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kinwai
Beginner

External route not installed in OSPF?

Distributed a static route from another router.

 

The router with the problem shows the following, some of the routers are able to install the same routes successfully.

 

Router#sh ip ospf database external 7.7.7.0

OSPF Router with ID (10.10.1.5) (Process ID 100)

Type-5 AS External Link States

LS age: 1627
Options: (No TOS-capability, DC, Upward)
LS Type: AS External Link
Link State ID: 7.7.7.0 (External Network Number )
Advertising Router: 10.10.1.15
LS Seq Number: 80000002
Checksum: 0xDFB3
Length: 36
Network Mask: /24
Metric Type: 2 (Larger than any link state path)
MTID: 0
Metric: 0
Forward Address: 0.0.0.0

External Route Tag: 0

 

Router#sh ip route 10.10.1.15
Routing entry for 10.10.1.15/32
Known via "ospf 100", distance 110, metric 11, type intra area
Last update from 10.10.1.57 on Port-channel12.4, 4d14h ago
Routing Descriptor Blocks:
* 10.10.1.57, from 10.10.1.15, 4d14h ago, via Port-channel12.4
Route metric is 11, traffic share count is 1

I have similar same external route with /32 but installed in routing table successfully.

 

Router#sh ip ospf database external 6.6.6.242

OSPF Router with ID (10.10.1.15) (Process ID 100)

Type-5 AS External Link States

LS age: 904
Options: (No TOS-capability, DC, Upward)
LS Type: AS External Link
Link State ID: 6.6.6.242 (External Network Number )
Advertising Router: 10.10.1.15
LS Seq Number: 800007C6
Checksum: 0x5870
Length: 36
Network Mask: /32
Metric Type: 2 (Larger than any link state path)
MTID: 0
Metric: 0
Forward Address: 0.0.0.0
External Route Tag: 0

 

 

6 REPLIES 6
Georg Pauwen
VIP Expert

Hello,

 

post the full running configs of both the redistributing as well as the receiving router. What IOS version are both routers running ?

paul driver
VIP Mentor

Hello

 


@kinwai wrote:

Router#sh ip ospf database external 7.7.7.0

OSPF Router with ID (10.10.1.5) (Process ID 100)

Type-5 AS External Link States

LS age: 1627
Options: (No TOS-capability, DC, Upward)  <  Advertising the routers option capabilities to other routers in hello packet, stating older TOS capability isn’t supported, but on demand circuits(DC) are.

.LS Type: AS External Link
Link State ID: 7.7.7.0 (External Network Number )
Advertising Router: 10.10.1.15  <- Router id of router that orignated this LSA
LS Seq Number: 80000002
Checksum: 0xDFB3
Length: 36
Network Mask: /24
Metric Type: 2 (Larger than any link state path)
MTID: 0
Metric: 0
Forward Address: 0.0.0.0  < when set to 0 forward packet to the ASBR that orignated this LSA

External Route Tag: 0

 


Edited- some of the routers are able to install the same routes successfully.
Can your confirm the area type of these other routers?



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future

Hi Paul, they are all type 5 advertisments. My guess is , it could be due to BGP?

(In the far end, i have a juniper router which i redistributed static into ospf)

 

In fact, i'm running BGP and this path is available via eBGP. I would like to have this path routed via the subnet routed via a IPLC therefore I'm advertising it within the OSPF network.

 

Here's something i discovered (On another router)

-> When the BGP pref for this path is left at default (100), the ospf path appears.

Router#show route 7.7.7.1

Routing entry for 7.7.7.0/24
Known via "ospf 100", distance 110, metric 0, type extern 2
Installed Sep 28 16:51:17.376 for 00:00:03
Routing Descriptor Blocks
x.x.x.x, from 10.10.1.15, via TenGigE0/0/0/38.7
Route metric is 0
No advertising protos.

 

If i increased the BGP pref, the route to this path is via eBGP.

Routing entry for 7.7.7.0/24
Known via "bgp xxxxx", distance 20, metric 0
Tag 6939, type external
Installed Sep 28 16:30:17.333 for 00:21:00
Routing Descriptor Blocks
x.x.x.x, from x.x.x.x, BGP external
Route metric is 0
No advertising protos.

 

 

 

I guess i'm even more confused now. Isn't the distance the lower, the better?

In theory, eBGP have a lower administrative distance than OSPF? Why routes from OSPF appeared in the first place?

 

I googled around, there's some topic about weight but i don't think it is in use here?

 

 

 

 

Hello,

 

you say that some of the other routers successfully install the redistributed route. Are the routers in the same area ? It would be helpful to have a topology diagram  showing which routers do work, and the position of the router that does not work...

Hello @kinwai ,

for the monent the only thing that is clear is that the OSPF ASBR node is in the SAME area as the router that does not installe the LSA type 5 for prefix 7.7.7.0/24.

 

>>Router#sh ip route 10.10.1.15
Routing entry for 10.10.1.15/32
Known via "ospf 100", distance 110, metric 11, type intra area
Last update from 10.10.1.57 on Port-channel12.4, 4d14h ago
Routing Descriptor Blocks:
* 10.10.1.57, from 10.10.1.15, 4d14h ago, via Port-channel12.4
Route metric is 11, traffic share count is 1

Apart from this, the network scenario is not clear

 

>>

(In the far end, i have a juniper router which i redistributed static into ospf)

 

In fact, i'm running BGP and this path is available via eBGP. I would like to have this path routed via the subnet routed via a IPLC therefore I'm advertising it within the OSPF network.

 

At this point you should provide a network diagram where you report also the BGP sessions and their type eBGP or iBGP.

 

On what router have you increased the local preference ?

Be aware  that local preference does not travel to another BGP AS ?

 

OSPF ASBR 10.10.1.15 has also BGP sessions ?

 

Be also aware that you have a multivendor environment and that Juniper devices behave differently:

in JUNOS route preference  ( a 32 bit integer) is used in the same way as Cisco AD ( single byte 8 bit integer) the lowest the best.

JUNOS does not differentiate route preference between iBGP and eBGP . JUNOS uses different route preference values for OSPF internal routes and OSPF external routes.

 

Cisco uses different values of AD for iBGP 200 and eBGP 20 and uses same value 110 for all types of OSPF routes.

 

Hope to help

Giuseppe

 

 

 

MHM Cisco World
Collaborator

can you draw topology ?