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Redistributing BGP aggregated routes int OSPF

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grock
Level 1
Level 1

‎02-05-2019 12:38 PM

Aloha,

 

I ran into a issue at work, and labbed it to see where is the error. 

 

Router 1 and Router 2 are sending BGP aggregated routes into Router 3

Router 1 is sending 10.200.10.0/24 Router 2 is sending 10.200.20.0/24

Router 3 redistributes all BGP routes into Router 4 via OSPF

Router 4 receives the aggregated routes via OSPF and redistributes into Router 5 via BGP

However I do not see the routes being sent out to router 5 using soft-configuration from R4 and I obviously do not see Router 5 receiving the aggregated routes via the soft-configuration command from R4

 

I can ping everything behind Router 1 and Router 2 from Router 4, however, can't ping from R5 to R1 or R2

 

Is this a bug on GNS3? The configuration looks good to me. I think there is an issue redistributing BGP sourced aggregated routes into OSPF? Because when I remove the redistribution from R4 to R5, R5 looses all its redistrubuted learned routes from R4. So this indicates that redistribution seems to be working correctly. Seems like only the aggregated routes is not being redistributed.

 

R4 routing configuration:

 

router ospf 100

 log-adjacency-changes

 redistribute bgp 80 subnets

 passive-interface default

 no passive-interface GigabitEthernet0/0

 network 10.200.70.0 0.0.0.3 area 0

 network 10.200.80.10 0.0.0.0 area 0

 network 10.200.80.20 0.0.0.0 area 0

router bgp 80

 no synchronization

 bgp log-neighbor-changes

 network 10.200.80.30 mask 255.255.255.255

 network 172.17.1.0 mask 255.255.255.252

 redistribute ospf 100

 neighbor 172.17.1.255 remote-as 100

 neighbor 172.17.1.255 description ASB-EDGE

 neighbor 172.17.1.255 ebgp-multihop 2

 neighbor 172.17.1.255 soft-reconfiguration inbound

 no auto-summary

 

Router 4 ip route table

 

   172.17.0.0/16 is variably subnetted, 7 subnets, 2 masks

S       172.17.1.255/32 [1/0] via 172.17.1.2

B       172.17.1.40/32 [20/0] via 172.17.1.255, 00:30:59

B       172.17.1.30/32 [20/0] via 172.17.1.255, 00:30:59

B       172.17.1.20/32 [20/0] via 172.17.1.255, 00:30:59

B       172.17.1.10/32 [20/0] via 172.17.1.255, 00:30:59

C       172.17.1.0/30 is directly connected, GigabitEthernet1/0

B       172.17.2.0/30 [20/0] via 172.17.1.255, 00:30:59

     10.0.0.0/8 is variably subnetted, 16 subnets, 3 masks

C       10.200.70.0/30 is directly connected, GigabitEthernet0/0

C       10.200.80.20/32 is directly connected, Loopback20

C       10.200.80.30/32 is directly connected, Loopback30

C       10.200.80.10/32 is directly connected, Loopback10

O E2    10.200.50.70/32 [110/1] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O       10.200.50.50/32 [110/3] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O E2    10.200.10.0/30 [110/1] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O E2    10.200.10.0/24 [110/1] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O       10.200.60.40/32 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O E2    10.200.20.0/30 [110/1] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O E2    10.200.20.0/24 [110/1] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O       10.200.60.30/32 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O       10.200.60.20/32 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O       10.200.50.0/30 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O       10.200.60.10/32 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

O       10.200.60.0/30 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

 

Router 4 BGP table

 

   Network          Next Hop            Metric LocPrf Weight Path

*> 10.200.50.0/30   10.200.70.2              2         32768 ?

*> 10.200.50.50/32  10.200.70.2              3         32768 ?

*> 10.200.60.0/30   10.200.70.2              2         32768 ?

*> 10.200.60.10/32  10.200.70.2              2         32768 ?

*> 10.200.60.20/32  10.200.70.2              2         32768 ?

*> 10.200.60.30/32  10.200.70.2              2         32768 ?

*> 10.200.60.40/32  10.200.70.2              2         32768 ?

*> 10.200.70.0/30   0.0.0.0                  0         32768 ?

*> 10.200.80.10/32  0.0.0.0                  0         32768 ?

*> 10.200.80.20/32  0.0.0.0                  0         32768 ?

*> 10.200.80.30/32  0.0.0.0                  0         32768 i

*> 172.17.1.0/30    0.0.0.0                  0         32768 i

*> 172.17.1.10/32   172.17.1.255             0             0 100 ?

*> 172.17.1.20/32   172.17.1.255             0             0 100 ?

*> 172.17.1.30/32   172.17.1.255             0             0 100 i

*> 172.17.1.40/32   172.17.1.255             0             0 100 i

*> 172.17.2.0/30    172.17.1.255             0             0 100 ?

 

 

Router 5 routing configuration:

 

router bgp 100

 no synchronization

 bgp log-neighbor-changes

 network 172.17.1.0 mask 255.255.255.255

 network 172.17.1.30 mask 255.255.255.255

 network 172.17.1.40 mask 255.255.255.255

 redistribute eigrp 200

 neighbor 172.17.1.1 remote-as 80

 neighbor 172.17.1.1 description HT-ASB-PE

 neighbor 172.17.1.1 soft-reconfiguration inbound

 no auto-summary

 

Router 5 routing table 

 

Gateway of last resort is not set

 

     172.17.0.0/16 is variably subnetted, 7 subnets, 2 masks

C       172.17.1.255/32 is directly connected, Loopback100

C       172.17.1.40/32 is directly connected, Loopback40

C       172.17.1.30/32 is directly connected, Loopback30

C       172.17.1.20/32 is directly connected, Loopback20

C       172.17.1.10/32 is directly connected, Loopback10

C       172.17.1.0/30 is directly connected, FastEthernet0/0

C       172.17.2.0/30 is directly connected, FastEthernet0/1

     10.0.0.0/8 is variably subnetted, 11 subnets, 2 masks

B       10.200.70.0/30 [20/0] via 172.17.1.1, 00:11:22

B       10.200.80.20/32 [20/0] via 172.17.1.1, 00:11:22

B       10.200.80.30/32 [20/0] via 172.17.1.1, 00:26:34

B       10.200.80.10/32 [20/0] via 172.17.1.1, 00:11:22

B       10.200.50.50/32 [20/3] via 172.17.1.1, 00:11:22

B       10.200.60.40/32 [20/2] via 172.17.1.1, 00:11:22

B       10.200.60.30/32 [20/2] via 172.17.1.1, 00:11:22

B       10.200.60.20/32 [20/2] via 172.17.1.1, 00:11:22

B       10.200.50.0/30 [20/2] via 172.17.1.1, 00:11:22

B       10.200.60.10/32 [20/2] via 172.17.1.1, 00:11:22

B       10.200.60.0/30 [20/2] via 172.17.1.1, 00:11:22

 

Router 5 BGP table

 

   Network          Next Hop            Metric LocPrf Weight Path

*> 10.200.50.0/30   172.17.1.1               2             0 80 ?

*> 10.200.50.50/32  172.17.1.1               3             0 80 ?

*> 10.200.60.0/30   172.17.1.1               2             0 80 ?

*> 10.200.60.10/32  172.17.1.1               2             0 80 ?

*> 10.200.60.20/32  172.17.1.1               2             0 80 ?

*> 10.200.60.30/32  172.17.1.1               2             0 80 ?

*> 10.200.60.40/32  172.17.1.1               2             0 80 ?

*> 10.200.70.0/30   172.17.1.1               0             0 80 ?

*> 10.200.80.10/32  172.17.1.1               0             0 80 ?

*> 10.200.80.20/32  172.17.1.1               0             0 80 ?

*> 10.200.80.30/32  172.17.1.1               0             0 80 i

r> 172.17.1.0/30    172.17.1.1               0             0 80 i

*> 172.17.1.10/32   0.0.0.0                  0         32768 ?

*> 172.17.1.20/32   0.0.0.0                  0         32768 ?

*> 172.17.1.30/32   0.0.0.0                  0         32768 i

*> 172.17.1.40/32   0.0.0.0                  0         32768 i

*> 172.17.2.0/30    0.0.0.0                  0         32768 ?

Labels:
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2 Accepted Solutions

Accepted Solutions

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Georg Pauwen
VIP
VIP

‎02-05-2019 12:53 PM

Hello,

 

not sure if this is a bug, what if you specifically configure:

 

R4

 

redistribute ospf 100 match internal external 1 external 2

View solution in original post

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Go to solution
grock
Level 1
Level 1
In response to Georg Pauwen

‎02-05-2019 01:31 PM

This is what I found online:

IOS will not redistribute OSPF external information into BGP by default (internal only). You need to apply the 'match internal external' switch to your redistribute statement to get this to work.

View solution in original post

0 Helpful
11 Replies 11

Go to solution
Georg Pauwen
VIP
VIP

‎02-05-2019 12:53 PM

Hello,

 

not sure if this is a bug, what if you specifically configure:

 

R4

 

redistribute ospf 100 match internal external 1 external 2

0 Helpful

Go to solution
grock
Level 1
Level 1
In response to Georg Pauwen

‎02-05-2019 01:02 PM

Wow! That worked. Strange. Is this a bug, or must this be configured in order to redistribute BGP sourced aggregated routes?
0 Helpful

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grock
Level 1
Level 1
In response to Georg Pauwen

‎02-05-2019 01:04 PM

Wow! That worked. Strange. Is this a bug, or must this be configured in order to redistribute BGP sourced aggregated routes?
0 Helpful

Go to solution
Georg Pauwen
VIP
VIP
In response to grock

‎02-05-2019 01:13 PM

Hello,

 

in theory, without the keywords, only OSPF intra-area and inter-area routes should have been redistributed into BGP. So you shoud get at least the 'O' routes.

 

Which IOS are you running this on in GNS3 ?

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grock
Level 1
Level 1
In response to Georg Pauwen

‎02-05-2019 01:16 PM

BOOTLDR: 7200 Software (C7200-ADVIPSERVICESK9-M), Version 12.4(24)T8, RELEASE SOFTWARE (fc1)

Prob IOS bug?? The only way I know of to run good up-to date IOS images, is by spinning up a VM. Ugh! I dont have resources for that.
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Georg Pauwen
VIP
VIP
In response to grock

‎02-05-2019 01:20 PM

Hello,

 

I am testing with 15.6(2)T...will let you know...

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grock
Level 1
Level 1
In response to Georg Pauwen

‎02-05-2019 01:31 PM

This is what I found online:

IOS will not redistribute OSPF external information into BGP by default (internal only). You need to apply the 'match internal external' switch to your redistribute statement to get this to work.
0 Helpful

Go to solution
Georg Pauwen
VIP
VIP
In response to grock

‎02-05-2019 01:40 PM

Exactly. So by default you get only the 'O' and 'O-IA' routes (the latter you don't have')...

Go to solution
Georg Pauwen
VIP
VIP
In response to Georg Pauwen

‎02-05-2019 01:35 PM

Hello,

 

it works as designed in 15(6)2T.

 

Actually, looking at the routing table of your R4 router and the routing table of your R5 router, I think all the redistributed 'O' routes are there ?

 

O 10.200.50.50/32 [110/3] via 10.200.70.2, 00:31:25, GigabitEthernet0/0
O 10.200.60.40/32 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0
O 10.200.60.30/32 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0
O 10.200.60.20/32 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0
O 10.200.50.0/30 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0
O 10.200.60.10/32 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0
O 10.200.60.0/30 [110/2] via 10.200.70.2, 00:31:25, GigabitEthernet0/0

 

B 10.200.70.0/30 [20/0] via 172.17.1.1, 00:11:22
B 10.200.80.20/32 [20/0] via 172.17.1.1, 00:11:22
B 10.200.80.30/32 [20/0] via 172.17.1.1, 00:26:34
B 10.200.80.10/32 [20/0] via 172.17.1.1, 00:11:22
B 10.200.50.50/32 [20/3] via 172.17.1.1, 00:11:22
B 10.200.60.40/32 [20/2] via 172.17.1.1, 00:11:22
B 10.200.60.30/32 [20/2] via 172.17.1.1, 00:11:22
B 10.200.60.20/32 [20/2] via 172.17.1.1, 00:11:22
B 10.200.50.0/30 [20/2] via 172.17.1.1, 00:11:22
B 10.200.60.10/32 [20/2] via 172.17.1.1, 00:11:22
B 10.200.60.0/30 [20/2] via 172.17.1.1, 00:11:22

Go to solution
grock
Level 1
Level 1
In response to Georg Pauwen

‎02-05-2019 02:20 PM

Yes. This is new to me since a lot of clients network I manage runs EIGRP versus OSPF. Knowledge added to the bucket. Thanks for your help Georg!
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grock
Level 1
Level 1
In response to Georg Pauwen

‎02-05-2019 02:35 PM

btw is this a OSPF flaw, BGP flaw, or by design?
0 Helpful
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