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
