Some Questions on OSPF 5

[Tony414]

Hello,
I am going to implement OSPF on our network. Not a big network, a total of only 5 1700 routers. Can anywone give me some common mistakes that people might make when implementing it? If there is evey any. Can someone give me a quick example? Lets just say I have 2 routers. Router A and Router B. One thing I'm not sure of is the area setting. Thanks in advance for the help.

Tony

 

[Tony414]

Also should each router be set to the same area?

 

[drewdown]

You enable it globally then you must assign interfaces to each area, or 1 area if thats all you are using. And no, each router doesn't have to be set to the same area. At my job I have them all in the same area, small office currently 5 devices participating in OSPF.

Cisco has lots of good information regarding OSPF

http://www.cisco.com/warp/public/104/1.html

 

[Tony414]

This is all that show up on Townhall after adding all those routes in all the routers

TownHall>sh ip ospf nei

Neighbor ID Pri State Dead Time Address Interface
172.16.51.2 0 FULL/ - 00:00:35 172.16.51.2 Serial0

 

[drewdown]

Is that the highschool router?

Can you post some configs from each showing the OSPF settings? Did you do what Burtbees posted?!

Turn on terminal monitoring and see if its getting updates from any other routers.

 

[burtsbees]

yeah---brain fart on the default-info-or...

Burt

 

[jneiberger]

They don't have to be in the same area but there is no point whatsoever in making this a multi-area network. It wouldn't matter much in this topology, but you lose some of the benefit of OSPF if you split your network into multiple areas. For future reference, and for a good trivia question among networking geeks like us, OSPF is a link state routing protocol within areas but it is a distance vector protocol between areas.

 

[burtsbees]

Myself, I would just use static routes, or EIGRP...

Burt

 

[jneiberger]

EIGRP is definitely a bit easier to setup, but it's a huge pain to advertise default routes. A combination of static defaults plus EIGRP would work great, though.

 

[Tony414]

Ok. Here is where I'm at. Seems to be working fine (the original problem I had with pinging is now working). But as soon I remove certain static routes things stop workin. In a perfect ospf world are static routes even needed? Here are a few configs. Townhall, Townhall2, Hichschool, and Publicworks

--------------------------------------------------------

version 12.3
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname TownHall
!
boot system flash flash:c1700-y-mz.123-1a.bin
enable password 7 14051D1E180138663020626771
!
ip subnet-zero
!
!
no ip domain lookup
!
!
!
!
!
interface FastEthernet0
description connected to TownHall LAN
ip address 10.81.0.1 255.255.0.0
speed 100
full-duplex
!
interface Serial0
description connected to HighSchool
ip address 172.16.51.1 255.255.255.252
no ip unreachables
encapsulation ppp
ip route-cache flow
service-module t1 clock source internal
service-module t1 remote-alarm-enable
service-module t1 fdl ansi
!
interface Serial1
description connected to PoliceDept
ip address 172.16.51.5 255.255.255.252
encapsulation ppp
ip route-cache flow
service-module t1 clock source internal
service-module t1 remote-alarm-enable
service-module t1 fdl ansi
!
router ospf 1
log-adjacency-changes
network 10.81.0.0 0.0.255.255 area 0
network 172.16.51.0 0.0.0.255 area 0
default-information originate always
!
ip classless
ip route 0.0.0.0 0.0.0.0 172.16.51.2 permanent
ip route 10.91.0.0 255.255.0.0 172.16.51.6 permanent
ip route 10.101.0.0 255.255.0.0 10.81.0.5 permanent
ip route 10.111.0.0 255.255.0.0 10.81.0.5 permanent
ip route 10.121.0.0 255.255.0.0 10.81.0.6 permanent
ip http server
------------------------------------------------------

version 12.3
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname TownHall2
!
boot system flash flash:c1700-y-mz.123-1a.bin
enable password 7 044904131B245E031D1157464058
!
ip subnet-zero
ip rcmd rsh-enable
ip rcmd remote-host tony414 10.81.0.16 tony414 enable
!
!
no ip domain lookup
!
!
!
!
!
interface FastEthernet0
description connected to TownHall LAN
ip address 10.81.0.5 255.255.0.0
speed 100
full-duplex
!
interface Serial0
description connected to PublicWorks
ip address 172.16.51.9 255.255.255.252
encapsulation ppp
no fair-queue
service-module t1 clock source internal
service-module t1 remote-alarm-enable
service-module t1 fdl ansi
!
interface Serial1
description connected to ParkRec
ip address 172.16.51.13 255.255.255.252
encapsulation ppp
service-module t1 clock source internal
service-module t1 remote-alarm-enable
service-module t1 fdl ansi
!
router ospf 1
log-adjacency-changes
network 10.81.0.0 0.0.255.255 area 0
network 172.16.51.0 0.0.0.255 area 0
!
ip classless
ip route 0.0.0.0 0.0.0.0 10.81.0.1 permanent
ip route 10.91.0.0 255.255.0.0 172.16.51.6 permanent
ip route 10.101.0.0 255.255.0.0 172.16.51.10 permanent
ip route 10.111.0.0 255.255.0.0 172.16.51.14 permanent
ip route 10.121.0.0 255.255.0.0 10.81.0.6 permanent
ip http server
-----------------------------------------------------

version 12.3
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname PublicWorks
!
boot system flash flash:c1700-y-mz.123-1a.bin
enable password 7 0316541E120A33015E1E485744
!
ip subnet-zero
no ip rcmd domain-lookup
!
!
!
!
!
!
!
interface FastEthernet0
description connected to PuplicWorks LAN
ip address 10.101.0.1 255.255.0.0
speed auto
!
interface Serial0
description connected to TownHall2
ip address 172.16.51.10 255.255.255.252
encapsulation ppp
no fair-queue
service-module t1 remote-alarm-enable
service-module t1 fdl ansi
!
router ospf 1
log-adjacency-changes
network 10.0.0.0 0.0.255.255 area 0
network 10.81.0.0 0.0.255.255 area 0
network 10.111.0.0 0.0.255.255 area 0
network 172.16.51.0 0.0.0.255 area 0
!
ip classless
ip route 0.0.0.0 0.0.0.0 172.16.51.9 permanent
ip http server
--------------------------------------------------------

version 12.2
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname HighSchool
!
enable password 7 06140034584B1B540D0443595F
!
ip subnet-zero
ip rcmd rsh-enable
ip rcmd remote-host tony414 10.81.0.16 tony414
no ip domain-lookup
!
!
!
!
interface FastEthernet0
description connected to HighSchool LAN
ip address 10.0.0.20 255.255.255.0
speed auto
!
interface Serial0
description connected to TownHall
ip address 172.16.51.2 255.255.255.252
encapsulation ppp
service-module t1 clock source internal
service-module t1 remote-alarm-enable
service-module t1 fdl ansi
!
router ospf 1
log-adjacency-changes
network 10.0.0.0 0.0.0.255 area 0
network 10.81.0.0 0.0.255.255 area 0
network 10.101.0.0 0.0.255.255 area 0
network 10.111.0.0 0.0.255.255 area 0
network 172.16.51.0 0.0.0.255 area 0
!
ip classless
ip route 0.0.0.0 0.0.0.0 10.0.0.1
ip route 10.81.0.0 255.255.0.0 172.16.51.1 permanent
ip route 10.91.0.0 255.255.0.0 172.16.51.1 permanent
ip route 10.101.0.0 255.255.0.0 172.16.51.1 permanent
ip route 10.111.0.0 255.255.0.0 172.16.51.1 permanent
ip route 10.121.0.0 255.255.0.0 172.16.51.1 permanent
ip http server

 

[jneiberger]

At first glance, you have two unnecessary network statements on PublicWorks and three on HighSchool. You should probably clean those up a bit. I look at the configs more closely after I'm done with dinner.

 

[Tony414]

Are you talking about the ospf routes, static routes or both? Dinner first...feed the fire

 

[Tony414]

Here are some show commands for ospf on few of routers...

TownHall>sh ip ospf nei

Neighbor ID Pri State Dead Time Address Interface
172.16.51.13 1 FULL/BDR 00:00:35 10.81.0.5 FastEthernet0
172.16.51.6 0 FULL/ - 00:00:32 172.16.51.6 Serial1
172.16.51.2 0 FULL/ - 00:00:30 172.16.51.2 Serial0

TownHall>sh ip ospf data

OSPF Router with ID (172.16.51.5) (Process ID 1)

Router Link States (Area 0)

Link ID ADV Router Age Seq# Checksum Link count
172.16.51.2 172.16.51.2 198 0x8000002C 0x00F6AF 3
172.16.51.5 172.16.51.5 1249 0x80000031 0x00EA8A 5
172.16.51.6 172.16.51.6 900 0x8000001A 0x00A320 2
172.16.51.10 172.16.51.10 1549 0x8000002D 0x001E7A 2
172.16.51.13 172.16.51.13 1291 0x8000002E 0x000A2C 5
172.16.51.14 172.16.51.14 1483 0x8000001C 0x009009 2

Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum
10.81.0.1 172.16.51.5 1998 0x80000019 0x00B02E

Type-5 AS External Link States

Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 172.16.51.5 1998 0x80000026 0x00D9BE 1

---------------------------------------------------------

TownHall2>sh ip ospf nei

Neighbor ID Pri State Dead Time Address Interface
172.16.51.5 1 FULL/DR 00:00:35 10.81.0.1 FastEthernet0
172.16.51.14 0 FULL/ - 00:00:39 172.16.51.14 Serial1
172.16.51.10 0 FULL/ - 00:00:37 172.16.51.10 Serial0

TownHall2>sh ip ospf data

OSPF Router with ID (172.16.51.13) (Process ID 1)

Router Link States (Area 0)

Link ID ADV Router Age Seq# Checksum Link count
172.16.51.2 172.16.51.2 262 0x8000002C 0x00F6AF 3
172.16.51.5 172.16.51.5 1313 0x80000031 0x00EA8A 5
172.16.51.6 172.16.51.6 964 0x8000001A 0x00A320 2
172.16.51.10 172.16.51.10 1611 0x8000002D 0x001E7A 2
172.16.51.13 172.16.51.13 1353 0x8000002E 0x000A2C 5
172.16.51.14 172.16.51.14 1545 0x8000001C 0x009009 2

Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum
10.81.0.1 172.16.51.5 44 0x8000001A 0x00AE2F

Type-5 AS External Link States

Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 172.16.51.5 44 0x80000027 0x00D7BF 1

---------------------------------------------------------

HighSchool>sh ip ospf nei

Neighbor ID Pri State Dead Time Address Interface
172.16.51.5 1 FULL/ - 00:00:33 172.16.51.1 Serial0

HighSchool>sh ip ospf data

OSPF Router with ID (172.16.51.2) (Process ID 1)

Router Link States (Area 0)

Link ID ADV Router Age Seq# Checksum Link count
172.16.51.2 172.16.51.2 339 0x8000002C 0xF6AF 3
172.16.51.5 172.16.51.5 1392 0x80000031 0xEA8A 5
172.16.51.6 172.16.51.6 1043 0x8000001A 0xA320 2
172.16.51.10 172.16.51.10 1692 0x8000002D 0x1E7A 2
172.16.51.13 172.16.51.13 1434 0x8000002E 0xA2C 5
172.16.51.14 172.16.51.14 1627 0x8000001C 0x9009 2

Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum
10.81.0.1 172.16.51.5 123 0x8000001A 0xAE2F

Type-5 AS External Link States

Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 172.16.51.5 123 0x80000027 0xD7BF 1

----------------------------------------------------------

PublicWorks>sh ip ospf nei

Neighbor ID Pri State Dead Time Address Interface
172.16.51.13 0 FULL/ - 00:00:32 172.16.51.9 Serial0

PublicWorks>sh ip ospf data

OSPF Router with ID (172.16.51.10) (Process ID 1)

Router Link States (Area 0)

Link ID ADV Router Age Seq# Checksum Link count
172.16.51.2 172.16.51.2 394 0x8000002C 0x00F6AF 3
172.16.51.5 172.16.51.5 1445 0x80000031 0x00EA8A 5
172.16.51.6 172.16.51.6 1096 0x8000001A 0x00A320 2
172.16.51.10 172.16.51.10 1741 0x8000002D 0x001E7A 2
172.16.51.13 172.16.51.13 1485 0x8000002E 0x000A2C 5
172.16.51.14 172.16.51.14 1677 0x8000001C 0x009009 2

Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum
10.81.0.1 172.16.51.5 176 0x8000001A 0x00AE2F

Type-5 AS External Link States

Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 172.16.51.5 176 0x80000027 0x00D7BF 1

---------------------------------------------------------

 

[drewdown]

Yes you need static routes, otherwise where would packets without a known destiation go?

 

[Tony414]

Ok. jneiberger had mentioned I have some unnecessary routes so I was unsure. Thanks for the info...

 

[jneiberger]

No, you don't need static routes. You're going to be advertising a default route via OSPF.

Tony, I was referring earlier to unnecessary network statements in your config. You only need network statements for interface on that router. On two of your routers, you have network statements for subnets that exist on other routers. Those are unnecessary.

I'm sorry I didn't get back to this last night. I'll take a look at your configs again now. I want to see why you don't have more 10.x.x.x subnets in your OSPF database.

 

[drewdown]

jneilberger is correct, you dont need static routes, you need default...I read static and thought default.

My bad.

 

[Tony414]

No problem everyone. I appreciate the help so I can wait

 

[jneiberger]

Okay, here are a few corrections you need to make.

On your PublicWorks router, you need a network statement for 10.101.0.1 and you need to remove the network statements for 10.81.x.x and 10.111.x.x.

On your HighSchool router, add a network statement for 10.0.0.20 and remove the statements for 10.81.x.x, 10.101.x.x and 10.111.x.x.

What do the configs on your ParkRec and PD routers look like?

 

[Tony414]

The ParkRec and PD routers are pretty much the same. I'm getting the idea now. I need a network statement for THAT router, correct? If PublicWork lan is 10.101.X.X then the network statement would be the same. Should it be like this
network 10.101.0.1 0.0.0.0 area 0 or
network 10.101.0.0 0.0.255.255 area 0 ?

 

[jneiberger]

On each router, you should have a network statement for each interface on THAT router. You don't need network statements for networks/interfaces on other routers.

I prefer using a 0.0.0.0 mask. I think that's "best practice" because it is more specific, but it's up to you. That's just my opinion and preference.