This is where actual hands-on pays off. From a lot of docs you'll get the
impression that the topology table only stores the main route "sucessor" and
"feasible sucessors". Obviously from your output that is not the case.
You have 3 EIGRP neigbors that have a route for the 172.20.178.0/24 network.
The 172.20.100.1 is the next hop for the route that is in the routing table.
The Feasible Distance is 675072. The other two neigbors have metrics to the
network of 2330112 & 1789952. This router has NO "Feasible Successor"
because
the other two neigbors have metrics greater than the FD. If the 172.20.100.1
router is lost the route will go ACTIVE, and query all neighbors to see if
they
have metric that beats the FD of 675072. Since the other two neighbors
routes
are higher than the FD than this router will not accept them as the
"sucessor"
until the current route, next hop, FD, etc is flushed out of the routing
table.
You state: [Actually, there should be 5 routing path can reach the network
"172.20.178.0"]
With out knowing a lot more about the physical & logical topologies, and
seeing
all configs I can not give a guess as to why you do not have 5 neigbors with
a
route to 172.20.178.0/24.
DaveC
dovelet wrote:
>
> Hi all,
>
> I have a question about EIGRP Topology table. As I know, if there is many
> path can go to a network, the EIGRP topology table will only stores the
> route of the "Successor" and the "Feasible Successor". The path will become
> "Feasible Successor" if its "Reported Distance" is less than the "Feasible
> Distance". However, I found the following in my network:
>
>
----------------------------------------------------------------------------
> --------------------
> R1#show ip eigrp topology 172.20.178.0 255.255.255.0
> IP-EIGRP topology entry for 172.20.178.0 255.255.255.0
> State is Passive, Query origin flag is 1, 1 Successor(s), FD is 675072
> Routing Descriptor Blocks:
> 172.20.100.1 (Ethernet1), from 172.20.100.1, Send flag is 0x0
> Composite metric is (675072/649472), Route is Internal
> Vector metric:
> Minimum bandwidth is 6146 Kbit
> Total delay is 10100 microseconds
> Reliability is 255/255
> Load is 24/255
> Minimum MTU is 1500
> Hop count is 2
> 172.20.31.2 (Serial2), from 172.20.31.2, Send flag is 0x0
> Composite metric is (3258880/2330112), Route is Internal
> Vector metric:
> Minimum bandwidth is 1536 Kbit
> Total delay is 62200 microseconds
> Reliability is 255/255
> Load is 7/255
> Minimum MTU is 1500
> Hop count is 6
> 172.20.32.2 (Serial5), from 172.20.32.2, Send flag is 0x0
> Composite metric is (2462720/1789952), Route is Internal
> Vector metric:
> Minimum bandwidth is 1536 Kbit
> Total delay is 31100 microseconds
> Reliability is 255/255
> Load is 44/255
> Minimum MTU is 1500
> Hop count is 3
>
----------------------------------------------------------------------------
> -----------------
>
> When I show the EIGRP topology table in R1, it show 3 routes (I think 1 is
> the Successor and 2 are the Feasible Successor). Actually, there should be
5
> routing path can reach the network "172.20.178.0", it only display 3 of
> them, I think it is due to the other 2 have greater "Reported Distance" and
> they cannot become the "Feasible Successor". Is that true?
> My another question is: when R1 go to network "172.20.178.0", it chooses
the
> router "172.20.100.1" and the "Feasible Distance" is 675072. The "Reported
> Distance" of the path through the router "172.20.31.2" and "172.20.32.2"
are
> "2330112" and "1789952" which are much greater than the "Feasible
Distance".
> They should not be stored in the topology table. How come they will
> displayed in the table? Please help.
>
> Regards.
> dovelet
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