let’s set the delay K-Value back to 1 but make it the only variable used for the EIGRP metric:

r1(config-router)#metric weights 0 0 0 1 0 0

r2(config-router)#metric weights 0 0 0 1 0 0
r2(config-router)#no offset-list 0 in 100 s0/0

r2(config-router)#do sh ip proto | i EIGRP metric weight
EIGRP metric weight K1=0, K2=0, K3=1, K4=0, K5=0

r2(config-router)#do sh ip route 1.1.1.0
Routing entry for 1.1.1.0/24
Known via “eigrp 100″, distance 90, metric 640000, type internal
Redistributing via eigrp 100
Last update from 10.1.12.1 on Serial0/0, 00:00:33 ago
Routing Descriptor Blocks:
* 10.1.12.1, from 10.1.12.1, 00:00:33 ago, via Serial0/0
Route metric is 640000, traffic share count is 1
Total delay is 25000 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

Let’s reapply the offset-list and see what happens:

r2(config-router)#offset-list 0 in 100 s0/0

*Mar 1 03:22:54.319: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.1.12.1 (Serial0/0) is resync: route configuration changed

r2(config-router)#do sh ip route 1.1.1.0
Routing entry for 1.1.1.0/24
Known via “eigrp 100″, distance 90, metric 640100, type internal
Redistributing via eigrp 100
Last update from 10.1.12.1 on Serial0/0, 00:00:06 ago
Routing Descriptor Blocks:
* 10.1.12.1, from 10.1.12.1, 00:00:06 ago, via Serial0/0
Route metric is 640100, traffic share count is 1
Total delay is 25003 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

It worked. So we don’t need to have the bandwidth K-Value “turned on” for the offset-list to work.
Last experiment…I promise. Let’s set the delay K-Value to 4 and set the other K-Values to 0:

r1(config-router)#metric weights 0 0 0 4 0 0

r2(config-router)#metric weights 0 0 0 4 0 0
r2(config-router)#no offset-list 0 in 100 s0/0

r2(config-router)#do sh ip proto | i EIGRP metric weight
EIGRP metric weight K1=0, K2=0, K3=4, K4=0, K5=0

r2(config-router)#do sh ip route 1.1.1.0
Routing entry for 1.1.1.0/24
Known via “eigrp 100″, distance 90, metric 2560000, type internal
Redistributing via eigrp 100
Last update from 10.1.12.1 on Serial0/0, 00:00:14 ago
Routing Descriptor Blocks:
* 10.1.12.1, from 10.1.12.1, 00:00:14 ago, via Serial0/0
Route metric is 2560000, traffic share count is 1
Total delay is 25000 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

Reapply the offset-list:

r2(config-router)#offset-list 0 in 100 s0/0

*Mar 1 03:33:52.279: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.1.12.1 (Serial0/0) is resync: route configuration changed

r2(config-router)#do sh ip route 1.1.1.0
Routing entry for 1.1.1.0/24
Known via “eigrp 100″, distance 90, metric 2560400, type internal
Redistributing via eigrp 100
Last update from 10.1.12.1 on Serial0/0, 00:00:06 ago
Routing Descriptor Blocks:
* 10.1.12.1, from 10.1.12.1, 00:00:06 ago, via Serial0/0
Route metric is 2560400, traffic share count is 1
Total delay is 25003 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

Ah hah! The metric changed by 400 instead of 100 (as we had configured it to be offset). I think that this is pretty good evidence that the EIGRP offset-list only alters the EIGRP delay variable and is only accurate when that K-Value is set to 1.
I don’t think that this will affect you in real life (who’s changing K-Values and using offset-lists with EIGRP?) but it could possibly come up in a lab. I could forsee a task that has you change the K-Values and then another task that has you altering EIGRP metrics (probably for some evil unequal-cost load-balancing task). At least now you’ll know why your perfectly executed offset-list solution has failed.

Network Bulls
Best Institute for CCNA CCNP CCSP CCIP CCIE R&S, CCIE Security Training in India
www.networkbulls.com
M-44, Old Dlf, Sector-14
Gurgaon, Haryana, india

About US

Network Bulls is Best Institute for Cisco CCNA, CCNA Security, CCNA Voice, CCNP, CCNP Security, CCNP Voice, CCIP, CCIE RS, CCIE Security Version 4 and CCIE Voice Certification courses in India. Network Bulls is a complete Cisco Certification Training and Course Coaching Institute in Gurgaon/Delhi NCR region in India. Network Bulls has Biggest Cisco Training labs in India. Network Bulls offers all Cisco courses on Real Cisco Devices. Network Bulls has Biggest Team of CCIE Trainers in North India, with more than 90% of passing rate in First Attempt for CCIE Security Version 4 candidates.

Biggest Cisco Training Labs in India
More than 90% Passing Rate in First Attempt
CCIE Certified Trainers for All courses
24x7 Lab Facility
100% Job Guaranteed Courses
Awarded as Best Network Security Institute in 2011 by Times
Only Institute in India, to provide CCIE Security Version 4.0 Training
CCIE Security Version 4 Training available
Latest equipments available for CCIE Security Version 4

Network Bulls Institute Gurgaon

Network Bulls Institute in Gurgaon is one of the best Cisco Certifications Training Centers in India. Network Bulls has Biggest Networking Training and Networking courses labs in North India. Network Bulls is offering Cisco Training courses on real Cisco Routers and Switches. Labs of Network Bulls Institute are 24x7 Available. There are many coaching Centers in Delhi, Gurgaon, Chandigarh, Jaipur, Surat, Mumbai, Bangalore, Hyderabad and Chennai, who are offering Cisco courses, but very few institutes out of that big list are offering Cisco Networking Training on real Cisco devices, with Live Projects. Network Bulls is not just an institute. Network Bulls is a Networking and Network Security Training and consultancy company, which is offering Cisco certifications Training as well support too. NB is awarded in January 2012, by Times, as Best Network Security and Cisco Training Institute for the year 2011. Network Bulls is also offering Summer Training in Gurgaon and Delhi. Network Bulls has collaboration with IT companies, from which Network Bulls is offering Networking courses in Summer Training and Industrial Training of Btech BE BCA MCA students on real Live projects. Job Oriented Training and Industrial Training on Live projects is also offered by network bulls in Gurgaon and Delhi NCR region. Network Bulls is also providing Cisco Networking Trainings to Corporates of Delhi, Gurgaon, bangalore, Jaipur, Nigeria, Chandigarh, Mohali, Haryana, Punjab, Bhiwani, Ambala, Chennai, Hyderabad.
Cisco Certification Exams are also conducted by Network Bulls in its Gurgaon Branch.
Network Bulls don't provide any Cisco CCNA, CCNP simulations for practice. They Provide High End Trainings on Real topologies for high tech troubleshooting on real Networks. There is a list of Top and best Training Institutes in India, which are providing CCNA and CCNP courses, but NB has a different image from market. Many students has given me their feedbacks and reviews about Network bulls Institute, but there were no complaints about any fraud from this institute. Network Bulls is such a wonderful place to get trained from Industry expert Trainers, under guidance of CCIE Certified Engineers.

CCIE Security Version 4

Cisco Finally updated CCIE Security Lab exam blueprint. WSA Ironport and ISE devices are added in CCIE Security Version 4 Lab Exam Syllabus Blueprint. In Updated CCIE Security Version 4 Syllabus blueprint, new technologies like Mobile Security, VoIP Security and IPV6 Security along with Network Security, are added. As in CCIE Security Version 3 blueprint, Cisco had focused on Network Security only, but now as per market demand, Cisco is looking forward to produce Internet gear Security Engineer, not only Network Security engineers.
In CCIE Security Version 4 Bluerpint, Lab Exam is going to be more interested than before. What is Difference in CCIE Security Version 3 and Version 4? Just go through the CCIE Security Version 4 Lab Equipment and Lab Exam Syllabus Blueprints and find out!

About NB

Network Bulls is Best institute for cisco certifications training in gurgaon. Network Bulls: A Complete CISCO Security Training Institute in Delhi/NCR, Gurgaon. Network Bulls provides Class Room, Online, One to One and Boot camp training on CCNA, CCNP, CCNA Security, CCNA Voice, CCSP, CCIE R&S, CCIE Security. Network Bulls is India's top CCIE (Cisco Certified Internetwork Expert) bootcamps, online classes and expert technical training Provider. Network Bulls provides ccna training in gurgaon. best ccnp training in gurgaon and bootcamp training for ccie written and lab certification in fast track, slow track and normal track for freshers and experienced candidates. NB is best ccie training institute in india. if anyone reallly interested doing quality training of cisco CCIE security Version 4, than i will recommend NB for CCIE Security Version 4 Training in India. CCIE Security Version 4 is highest level Certification offered by Cisco Systems, in Network Security track. All new devices of CCIE Security Version 4, are available in Network Bulls Gurgaon.

About Network Bulls Gurgaon

Best institute for ccna, ccnp, ccsp and ccie security version 4 course training in Delhi and Gurgaon.
Which is best ccsp institute in delhi? cisco certified security professional training in delhi ncr gurgaon. Nb provides world class top training for cisco security firewall in delhi ncr. Cisco CCIE certification exam lab asia's biggest lab training institution in new delhi gurgaon india. There are many institutes in India, who claims to provide Job Guarantee after CCNA even. There are some small institutes, who make fool of students with there cheap tricks and frauds. Some institutes in this field, do not have CCIE Certified trainers and racks available, but they claim to provide best training from other big institutes. Student should not take admission in such fraud and cheap institutes. Students can also give their valuable feedback, complaints and reviews about different institutes in our forums. But students should also be aware of wrong and unauthenticated feedback or complaints against great institutes like Network Bulls, Networkers Home and INE in some fake complaint forums, where no one is authenticating any comment or posts. Those wrong posts are written by some competitor institutes only. Those cheap and fraud institutes can't earn money and get admissions based on their results and infrastructure. They just write rubbish and wrong things on different forums against some good institutes and try to get admissions. A student who want to get refunds or good training or want to give feedback, can also go to consumer court and register a complaint against that fraud institute.
As per my experience Network Bulls and INE are both the best institutes of world.