secondary ip and eigrp

hi all,

cisco says that

“Routers do not form EIGRP neighbors over secondary networks.“

i configured a lab on gns3 and adjacency is working fine ??

can any one explain ??

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Comments

JHON CENA

HYG my topology

test.jpg

SteveO86

It's possible that was from an older config guide. I haven't labbed this in a while.

Can you post the following from both routers
sh ip eigrp nei
&
sh run int e0/0

late_collision

JHON CENA wrote: »

can any one explain ??

Consider for a moment what the eigrp network command does, it will enable the exchange of eigrp hello packets for an interface. By default the eigrp hello packets are exchanged via the 224.0.0.10 multicast address. Because of the multicast operation, neighbor adjacency is formed.

You can use the eigrp neighbor router command to disable exchanging of hello packets via the 224.0.0.10 multicast address and force unicast operation. When you do this, the adjacency will fail and you should received an error about different networks if you try to bind an eigrp neighbor on a network outside the interface primary ip network

JHON CENA

router 1
:::::::::::
R1#show running interface e0/0
Building configuration...

Current configuration : 114 bytes
!
interface Ethernet0/0
ip address 12.0.0.2 255.0.0.0 secondary
ip address 11.0.0.2 255.0.0.0
half-duplex
end

::::::::::::::::
R1#show ip eigrp neighbors
IP-EIGRP neighbors for process 1
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
0 12.0.0.3 Et0/0 13 00:15:04 12 200 0 2

::::::::::::::
router 2
:::::::::::::

R2#show running interface e0/0
Building configuration...

Current configuration : 114 bytes
!
interface Ethernet0/0
ip address 11.0.0.3 255.0.0.0 secondary
ip address 12.0.0.3 255.0.0.0
half-duplex
end

:::::::::::::::::::::::::

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 11.0.0.2 Et0/0 13 00:16:07 24 200 0 2

::::::::::::::

waiting you replay as cisco says it is not possible ...

EdTheLad

As per the below output, the secondary address is not used to form an adjacency, it is used to enable eigrp on an interface. Eigrp however will send the hello's using the primary ip address and hence the adjacency is formed using the primary address.

R1#sh runn int eth 0/0
Building configuration...

Current configuration : 145 bytes
!
interface Ethernet0/0
ip address 192.168.1.1 255.255.255.0 secondary
ip address 10.0.12.1 255.255.255.0
ip ospf network point-to-point
end

R1#sh runn | sec eigrp
router eigrp 1
network 192.168.1.0
R1#sh ip eigrp neigh
EIGRP-IPv4 Neighbors for AS(1)
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
0 10.0.12.2 Et0/0 10 00:03:20 10 100 0 1
R1#
R1#
R1#debug ip packet
IP packet debugging is on
R1#
*Mar 4 15:02:16.328: IP: s=10.0.12.2 (Ethernet0/0), d=224.0.0.10, len 60, rcvd 0
*Mar 4 15:02:16.328: IP: s=10.0.12.2 (Ethernet0/0), d=224.0.0.10, len 60, input feature, packet consumed, MCI Check(8

, rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE
*Mar 4 15:02:16.419: IP: s=10.0.12.2 (Ethernet0/0), d=224.0.0.5, len 80, rcvd 0
*Mar 4 15:02:16.419: IP: s=10.0.12.2 (Ethernet0/0), d=224.0.0.5, len 80, input feature, packet consumed, MCI Check(8

, rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE
*Mar 4 15:02:16.963: IP: s=10.0.12.1 (local), d=224.0.0.5 (Ethernet0/0), len 80, sending broad/multicast
R1#
*Mar 4 15:02:16.963: IP: s=10.0.12.1 (local), d=224.0.0.5 (Ethernet0/0), len 80, sending full packet
R1#
*Mar 4 15:02:18.373: IP: s=10.0.12.1 (local), d=224.0.0.10 (Ethernet0/0), len 60, sending broad/multicast
*Mar 4 15:02:18.373: IP: s=10.0.12.1 (local), d=224.0.0.10 (Ethernet0/0), len 60, sending full packet
R1#
*Mar 4 15:02:20.791: IP: s=10.0.13.3 (Ethernet0/1), d=224.0.0.5, len 80, rcvd 0
*Mar 4 15:02:20.791: IP: s=10.0.13.3 (Ethernet0/1), d=224.0.0.5, len 80, input feature, packet consumed, MCI Check(8

, rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE
*Mar 4 15:02:20.819: IP: s=10.0.12.2 (Ethernet0/0), d=224.0.0.10, len 60, rcvd 0
*Mar 4 15:02:20.819: IP: s=10.0.12.2 (Ethernet0/0), d=224.0.0.10, len 60, input feature, packet consumed, MCI Check(8

, rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE
*Mar 4 15:02:21.368: IP: s=10.0.13.1 (local), d=224.0.0.5 (Ethernet0/1), len 80, sending broad/multicast
R1#un all
*Mar 4 15:02:21.368: IP: s=10.0.13.1 (local), d=224.0.0.5 (Ethernet0/1), len 80, sending full packet
R1#un all
All possible debugging has been turned off
R1#
*Mar 4 15:02:22.825: IP: s=10.0.12.1 (local), d=224.0.0.10 (Ethernet0/0), len 60, sending broad/multicast
*Mar 4 15:02:22.825: IP: s=10.0.12.1 (local), d=224.0.0.10 (Ethernet0/0), len 60, sending full packet
R1#