how to achieve eigrp load balance?

[dannan lin]

hi:

base on the below topology, I have two questions about eigrp loadbalance.

first, why i can see the router to 5.0.0.0/24 in topology table but when i try to see the specific routes to 5.0.0.0 with command " show ip eigrp top 5.0.0.0" it says the route is not in the topology table.

can anyone help ?

Second question,

there are two routes to the 5.0.0.0/24 with different FD and RD ,

P 5.5.5.0/24, 1 successors, FD is 156160, serno 15

        via 1.1.1.1 (156160/128256), FastEthernet1/0

        via 3.3.3.4 (158720/156160), FastEthernet1/

in routing table it chooses the smallest FD as the best route which is via 1.1.1.1

D       5.5.5.0 [90/156160] via 1.1.1.1, 00:10:08, FastEthernet1/0

i want to know if i can force route 3.3.3.4 to join the routing table.

i have tried to use " variance" command but it didn't  work (why is that ?) 

please help me here.

much appreciated.

how do i add another router to 5.0.0.0 into routing table.

R1(config)#do show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     1.0.0.0/24 is subnetted, 1 subnets
C       1.1.1.0 is directly connected, FastEthernet1/0
     2.0.0.0/24 is subnetted, 1 subnets
D       2.2.2.0 [90/30720] via 3.3.3.4, 00:00:06, FastEthernet1/1
                [90/30720] via 1.1.1.1, 00:00:06, FastEthernet1/0
     3.0.0.0/24 is subnetted, 1 subnets
C       3.3.3.0 is directly connected, FastEthernet1/1
     5.0.0.0/24 is subnetted, 1 subnets
D       5.5.5.0 [90/156160] via 1.1.1.1, 00:00:06, FastEthernet1/0
R1(config)#do show ip eigrp top 5.0.0.0
% IP-EIGRP (AS 10): Route not in topology table
R1(config)#do show ip eigrp top all
IP-EIGRP Topology Table for AS(10)/ID(3.3.3.3)

Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - reply Status, s - sia Status

P 1.1.1.0/24, 1 successors, FD is 28160, serno 1
        via Connected, FastEthernet1/0
P 2.2.2.0/24, 2 successors, FD is 30720, serno 14
        via 1.1.1.1 (30720/28160), FastEthernet1/0
        via 3.3.3.4 (30720/28160), FastEthernet1/1
P 3.3.3.0/24, 1 successors, FD is 28160, serno 2
        via Connected, FastEthernet1/1
P 5.5.5.0/24, 1 successors, FD is 156160, serno 15
        via 1.1.1.1 (156160/128256), FastEthernet1/0

[cadet alain · Accepted solution]

Hi,

5.0.0.0 is the parent route( classful one) so you have to look for the child route(5.5.5.0/24) with the command  sh ip eigrp topology 5.5.5.0 255.255.255.0

i have tried to use " variance" command but it didn't  work (why is that ?)

the  path via 3.3.3.4 is not a feasible successor as the RD must strictly less than the FD of the successor and EIGRP will only install unequal cost routes if 2 conditions are met:

1) the other route must meet the feasibility condition

2) the FD of the feasible successor route must be less than or equal to the FD of the successor * variance

So you'll have to modify the delay to force the RD of second path to be less than the FD of successor and then the variance command will work.

Regards.

Alain

[Peter Paluch]

Hello Alain,

A nice reply!

Please allow me to have a remark regarding the EIGRP terminology that seems to be widespreadly wrong: there is no such thing as "FD of the successor" or "FD of the feasible successor". There is only a FD of the route itself, which is the lowest metric of the route since the last time of Active->Passive transition (i.e. not necessarily the current lowest metric, as that might be higher). Distances via particular neighbors do not have any special names and I use to call them Total Distances which is just my term.

Most certainly, however, it is incorrect to talk about FD as if it was relative to a particular neighbor. The FD is related only to the route itself, regardless of which neighbor provides or provided (in the past) such a good low metric.

I had an extensive discussion about the same terminology in another thread - you actually joined the discussion there, too:

https://supportforums.cisco.com/message/3527031#3527031

Best regards,

Peter

[cadet alain · Accepted solution]

Hi Peter,

Thanks but you know what they say bad habits are hard to wipe out  ,

but I'll revisit this discussion and read it thoroughly

Regards.

Alain

[Peter Paluch]

Hi Alain,

Yeah, I know about bad habits myself, I understand that completely Please allow me to assure you that I am not purposefully seeking out any flaws and I hugely respect your knowledge. Regarding the EIGRP, I am somewhat sensitive to it (to my own surprise), as I invested quite a lot of time into understanding it and understanding the theory behind it, and it suddenly struck me how many misconceptions are being spread about it in the public and even in some official publications. So I tend to point them out if I come across them.

I am seriously considering creating a document somewhere here called "Myths and truths about EIGRP"...

Best regards,

Peter

[Kishore Chennupati]

I would defintely recommend that you write up a doco peter and we wil simply keep re-visiting that everytime we have an eigrp query..

[dannan lin]

thank you guys.