EIGRP Summary question

Hi,

I am at page 462 in the first workbook.

R4 and R5 are linked via one FR connection and also directly

I notice the following:

R4

interface Serial0/0.1 point-to-point
 ip address 155.1.0.4 255.255.255.0
 ip authentication mode eigrp 100 md5
 ip authentication key-chain eigrp 100 KEY_ROTATION
 ip summary-address eigrp 100 30.0.0.0 255.252.0.0 5
 frame-relay interface-dlci 405
interface Serial0/1
 ip address 155.1.45.4 255.255.255.0
 ip summary-address eigrp 100 31.0.0.0 255.252.0.0 5
 clock rate 64000

R5

interface Serial1/0
 ip address 155.1.0.5 255.255.255.0
 ip authentication mode eigrp 100 md5
 ip authentication key-chain eigrp 100 KEY_ROTATION
 no ip split-horizon eigrp 100
 encapsulation frame-relay
 serial restart-delay 0
 clock rate 2016000
 cdp enable
 frame-relay map ip 155.1.0.4 504 broadcast
 frame-relay map ip 155.1.0.3 503 broadcast
 frame-relay map ip 155.1.0.2 502 broadcast
 frame-relay map ip 155.1.0.1 501 broadcast
 no frame-relay inverse-arp
!

interface Serial1/1
 ip address 155.1.45.5 255.255.255.0
 serial restart-delay 0
 clock rate 64000

R5x#sh ip route | i 30\.|31\.
      30.0.0.0/8 is variably subnetted, 5 subnets, 2 masks
D        30.0.0.0/14 [90/2172416] via 155.1.0.4, 00:09:59, Serial1/0
D EX     30.0.0.0/16 [170/2172416] via 155.1.45.4, 00:06:58, Serial1/1
D EX     30.1.0.0/16 [170/2172416] via 155.1.45.4, 00:06:58, Serial1/1
D EX     30.2.0.0/16 [170/2172416] via 155.1.45.4, 00:06:58, Serial1/1
D EX     30.3.0.0/16 [170/2172416] via 155.1.45.4, 00:06:58, Serial1/1
      31.0.0.0/8 is variably subnetted, 5 subnets, 2 masks
D        31.0.0.0/14 [90/2172416] via 155.1.45.4, 00:06:58, Serial1/1
D EX     31.0.0.0/16 [170/2172416] via 155.1.0.4, 00:09:59, Serial1/0
D EX     31.1.0.0/16 [170/2172416] via 155.1.0.4, 00:09:59, Serial1/0
D EX     31.2.0.0/16 [170/2172416] via 155.1.0.4, 00:09:59, Serial1/0
D EX     31.3.0.0/16 [170/2172416] via 155.1.0.4, 00:09:59, Serial1/0

It is clear why the summaries are being advertised over different paths.

But why are the small subnets /16 also being advertised over different paths?

The metrics seem to be the same:

R5x#sh ip route 31.3.0.0
Routing entry for 31.3.0.0/16
  Known via "eigrp 100", distance 170, metric 2172416, type external
  Redistributing via eigrp 100
  Last update from 155.1.0.4 on Serial1/0, 00:10:44 ago
  Routing Descriptor Blocks:
  * 155.1.0.4, from 155.1.0.4, 00:10:44 ago, via Serial1/0
      Route metric is 2172416, traffic share count is 1
      Total delay is 20100 microseconds, minimum bandwidth is 1544 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 1
R5x#
R5x#
R5x#
R5x#sh ip route 30.3.0.0
Routing entry for 30.3.0.0/16
  Known via "eigrp 100", distance 170, metric 2172416, type external
  Redistributing via eigrp 100
  Last update from 155.1.45.4 on Serial1/1, 00:07:53 ago
  Routing Descriptor Blocks:
  * 155.1.45.4, from 155.1.45.4, 00:07:53 ago, via Serial1/1
      Route metric is 2172416, traffic share count is 1
      Total delay is 20100 microseconds, minimum bandwidth is 1544 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 1

Regards,

Mihai