What is Distribution-List ? How to configure?

Distribution lists

A distribution-list is used to control routing update either coming to your router or leaving from the router. Distribution-lists work on a variety of different IOS routing protocols like EIGRP, RIP, and OSPF. Distribution-list is one of the easiest ways to control routing updates, you can permit or deny routes using access-list or prefix-list or route map. Distribution-list can be applied to transmitted, received, or redistribute routing updates.

Each interface and routing process, Cisco IOS permits the following:

• One incoming global distribute list
• One outgoing global distribute list
• One incoming interface distribute list
• One outgoing interface distribute list
• One outgoing redistribution distribute list

configuration:

Topology 

Goal:

• configure topology as per our diagram and configure EIGRP 100
• advertise all the interfaces in EIGRP 
• configure router 3 deny 13.0.0.0/24 and 13.0.1.0/24 networks from being advertised to router 2 using distribution lists.

R1#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        10.1.1.1        YES manual up                    up

Serial3/0                    1.1.1.1         YES manual up                    up

Loopback0              11.0.0.1        YES manual up                    up

Loopback1              11.0.1.1        YES manual up                    up

Loopback2              11.0.2.1        YES manual up                    up

Loopback3              11.0.3.1        YES manual up                    up

R2#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        20.1.1.1        YES manual up                    up

Serial3/0                     1.1.1.2         YES manual up                    up

Serial3/1                      2.2.2.1         YES manual up                    up

Loopback0              12.0.0.1        YES manual up                    up

Loopback1              12.0.1.1        YES manual up                    up

Loopback2              12.0.2.1        YES manual up                    up

Loopback3              12.0.3.1        YES manual up                    up

R3#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        30.1.1.1        YES manual up                    up

Serial3/1                    2.2.2.2         YES manual up                    up

Loopback0              13.0.0.1        YES manual up                    up

Loopback1              13.0.1.1        YES manual up                    up

Loopback2              13.0.2.1        YES manual up                    up

Loopback3              13.0.3.1        YES manual up                    up

R1(config)#router eigrp 100

R1(config-router)#network 1.0.0.0

R1(config-router)#network 10.0.0.0

R1(config-router)#network 11.0.0.0

R1(config-router)#no auto-summary

R1(config-router)#end

R2(config)#router eigrp 100

R2(config-router)#network 1.0.0.0

R2(config-router)#network 2.0.0.0

R2(config-router)#network 20.0.0.0

R2(config-router)#network 12.0.0.0

R2(config-router)#no auto-summary

 R3(config)#router eigrp 100

R3(config-router)#network 2.0.0.0

R3(config-router)#network 30.0.0.0

R3(config-router)#network 13.0.0.0

R3(config-router)#no auto-summary

R3(config-router)#end

R1#show ip route eigrp

Codes: L - local, 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, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

D     2.0.0.0/8 [90/2681856] via 1.1.1.2, 00:35:31, Serial3/0

      12.0.0.0/24 is subnetted, 4 subnets

D        12.0.0.0 [90/2297856] via 1.1.1.2, 00:49:36, Serial3/0

D        12.0.1.0 [90/2297856] via 1.1.1.2, 00:49:36, Serial3/0

D        12.0.2.0 [90/2297856] via 1.1.1.2, 00:49:36, Serial3/0

D        12.0.3.0 [90/2297856] via 1.1.1.2, 00:49:36, Serial3/0

      13.0.0.0/24 is subnetted, 4 subnets

D        13.0.0.0 [90/2809856] via 1.1.1.2, 00:35:31, Serial3/0

D        13.0.1.0 [90/2809856] via 1.1.1.2, 00:35:31, Serial3/0

D        13.0.2.0 [90/2809856] via 1.1.1.2, 00:35:31, Serial3/0

D        13.0.3.0 [90/2809856] via 1.1.1.2, 00:35:31, Serial3/0

D     20.0.0.0/8 [90/2172416] via 1.1.1.2, 00:49:42, Serial3/0

D     30.0.0.0/8 [90/2684416] via 1.1.1.2, 00:35:31, Serial3/0

R2#show ip route eigrp

Codes: L - local, 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, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

D     10.0.0.0/8 [90/2172416] via 1.1.1.1, 00:39:25, Serial3/0

      11.0.0.0/24 is subnetted, 4 subnets

D        11.0.0.0 [90/2297856] via 1.1.1.1, 00:39:25, Serial3/0

D        11.0.1.0 [90/2297856] via 1.1.1.1, 00:39:25, Serial3/0

D        11.0.2.0 [90/2297856] via 1.1.1.1, 00:39:25, Serial3/0

D        11.0.3.0 [90/2297856] via 1.1.1.1, 00:39:25, Serial3/0

      13.0.0.0/24 is subnetted, 4 subnets

D        13.0.0.0 [90/2297856] via 2.2.2.2, 00:36:01, Serial3/1

D        13.0.1.0 [90/2297856] via 2.2.2.2, 00:36:01, Serial3/1

D        13.0.2.0 [90/2297856] via 2.2.2.2, 00:36:01, Serial3/1

D        13.0.3.0 [90/2297856] via 2.2.2.2, 00:36:01, Serial3/1

D     30.0.0.0/8 [90/2172416] via 2.2.2.2, 00:36:01, Serial3/1

R3#show ip route eigrp

Codes: L - local, 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, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

D     1.0.0.0/8 [90/2681856] via 2.2.2.1, 00:36:22, Serial3/1

D     10.0.0.0/8 [90/2684416] via 2.2.2.1, 00:36:22, Serial3/1

      11.0.0.0/24 is subnetted, 4 subnets

D        11.0.0.0 [90/2809856] via 2.2.2.1, 00:36:22, Serial3/1

D        11.0.1.0 [90/2809856] via 2.2.2.1, 00:36:22, Serial3/1

D        11.0.2.0 [90/2809856] via 2.2.2.1, 00:36:22, Serial3/1

D        11.0.3.0 [90/2809856] via 2.2.2.1, 00:36:22, Serial3/1

      12.0.0.0/24 is subnetted, 4 subnets

D        12.0.0.0 [90/2297856] via 2.2.2.1, 00:36:22, Serial3/1

D        12.0.1.0 [90/2297856] via 2.2.2.1, 00:36:22, Serial3/1

D        12.0.2.0 [90/2297856] via 2.2.2.1, 00:36:22, Serial3/1

D        12.0.3.0 [90/2297856] via 2.2.2.1, 00:36:22, Serial3/1

D     20.0.0.0/8 [90/2172416] via 2.2.2.1, 00:36:22, Serial3/1

R3(config)#access-list 10 deny 13.0.0.0 0.0.0.255

R3(config)#access-list 10 deny 13.0.1.0 0.0.0.255

R3(config)#access-list 10 permit any

R3(config)#router eigrp 100

R3(config-router)#distribute-list 10 out serial 3/1

R2#sh ip route eigrp

Codes: L - local, 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, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

D     10.0.0.0/8 [90/2172416] via 1.1.1.1, 00:00:12, Serial3/0

      11.0.0.0/24 is subnetted, 4 subnets

D        11.0.0.0 [90/2297856] via 1.1.1.1, 00:00:12, Serial3/0

D        11.0.1.0 [90/2297856] via 1.1.1.1, 00:00:12, Serial3/0

D        11.0.2.0 [90/2297856] via 1.1.1.1, 00:00:12, Serial3/0

D        11.0.3.0 [90/2297856] via 1.1.1.1, 00:00:12, Serial3/0

      13.0.0.0/24 is subnetted, 2 subnets

D        13.0.2.0 [90/2297856] via 2.2.2.2, 00:00:12, Serial3/1

D        13.0.3.0 [90/2297856] via 2.2.2.2, 00:00:12, Serial3/1

D     30.0.0.0/8 [90/2172416] via 2.2.2.2, 00:00:12, Serial3/1

from the above output you can see there is no 13.0.0.1 and 13.0.1.1 route coming from router 3.

R3#show ip protocols

*** IP Routing is NSF aware ***

Routing Protocol is "eigrp 100"

  Outgoing update filter list for all interfaces is not set

    Serial3/1 filtered by 10 (per-user), default is not set

  Incoming update filter list for all interfaces is not set

  Default networks flagged in outgoing updates

  Default networks accepted from incoming updates

  EIGRP-IPv4 Protocol for AS(100)

    Metric weight K1=1, K2=0, K3=1, K4=0, K5=0

    NSF-aware route hold timer is 240

    Router-ID: 30.1.1.1

    Topology : 0 (base)

      Active Timer: 3 min

      Distance: internal 90 external 170

      Maximum path: 4

      Maximum hop count 100

      Maximum metric variance 1

  Automatic Summarization: disabled

  Maximum path: 4

  Routing for Networks:

    2.0.0.0

    13.0.0.0

    30.0.0.0

  Routing Information Sources:

    Gateway         Distance      Last Update

    2.2.2.1               90      00:07:04

  Distance: internal 90 external 170