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Helpful
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Replies

OSPF help

Hello everyone,

So, I'm having issues with OSPF. I had it working, but after I logged out of the packet tracer, it decided it did not work anymore. It keeps getting stuck in the exstart/dr state. I don't know if this could be a packet tracer issue or if I'm missing something important; however, it was working the night before, and I did save it, but now I don't have communication between the multilayer switch and the router.

Neighbor ID Pri State Dead Time Address Interface
10.210.61.1 1 EXSTART/DR 00:00:38 10.210.61.2 GigabitEthernet0/0

 

Here is my config for my router

 

Building configuration...




Current configuration : 1400 bytes

!

version 15.1

no service timestamps log datetime msec

no service timestamps debug datetime msec

service password xxx

!

hostname Router

!

!

!

enable secret xxx

!

!

!

!

!

aaa new-model

!

aaa authentication login default local group tacacs+

!

!

!

!

!

!

!

ip cef

no ipv6 cef

!

!

!

username testuser secret xxx

!

!

license udi pid CISCO1941/K9 sn xxx

!

!

!

!

!

!

!

!

!

!

!

spanning-tree mode pvst

!

!

!

!

!

!

interface GigabitEthernet0/0

ip address 10.210.61.1 255.255.255.192

ip ospf 1 area 0

duplex auto

speed auto

!

interface GigabitEthernet0/1

no ip address

duplex auto

speed auto

!

interface GigabitEthernet0/1.10

encapsulation dot1Q 10

no ip address

shutdown

!

interface Vlan1

no ip address

shutdown

!

router ospf 1

router-id 10.210.61.1

log-adjacency-changes

network 10.210.61.192 0.0.0.63 area 0

network 10.210.61.128 0.0.0.63 area 0

network 10.210.61.64 0.0.0.63 area 0

!

ip classless




config for multi-layer switch 




no service timestamps log datetime msec

no service timestamps debug datetime msec

no service password xxx

!

hostname Switch

!

!

!

!

ip dhcp pool vlan10

network 10.210.61.64 255.255.255.192

default-router 10.210.61.65

ip dhcp pool vlan20

network 10.210.61.128 255.255.255.192

default-router 10.210.61.129

ip dhcp pool vlan30

network 10.210.61.192 255.255.255.192

default-router 10.210.61.193

!

!

!

no ip cef

ip routing

!

no ipv6 cef

!

!

!

!

!

!

!

!

!

!

!

!

!

!

spanning-tree mode pvst

!

!

!

!

!

!

interface GigabitEthernet1/0/1

switchport mode trunk

!

interface GigabitEthernet1/0/2

switchport mode trunk

!

interface GigabitEthernet1/0/3

no switchport

ip address 10.210.61.2 255.255.255.192

ip ospf 1 area 0

duplex auto

speed auto

!

interface GigabitEthernet1/0/4

!

interface GigabitEthernet1/0/5

!

interface GigabitEthernet1/0/6

!

interface GigabitEthernet1/0/7

!

interface GigabitEthernet1/0/8

!

interface GigabitEthernet1/0/9

!

interface GigabitEthernet1/0/10

!

interface GigabitEthernet1/0/11

!

interface GigabitEthernet1/0/12

!

interface GigabitEthernet1/0/13

!

interface GigabitEthernet1/0/14

!

interface GigabitEthernet1/0/15

!

interface GigabitEthernet1/0/16

!

interface GigabitEthernet1/0/17

!

interface GigabitEthernet1/0/18

!

interface GigabitEthernet1/0/19

!

interface GigabitEthernet1/0/20

!

interface GigabitEthernet1/0/21

!

interface GigabitEthernet1/0/22

!

interface GigabitEthernet1/0/23

!

interface GigabitEthernet1/0/24

!

interface GigabitEthernet1/1/1

!

interface GigabitEthernet1/1/2

!

interface GigabitEthernet1/1/3

!

interface GigabitEthernet1/1/4

!

interface Vlan1

no ip address

shutdown

!

interface Vlan10

mac-address 00d0.5885.2301

ip address 10.210.61.65 255.255.255.192

!

interface Vlan20

mac-address 00d0.5885.2302

ip address 10.210.61.129 255.255.255.192

!

interface Vlan30

mac-address 00d0.5885.2303

ip address 10.210.61.193 255.255.255.192

!

router ospf 1

router-id 10.210.61.1

log-adjacency-changes

network 10.210.61.192 0.0.0.63 area 0

network 10.210.61.128 0.0.0.63 area 0

network 10.210.61.64 0.0.0.63 area 0

!

ip classless

!

ip flow-export version 9

!

 

3 Accepted Solutions

Accepted Solutions

M02@rt37
VIP
VIP

Hello @BoomBastic1234626283,

On you multi layer Switch modify the

router-id

on the OSPF process. Router and this Sw has got the same

router-id.

Instead of 

router-id 10.210.61.1

Configure this: 

router-id 10.210.61.2

 

Best regards
.ı|ı.ı|ı. If This Helps, Please Rate .ı|ı.ı|ı.

View solution in original post

Blue_Bird
VIP
VIP

That's it...both router and Multilayer switch are having same

router-id: 10.210.61.1
router-id

is unique...two devices should not have the same

router-id

. Chage

router-id

in any one of the device (router or Multi-laryer switch)

that solve's the problem....

Thanks

View solution in original post

Joseph W. Doherty
Hall of Fame
Hall of Fame

Glad to read your problem was identified.

If you're learning networking, I have several suggestions.

Change default pvst to rapid pvst.

Change link between switch and router to /30 or /31.  For OSPF, configure it as

p2p.  (/30 or /31 not required for OSPF p2p.)

Don't use an interface IP for RID unless it's a loopback. If you use loopback for RID consider adding it to OSPF.

Using the (newer) interface OSPF statement negates the need to use an OSPF network statement to pick up interface's IP network; believe you could use it on your SVIs.

Your router doesn't need subinterfaces nor VLAN OSPF network statements.

OSPF network statements do not advertise networks, they pick up matching interface IP addresses for interface's IP network inclusion.  I.e. they work like an ACL ACE matching interface IP.

For example for:

ip address 10.210.61.65 255.255.255.192

Besides

network 10.210.61.64 0.0.0.63 area 0

The following would also do the same:

network 10.210.61.65 0.0.0.0 area 0

(The prior is the equivalent of interface statement "ip ospf 1 area 0".)

network 10.210.61.0 0.0.0.255 area 0

network 0.0.0.0 255.255.255.255 area 0

The last two network statements, especially the last, might match multiple interfaces.  Either of those would match all your interfaces on your switch.

View solution in original post

6 Replies 6

M02@rt37
VIP
VIP

Hello @BoomBastic1234626283,

On you multi layer Switch modify the

router-id

on the OSPF process. Router and this Sw has got the same

router-id.

Instead of 

router-id 10.210.61.1

Configure this: 

router-id 10.210.61.2

 

Best regards
.ı|ı.ı|ı. If This Helps, Please Rate .ı|ı.ı|ı.

Blue_Bird
VIP
VIP

That's it...both router and Multilayer switch are having same

router-id: 10.210.61.1
router-id

is unique...two devices should not have the same

router-id

. Chage

router-id

in any one of the device (router or Multi-laryer switch)

that solve's the problem....

Thanks

Hello,

post the (zipped) Packet Tracer project

(.pkt) file...

Joseph W. Doherty
Hall of Fame
Hall of Fame

Glad to read your problem was identified.

If you're learning networking, I have several suggestions.

Change default pvst to rapid pvst.

Change link between switch and router to /30 or /31.  For OSPF, configure it as

p2p.  (/30 or /31 not required for OSPF p2p.)

Don't use an interface IP for RID unless it's a loopback. If you use loopback for RID consider adding it to OSPF.

Using the (newer) interface OSPF statement negates the need to use an OSPF network statement to pick up interface's IP network; believe you could use it on your SVIs.

Your router doesn't need subinterfaces nor VLAN OSPF network statements.

OSPF network statements do not advertise networks, they pick up matching interface IP addresses for interface's IP network inclusion.  I.e. they work like an ACL ACE matching interface IP.

For example for:

ip address 10.210.61.65 255.255.255.192

Besides

network 10.210.61.64 0.0.0.63 area 0

The following would also do the same:

network 10.210.61.65 0.0.0.0 area 0

(The prior is the equivalent of interface statement "ip ospf 1 area 0".)

network 10.210.61.0 0.0.0.255 area 0

network 0.0.0.0 255.255.255.255 area 0

The last two network statements, especially the last, might match multiple interfaces.  Either of those would match all your interfaces on your switch.

You use dhcp pool and ospf 

When you close one of l3 device have

router ID

and then when you open again the dhcp assign different IP make other devices have same IP and use same

router ID

. That what I think if I am right.

Clear

 ip ospf

process and check if it solve issue then it sure it

router ID 

issue

Huh?

Could you further explain how DHCP relates/influences the hard coded, same, OSPF RID (10.210.61.1) on both the router and L3 switch?

Perhaps you have mind the defined pools don't explicitly exclude gateway IP being used?

If you do, though, the adjacency issue is on a network without a DHCP pool.

So, cannot see a direct impact but it would be a good suggestion to mention explicitly excluding gateway IPs.

Another possibly good suggestion, which I intended to add in my prior reply, but then forgot, would be to make the SVIs passive interfaces.