successor repost...

not going through this again...

Thursday, December 15, 2011

successor excess...

a successor route is the lowest cost/best path that EIGRP is currently using...  this route shows up in the neighbor table, the topology table, and the route table...

r2620_01(config-if)#do sh ip route eigrp
     2.0.0.0/24 is subnetted, 1 subnets
D       2.2.2.0 [90/156160] via 192.168.1.120, 00:07:32, FastEthernet0/0
     100.0.0.0/24 is subnetted, 1 subnets
D       100.0.0.0 [90/156160] via 192.168.1.100, 00:07:32, FastEthernet0/0
     3.0.0.0/24 is subnetted, 1 subnets
D       3.3.3.0 [90/156160] via 192.168.1.130, 00:07:32, FastEthernet0/0
r2620_01(config-if)#

r2620_01(config-if)#do sh ip eigrp topo
IP-EIGRP Topology Table for AS(1)/ID(1.1.1.1)
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 128256
        via Connected, Loopback0
P 2.2.2.0/24, 1 successors, FD is 156160
        via 192.168.1.120 (156160/128256), FastEthernet0/0
        via 10.0.20.2 (2297856/128256), Serial0/0
P 3.3.3.0/24, 1 successors, FD is 156160
        via 192.168.1.130 (156160/128256), FastEthernet0/0
        via 10.0.30.2 (2297856/128256), Serial0/1
P 10.0.30.0/24, 1 successors, FD is 2169856
        via Connected, Serial0/1
P 10.0.30.1/32, 0 successors, FD is Inaccessible
        via 192.168.1.130 (2172416/2169856), FastEthernet0/0
        via 10.0.20.2 (2684416/2172416), Serial0/0
        via 10.0.30.2 (2681856/2169856), Serial0/1
P 10.0.30.2/32, 1 successors, FD is 2169856
        via Rconnected (2169856/0)
P 10.0.20.2/32, 1 successors, FD is 2169856
        via Rconnected (2169856/0)
P 10.0.20.0/24, 1 successors, FD is 2169856
        via Connected, Serial0/0
P 10.0.20.1/32, 0 successors, FD is Inaccessible
        via 192.168.1.120 (2172416/2169856), FastEthernet0/0
        via 10.0.30.2 (2684416/2172416), Serial0/1
        via 10.0.20.2 (2681856/2169856), Serial0/0
P 100.0.0.0/24, 1 successors, FD is 156160
        via 192.168.1.100 (156160/128256), FastEthernet0/0
P 192.168.1.0/24, 1 successors, FD is 28160
        via Connected, FastEthernet0/0
r2620_01(config-if)#

and:
r2620_01(config-if)#do sh ip eigrp neigh
IP-EIGRP neighbors for process 1
H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
                                            (sec)         (ms)       Cnt Num
4   192.168.1.130           Fa0/0             14 00:14:53   11   200  0  67
1   192.168.1.100           Fa0/0             12 00:14:53    8   200  0  92
0   192.168.1.120           Fa0/0             14 00:14:53 1030  5000  0  145
3   10.0.30.2                   Se0/1             11 00:47:52    3   200  0  68
2   10.0.20.2                   Se0/0             11 00:53:08    4   200  0  144
r2620_01(config-if)#

there seems to be confusion about the successor and the feasible successor...  certainly not to be confused with active in the topology table, which is according to hoyle:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml#neighbor_table


When there are no feasible successors, a route goes into Active state and a route recomputation occurs. A route recomputation commences with a router sending a query packet to all neighbors. Neighboring routers can either reply if they have feasible successors for the destination or optionally return a query indicating that they are performing a route recomputation. While in Active state, a router cannot change the next-hop neighbor it is using to forward packets. Once all replies are received for a given query, the destination can transition to Passive state and a new successor can be selected. 




the successor shows up in the route table, the topology table and the neighbor table, and the feasible successor shows in only the topology and neighbor tables


now lets eliminate the ethernet link to the layer 3 switch and reexamine 


r2620_01(config)#int fa0/0
r2620_01(config-if)#shut
r2620_01(config-if)#
Dec 15 16:23:09.798: IP-EIGRP(Default-IP-Routing-Table:1): conn_summary_depend:
FastEthernet0/0 192.168.1.0/24 0
r2620_01(config-if)#
Dec 15 16:23:09.798: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 192.168.1.130 (F
astEthernet0/0) is down: interface down
Dec 15 16:23:09.802: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 192.168.1.100 (F
astEthernet0/0) is down: interface down
Dec 15 16:23:09.806: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 192.168.1.120 (F
astEthernet0/0) is down: interface down
r2620_01(config-if)#
Dec 15 16:23:11.778: %LINK-5-CHANGED: Interface FastEthernet0/0, changed state t
o administratively down
Dec 15 16:23:12.778: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEtherne
t0/0, changed state to down
r2620_01(config-if)#
then
r2620_01(config-if)#do sh ip route eigrp
     2.0.0.0/24 is subnetted, 1 subnets
D       2.2.2.0 [90/2297856] via 10.0.20.2, 00:01:37, Serial0/0
     100.0.0.0/24 is subnetted, 1 subnets
D       100.0.0.0 [90/2300416] via 10.0.30.2, 00:01:37, Serial0/1
                  [90/2300416] via 10.0.20.2, 00:01:37, Serial0/0
     3.0.0.0/24 is subnetted, 1 subnets
D       3.3.3.0 [90/2297856] via 10.0.30.2, 00:01:37, Serial0/1
D    192.168.1.0/24 [90/2172416] via 10.0.30.2, 00:01:37, Serial0/1
                    [90/2172416] via 10.0.20.2, 00:01:37, Serial0/0
r2620_01(config-if)#


r2620_01(config-if)#do sh ip eigrp topo
IP-EIGRP Topology Table for AS(1)/ID(1.1.1.1)
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 128256
        via Connected, Loopback0
P 2.2.2.0/24, 1 successors, FD is 156160
        via 10.0.20.2 (2297856/128256), Serial0/0
P 3.3.3.0/24, 1 successors, FD is 156160
        via 10.0.30.2 (2297856/128256), Serial0/1
P 10.0.30.0/24, 1 successors, FD is 2169856
        via Connected, Serial0/1
P 10.0.30.1/32, 0 successors, FD is Inaccessible
        via 10.0.20.2 (2684416/2172416), Serial0/0
        via 10.0.30.2 (2681856/2169856), Serial0/1
P 10.0.30.2/32, 1 successors, FD is 2169856
        via Rconnected (2169856/0)
P 10.0.20.2/32, 1 successors, FD is 2169856
        via Rconnected (2169856/0)
P 10.0.20.0/24, 1 successors, FD is 2169856
        via Connected, Serial0/0
P 10.0.20.1/32, 0 successors, FD is Inaccessible
        via 10.0.30.2 (2684416/2172416), Serial0/1
        via 10.0.20.2 (2681856/2169856), Serial0/0
P 100.0.0.0/24, 2 successors, FD is 2300416
        via 10.0.20.2 (2300416/156160), Serial0/0
        via 10.0.30.2 (2300416/156160), Serial0/1
P 192.168.1.0/24, 2 successors, FD is 2172416
        via 10.0.20.2 (2172416/28160), Serial0/0
        via 10.0.30.2 (2172416/28160), Serial0/1
r2620_01(config-if)#


r2620_01(config-if)#do sh ip eigrp neigh
IP-EIGRP neighbors for process 1
H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
                                            (sec)         (ms)       Cnt Num
3   10.0.30.2               Se0/1             11 01:13:34    2   200  0  71
2   10.0.20.2               Se0/0             10 01:18:50    3   200  0  149
r2620_01(config-if)#

the feasible's have become the successors and now they are showing up in all three tables
so there...

Posted by arteq at Thursday, December 15, 2011