EIGRP network statement

_maurice_maurice Member Posts: 142
in CCNP
Under the EIGRP routing process, when you issue the command "network 10.0.0.0", but the actual interface has a 24-bit mask, what will be put into the route table: the Class A network or the class C network?

Does OSPF give you the *option* to leave the mask out of the command?

Thank you!
· Share on FacebookShare on Twitter

Comments

  • _maurice_maurice Member Posts: 142
    Oh wait, the network command just catches interfaces with those subnets, huh? So with no mask on the network command, does it assume a classful mask?
    · Share on FacebookShare on Twitter
  • tech-airmantech-airman Member Posts: 953
    _maurice wrote:
    Under the EIGRP routing process, when you issue the command "network 10.0.0.0", but the actual interface has a 24-bit mask, what will be put into the route table: the Class A network or the class C network?

    Does OSPF give you the *option* to leave the mask out of the command?

    Thank you!

    _maurice,

    For your EIGRP question it depends. Did you configure no auto-summary?

    For your OSPF question, no you do not have the option to leave the wildcard mask out for OSPF because by default and always, OSPF is a pure classless routing protocol therefore VLSM is required with no mechanism for automatic summarization but you can manually summarize on approximations of classful boundaries.

    I hope this helps.
    · Share on FacebookShare on Twitter
  • _maurice_maurice Member Posts: 142
    Yes, no auto is configured
    · Share on FacebookShare on Twitter
  • cisco_troopercisco_trooper Member Posts: 1,441 ■■■■□□□□□□
    Why don't you lab it up man? It's just a couple configuration lines...

    Tell us what you come up with and why you think it is that way.

    This is my favorite way to learn. :D
    · Share on FacebookShare on Twitter
  • _maurice_maurice Member Posts: 142
    lol, I'm at work, i cant lab it up
    · Share on FacebookShare on Twitter
  • dynamikdynamik Banned Posts: 12,312 ■■■■■■■■■□
    You can't SSH to your home lab? What do you do all day?
    · Share on FacebookShare on Twitter
  • cisco_troopercisco_trooper Member Posts: 1,441 ■■■■□□□□□□
    Need I say it: dynamips


    There, I said it.
    · Share on FacebookShare on Twitter
  • tech-airmantech-airman Member Posts: 953
    _maurice wrote:
    Yes, no auto is configured

    _maurice,

    When you mention the "route table" are you talking about the IP-EIGRP Routing Table or the router's routing table?
    · Share on FacebookShare on Twitter
  • _maurice_maurice Member Posts: 142
    I probably mean the IP-EIGRP routing table, as connected routes will show in the router's route table since it has a lower AD than EIGRP's 90 AD. Right?
    · Share on FacebookShare on Twitter
  • tech-airmantech-airman Member Posts: 953
    _maurice wrote:
    I probably mean the IP-EIGRP routing table, as connected routes will show in the router's route table since it has a lower AD than EIGRP's 90 AD. Right?

    _maurice,

    Let's first deal with the first question first, ok? As far as the network 10.0.0.0 under no auto-summary conditions, the EIGRP routing protocol goes from classful to classless status. Since it is now classless, your original question of "...what will be put into the route table: the Class A network or the class C network?" becomes a moot question because once you go classless, Class A/B/C no longer apply. However, it's still an interesting question of what route will be installed into the router's routing table so that's why I'll keep going. So the network that should show up in the IP-EIGRP Topology table should be "10.0.0.0/24." So this leads to the next question, is EIGRP the only dynamic routing protocol configured on the router?
    · Share on FacebookShare on Twitter
  • kryollakryolla Member Posts: 785
    the network command has nothing to do with the subnet mask of the interface. All it does is tell the process what interface to run the protocol.
    Studying for CCIE and drinking Home Brew
    · Share on FacebookShare on Twitter
  • cisco_troopercisco_trooper Member Posts: 1,441 ■■■■□□□□□□
    kryolla wrote:
    the network command has nothing to do with the subnet mask of the interface. All it does is tell the process what interface to run the protocol.

    I would agree. The network statement is simply a pattern matching tool to tell EIGRP to run on an interface.
    · Share on FacebookShare on Twitter
  • _maurice_maurice Member Posts: 142
    In the absence of the optional subnet mask in the network command for EIGRP, will it match based on classful rules?

    network 10.0.0.0 = interfaces with IPs in the range of 10.0.0.0 - 10.255.255.255
    network 180.0.0.0 = interfaces with IPs in the range of 180.0.0.0 - 180.0.255.255
    network 200.0.0.0 = interfaces with IPs in the range of 200.0.0.0 - 200.0.0.255
    · Share on FacebookShare on Twitter
  • kryollakryolla Member Posts: 785
    _maurice wrote:
    In the absence of the optional subnet mask in the network command for EIGRP, will it match based on classful rules?

    network 10.0.0.0 = interfaces with IPs in the range of 10.0.0.0 - 10.255.255.255
    network 180.0.0.0 = interfaces with IPs in the range of 180.0.0.0 - 180.0.255.255
    network 200.0.0.0 = interfaces with IPs in the range of 200.0.0.0 - 200.0.0.255

    yes
    Studying for CCIE and drinking Home Brew
    · Share on FacebookShare on Twitter
  • tech-airmantech-airman Member Posts: 953
    _maurice wrote:
    In the absence of the optional subnet mask in the network command for EIGRP, will it match based on classful rules?

    network 10.0.0.0 = interfaces with IPs in the range of 10.0.0.0 - 10.255.255.255
    network 180.0.0.0 = interfaces with IPs in the range of 180.0.0.0 - 180.0.255.255
    network 200.0.0.0 = interfaces with IPs in the range of 200.0.0.0 - 200.0.0.255

    _maurice,

    Is "no auto-summary" still configured?
    · Share on FacebookShare on Twitter
  • networker050184networker050184 Mod Posts: 11,962 Mod
    tech-airman wrote:
    _maurice wrote:
    In the absence of the optional subnet mask in the network command for EIGRP, will it match based on classful rules?

    network 10.0.0.0 = interfaces with IPs in the range of 10.0.0.0 - 10.255.255.255
    network 180.0.0.0 = interfaces with IPs in the range of 180.0.0.0 - 180.0.255.255
    network 200.0.0.0 = interfaces with IPs in the range of 200.0.0.0 - 200.0.0.255

    _maurice,

    Is "no auto-summary" still configured?

    That has nothing to do with what interfaces it will include.
    An expert is a man who has made all the mistakes which can be made.
    · Share on FacebookShare on Twitter
  • kryollakryolla Member Posts: 785
    The auto summary is for when a route crosses a network boundary and whether the router makes it classful or not. It has nothing to do with the directly connected interfaces and the way it is put in the routing table
    Studying for CCIE and drinking Home Brew
    · Share on FacebookShare on Twitter
  • tech-airmantech-airman Member Posts: 953
    networker050184 wrote:
    tech-airman wrote:
    _maurice wrote:
    In the absence of the optional subnet mask in the network command for EIGRP, will it match based on classful rules?

    network 10.0.0.0 = interfaces with IPs in the range of 10.0.0.0 - 10.255.255.255
    network 180.0.0.0 = interfaces with IPs in the range of 180.0.0.0 - 180.0.255.255
    network 200.0.0.0 = interfaces with IPs in the range of 200.0.0.0 - 200.0.0.255

    _maurice,

    Is "no auto-summary" still configured?

    That has nothing to do with what interfaces it will include.

    networker050184,

    Actually it does. I labbed it up and here's the topology diagram.
                (R2)
              |
(R1)-----[switch]----(R3)

    Here's my configurations and outputs.
    R1

Router>en
Router#config t
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#line con 0
Router(config-line)#logging synchronous
Router(config-line)#exit
Router(config)#hostname R1
R1(config)#interface fastethernet 0/0
R1(config-if)#ip address 10.0.0.1 255.255.255.0
R1(config-if)#exit
R1(config)#exit
R1#
*Sep 18 00:47:40.031: %SYS-5-CONFIG_I: Configured from console by console
R1#config t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#router eigrp 1
R1(config-router)#network 10.0.0.0
R1(config-router)#exit
R1(config)#exit
R1#
*Sep 18 00:49:28.871: %SYS-5-CONFIG_I: Configured from console by console
R1#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

R1#show ip route eigrp

R1#show ip eigrp neighbors
IP-EIGRP neighbors for process 1
R1#show ip eigrp topology
IP-EIGRP Topology Table for AS(1)/ID(10.0.0.1)
R1#show ip route eigrp

R1#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

R1#

    R2

Router>en
Router#config t
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#line con 0
Router(config-line)#logging synchronous
Router(config-line)#exit
Router(config)#hostname R2
R2(config)#interface fastethernet 0/0
R2(config-if)#ip address 10.0.0.2 255.255.255.0
R2(config-if)#no shutdown
R2(config-if)#exit
R2(config)#e
*Sep 18 00:48:05.811: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state t
o up
*Sep 18 00:48:06.811: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthern
et0/0, changed state to up
R2(config)#exit
R2#
*Sep 18 00:48:08.195: %SYS-5-CONFIG_I: Configured from console by console
R2#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

     10.0.0.0/24 is subnetted, 1 subnets
C       10.0.0.0 is directly connected, FastEthernet0/0
R2#config t
Enter configuration commands, one per line.  End with CNTL/Z.
R2(config)#router eigrp 1
R2(config-router)#no auto-summary
R2(config-router)#network 10.0.0.0
R2(config-router)#exit
R2(config)#
*Sep 18 00:50:50.727: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 10.0.0.3 (FastE
thernet0/0) is up: new adjacency
R2(config)#exit
R2#
*Sep 18 00:50:53.403: %SYS-5-CONFIG_I: Configured from console by console
R2#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

     10.0.0.0/24 is subnetted, 1 subnets
C       10.0.0.0 is directly connected, FastEthernet0/0
R2#show ip route eigrp

R2#show ip eigrp neighbors
IP-EIGRP neighbors for process 1
H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
                                            (sec)         (ms)       Cnt Num
0   10.0.0.3                Fa0/0             14 00:02:01 1276  5000  0  3
R2#show ip eigrp topology
IP-EIGRP Topology Table for AS(1)/ID(10.0.0.2)

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

P 10.0.0.0/24, 1 successors, FD is 28160
        via Connected, FastEthernet0/0
R2#show ip route eigrp

R2#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

     10.0.0.0/24 is subnetted, 1 subnets
C       10.0.0.0 is directly connected, FastEthernet0/0
R2#

    R3

Router>en
Router#config t
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#line con 0
Router(config-line)#logging synchronous
Router(config-line)#exit
Router(config)#hostname R3
R3(config)#interface fastethernet 0/0
R3(config-if)#ip address 10.0.0.3 255.255.255.0
R3(config-if)#no shutdown
R3(config-if)#exit
R3(config)#exit
R3#
*Sep 18 00:51:54.179: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state t
o up
R3#
*Sep 18 00:51:54.515: %SYS-5-CONFIG_I: Configured from console by console
*Sep 18 00:51:55.179: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthern
et0/0, changed state to up
R3#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

     10.0.0.0/24 is subnetted, 1 subnets
C       10.0.0.0 is directly connected, FastEthernet0/0
R3#config t
Enter configuration commands, one per line.  End with CNTL/Z.
R3(config)#router eigrp 1
R3(config-router)#no auto-summary
R3(config-router)#network 10.0.0.0 255.255.255.0
R3(config-router)#exit
R3(config)#exit
R3#
*Sep 18 00:54:09.703: %SYS-5-CONFIG_I: Configured from console by console
R3#
*Sep 18 00:54:14.911: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 10.0.0.2 (FastE
thernet0/0) is up: new adjacency
R3#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

     10.0.0.0/24 is subnetted, 1 subnets
C       10.0.0.0 is directly connected, FastEthernet0/0
R3#show ip route eigrp

R3#show ip eigrp neighbors
IP-EIGRP neighbors for process 1
H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
                                            (sec)         (ms)       Cnt Num
0   10.0.0.2                Fa0/0             13 00:02:29    9   200  0  3
R3#show ip eigrp topology
IP-EIGRP Topology Table for AS(1)/ID(10.0.0.3)

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

P 10.0.0.0/24, 1 successors, FD is 28160
        via Connected, FastEthernet0/0
R3#show ip route eigrp

R3#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

     10.0.0.0/24 is subnetted, 1 subnets
C       10.0.0.0 is directly connected, FastEthernet0/0
R3#

    So in summary:
    1. On R1, I typed the following
      [list=1:38b304bcb8]
    2. network 10.0.0.0
    [*]On R2, I typed the following
    1. no auto-summary
    2. network 10.0.0.0
    [*]On R3, I typed the following
    1. no auto-summary
    2. network 10.0.0.0 255.255.255.0
    [/list:o:38b304bcb8]

    Therefore, based on the outputs on R1, failure to configure "no auto-summary" made R1 fail to even form a neighbor relationship with R2 or R3 as well as R1 having an empty IP-EIGRP Routing table and an empty router routing table.
    · Share on FacebookShare on Twitter
  • tech-airmantech-airman Member Posts: 953
    kryolla wrote:
    The auto summary is for when a route crosses a network boundary and whether the router makes it classful or not. It has nothing to do with the directly connected interfaces and the way it is put in the routing table

    kryolla,

    See above.
    · Share on FacebookShare on Twitter
  • kryollakryolla Member Posts: 785
    actually you wont have any eigrp routes in the RIB due to no remote routes all the routes are directly connected. As far as I know you should have directly connected route in R1 did you do a sh ip eigrp int to see if int fa0/0 is indeed part of EIGRP process. The auto summary has nothing to do with adjacencies forming or the way directly connected routes are put in the RIB. It is when one interface is configured with a different network boundary than the other will it matter.

    After looking at your config again you forgot no shut on R1 that is why it is not showing up. :)
    Studying for CCIE and drinking Home Brew
    · Share on FacebookShare on Twitter
  • tech-airmantech-airman Member Posts: 953
    kryolla wrote:
    actually you wont have any eigrp routes in the RIB due to no remote routes all the routes are directly connected. As far as I know you should have directly connected route in R1 did you do a sh ip eigrp int to see if int fa0/0 is indeed part of EIGRP process. The auto summary has nothing to do with adjacencies forming or the way directly connected routes are put in the RIB. It is when one interface is configured with a different network boundary than the other will it matter.

    After looking at your config again you forgot no shut on R1 that is why it is not showing up. :)

    *doh* You're right. :D Lemme see if that might fix things.
    · Share on FacebookShare on Twitter
  • _maurice_maurice Member Posts: 142
    Thanks guys for being so cool! I labbed it up with dynamips when I got home, and EIGRP's network command now makes sense to me!

    Thank you!
    · Share on FacebookShare on Twitter
  • tech-airmantech-airman Member Posts: 953
    kryolla wrote:
    actually you wont have any eigrp routes in the RIB due to no remote routes all the routes are directly connected. As far as I know you should have directly connected route in R1 did you do a sh ip eigrp int to see if int fa0/0 is indeed part of EIGRP process. The auto summary has nothing to do with adjacencies forming or the way directly connected routes are put in the RIB. It is when one interface is configured with a different network boundary than the other will it matter.

    After looking at your config again you forgot no shut on R1 that is why it is not showing up. :)

    So here's the additional outputs after correcting that error...
    R1

R1#config t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#interface fastethernet 0/0
R1(config-if)#no shutdown
R1(config-if)#exit
R1(config)#exit
R1#
*Sep 18 02:47:23.035: %SYS-5-CONFIG_I: Configured from console by console
R1#
*Sep 18 02:47:23.099: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state t
o up
*Sep 18 02:47:24.099: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthern
et0/0, changed state to up
R1#show ip eigrp neighbors
IP-EIGRP neighbors for process 1
R1#show ip eigrp topology
IP-EIGRP Topology Table for AS(1)/ID(10.0.0.1)

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

P 10.0.0.0/24, 1 successors, FD is 28160
        via Connected, FastEthernet0/0
R1#show ip eigrp
*Sep 18 02:47:56.075: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 10.0.0.2 (FastE
thernet0/0) is up: new adjacency
*Sep 18 02:47:56.079: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 10.0.0.3 (FastE
thernet0/0) is up: new adjacency
R1#show ip route eigrp

R1#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

     10.0.0.0/24 is subnetted, 1 subnets
C       10.0.0.0 is directly connected, FastEthernet0/0
R1#show ip eigrp int
R1#show ip eigrp interfaces
IP-EIGRP interfaces for process 1

                        Xmit Queue   Mean   Pacing Time   Multicast    Pending
Interface        Peers  Un/Reliable  SRTT   Un/Reliable   Flow Timer   Routes
Fa0/0              2        0/0       639       0/1           50           0
R1#
    · Share on FacebookShare on Twitter
Sign In or Register to comment.