Again, your math being off by 500 makes me wonder if you're just forgetting about the 500 delay units that the loopback contributes on the originating router...
On Tue, Dec 27, 2011 at 5:05 PM, Bodnar, Edward <[email protected]>wrote: > Ya there in there. Just the math doe sot add up for me. I can get it to > work but my math is off by 500. I am sure it works I am just having issues > with the formula to calculate. > > -----Original Message----- > From: Dwann Hall [mailto:[email protected]] > Sent: Tuesday, December 27, 2011 5:04 PM > To: Bob McCouch > Cc: Bodnar, Edward; [email protected] > Subject: Re: [OSL | CCIE_RS] Not sure if anybody can help with an EIGRP > question > > Thanks for the good info Bob! @Ed - Are the other routes in the > topology table before you do your variance command? -d > > On Tue, Dec 27, 2011 at 4:48 PM, Bob McCouch <[email protected]> wrote: > > Hey Ed, > > > > I just tested this out and didn't run into any problem: > > > > R1(config-router)#do sh ip eigrp top 3.3.3.3/32 > >> EIGRP-IPv4 Topology Entry for AS(1)/ID(1.1.1.1) for 3.3.3.3/32 > >> State is Passive, Query origin flag is 1, 2 Successor(s), FD is 153600 > >> Descriptor Blocks: > >> 10.1.13.3 (Ethernet0/0), from 10.1.13.3, Send flag is 0x0 > >> *Composite metric is (153600/128000)*, route is Internal > >> Vector metric: > >> Minimum bandwidth is 100000 Kbit > >> *Total delay is 6000 microseconds* > >> Reliability is 255/255 > >> Load is 1/255 > >> Minimum MTU is 1500 > >> Hop count is 1 > >> Originating router is 3.3.3.3 > >> 10.2.13.3 (Serial1/1), from 10.2.13.3, Send flag is 0x0 > >> *Composite metric is (640000/128000)*, route is Internal > >> Vector metric: > >> Minimum bandwidth is 1544 Kbit > >> *Total delay is 25000 microseconds* > >> Reliability is 255/255 > >> Load is 1/255 > >> Minimum MTU is 1500 > >> Hop count is 1 > >> Originating router is 3.3.3.3 > >> R1(config-router)#do sh ip ro 3.3.3.3 > >> Routing entry for 3.3.3.3/32 > >> Known via "eigrp 1", distance 90, metric 153600, type internal > >> Redistributing via eigrp 1 > >> Last update from 10.2.13.3 on Serial1/1, 00:00:17 ago > >> Routing Descriptor Blocks: > >> 10.2.13.3, from 10.2.13.3, 00:00:17 ago, via Serial1/1 > >> Route metric is 640000, *traffic share count is 29* > >> Total delay is 25000 microseconds, minimum bandwidth is 1544 Kbit > >> Reliability 255/255, minimum MTU 1500 bytes > >> Loading 1/255, Hops 1 > >> * 10.1.13.3, from 10.1.13.3, 00:00:17 ago, via Ethernet0/0 > >> Route metric is 153600, *traffic share count is 120* > >> Total delay is 6000 microseconds, minimum bandwidth is 100000 Kbit > >> Reliability 255/255, minimum MTU 1500 bytes > >> Loading 1/255, Hops 1 > > > > > > > > > > After setting variance to 5, my traffic share was 120:29, or 4.14:1 which > > was the closest the calculation could get to the exact metric ratio of > > 640000/153600=4.166666667 > > > > In my setup here, in order to get the share exactly 5:1, I need to > actually > > increase my worse metric. I need it to be 5*153600=768000. I originally > > started using an offset list when labbing this, but that screwed me up by > > causing the second path to fail the FC since an offset list does its work > > by increasing the delay component of the RD. I backed off of that and > just > > added delay to the serial interface on R1 (where I was trying to achieve > > the 5:1 ratio). > > > > 768000/256=3000 delay units, or 30,000 usec. You can see from the topo > > output above that the route via s1/1 currently has "Total delay is 25000 > > microseconds", so I need to bump the interface delay up by 500 delay > units, > > or 5000 usec: > > > > R1(config-router)#int s1/1 > >> R1(config-if)#delay ? > >> <1-16777215> Throughput delay (tens of microseconds) > >> R1(config-if)#delay 2500 > >> R1(config-if)#exit > > > > > > In my lab, I had to clear the EIGRP adjacencies to get it to redo the > > calculation, but it did work as expected: > > > > R1(config)#do sh ip eigrp top 3.3.3.3/32 > >> EIGRP-IPv4 Topology Entry for AS(1)/ID(1.1.1.1) for 3.3.3.3/32 > >> State is Passive, Query origin flag is 1, 2 Successor(s), FD is 153600 > >> Descriptor Blocks: > >> 10.1.13.3 (Ethernet0/0), from 10.1.13.3, Send flag is 0x0 > >> *Composite metric is (153600/128000)*, route is Internal > >> Vector metric: > >> Minimum bandwidth is 100000 Kbit > >> *Total delay is 6000 microseconds* > >> Reliability is 255/255 > >> Load is 1/255 > >> Minimum MTU is 1500 > >> Hop count is 1 > >> Originating router is 3.3.3.3 > >> 10.2.13.3 (Serial1/1), from 10.2.13.3, Send flag is 0x0 > >> *Composite metric is (768000/128000)*, route is Internal > >> Vector metric: > >> Minimum bandwidth is 1544 Kbit > >> *Total delay is 30000 microseconds* > >> Reliability is 255/255 > >> Load is 1/255 > >> Minimum MTU is 1500 > >> Hop count is 1 > >> Originating router is 3.3.3.3 > >> R1(config)#do sh ip ro 3.3.3.3 > >> Routing entry for 3.3.3.3/32 > >> Known via "eigrp 1", distance 90, metric 153600, type internal > >> Redistributing via eigrp 1 > >> Last update from 10.2.13.3 on Serial1/1, 00:00:33 ago > >> Routing Descriptor Blocks: > >> 10.2.13.3, from 10.2.13.3, 00:00:33 ago, via Serial1/1 > >> Route metric is 768000, *traffic share count is 1* > >> Total delay is 30000 microseconds, minimum bandwidth is 1544 Kbit > >> Reliability 255/255, minimum MTU 1500 bytes > >> Loading 1/255, Hops 1 > >> * 10.1.13.3, from 10.1.13.3, 00:00:33 ago, via Ethernet0/0 > >> Route metric is 153600, *traffic share count is 5* > >> Total delay is 6000 microseconds, minimum bandwidth is 100000 Kbit > >> Reliability 255/255, minimum MTU 1500 bytes > >> Loading 1/255, Hops 1 > > > > > > > > Places you might watch out for when working the math: > > > > 1) Remember that bandwidth is minimum in the path, but delay is > cumulative. > > Based on your problem described below, I'm wondering if you already had > the > > other 5050 usec of delay elsewhere in the path. You'd need the total > delay > > to be 2505 delay units (25050 usec), so if you already have 5000 usec > from > > the loopback interface you're advertising and 50 usec from > > I-don't-know-where, that's why you had to set your interface bandwidth > back > > to 2000 to get it to work the way you wanted. > > > > 2) Remember also that EIGRP does purely integer math when calculating > > metrics. Decimals are truncated (not rounded) at each step of the > > arithmetic. I don't think that's what's getting you here necessarily, but > > I've been stumped on that before when trying to back my way into the > metric > > calculation. When you have bandwidth in the mix and the metric is in the > > millions or tens of millions, a couple decimal values that you include > when > > manually calculating the metric will cause your hand-calculated value to > be > > off by a mysterious 40 or 220 or something. > > > > Good luck, > > Bob > > > > > > On Tue, Dec 27, 2011 at 1:29 PM, Bodnar, Edward < > [email protected]>wrote: > > > >> I can never seem to get the math to work on calculating an EIGRP unequal > >> cost ratio. > >> > >> I set my weights so I am using just delay to try to make it easier and I > >> still can't seem to work it out. > >> > >> 2 routers directly connected in GNS3 one serial link one Ethernet. > >> > >> What I am trying for a 5-1 ratio > >> > >> Locate the lower metric ( 128256 ) * by 5 = 641280 > >> > >> > >> So BW is out of play > >> > >> Delay is set to 1 > >> > >> 641280 = dlay * 256 > >> > >> So 641280 / 256 = 2505 > >> > >> But I have to set my interface to Delay 2000 in order to get the 5-1 > ratio. > >> > >> Not sure what I am missing. > >> > >> > >> _______________________________________________ > >> For more information regarding industry leading CCIE Lab training, > please > >> visit www.ipexpert.com > >> > >> Are you a CCNP or CCIE and looking for a job? Check out > >> www.PlatinumPlacement.com > >> > >> http://onlinestudylist.com/mailman/listinfo/ccie_rs > >> > > _______________________________________________ > > For more information regarding industry leading CCIE Lab training, > please visit www.ipexpert.com > > > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > > > > http://onlinestudylist.com/mailman/listinfo/ccie_rs > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
