Re: ODDITY - OSPF E2 preferred above E1

Bits of the topology are missing and I can only go with a hunchb& With E2
route present, on your PE (R4?), what's the output of "show ip route vrf
TEST ospf"?

--
Marko Milivojevic - CCIE #18427 (SP R&S)
Senior CCIE Instructor / Managing Partner - IPexpert
On Thu, Apr 11, 2013 at 2:03 PM, bitje <lj_at_cli.nu> wrote:
> Hi,
>
> I have a situation where a E1 route is being overriden by a E2 route.
> The E1 route is entering the area from a mpls superbackbone and the
> E2 from an ASBR in the same area. According to what I know an E1
> route should always win from a E2 route.. I feel that I am going
> to learn something here.
>
> R5 is connected to SW2 and R4.
>
> On SW2 the following is done:
> !
> ip route 12.12.12.12 255.255.255.255 Null0
> !
> router ospf 100
>  router-id 0.0.0.8
>  log-adjacency-changes
>  redistribute static subnets
>  network 155.1.58.8 0.0.0.0 area 0
> !
>
> On R4 the following is done:
> !
> router ospf 100 vrf TEST
>  router-id 0.0.0.4
>  log-adjacency-changes
>  redistribute bgp 100 subnets
>  network 155.1.45.4 0.0.0.0 area 0
> !
> router bgp 100
>  no synchronization
>  bgp log-neighbor-changes
>  neighbor 6.6.6.6 remote-as 100
>  neighbor 6.6.6.6 update-source Loopback10
>  neighbor 204.12.1.254 remote-as 54
>  no auto-summary
>  !
>  address-family vpnv4
>   neighbor 6.6.6.6 activate
>   neighbor 6.6.6.6 send-community extended
>  exit-address-family
>  !
>  address-family ipv4 vrf TEST
>   no synchronization
>  exit-address-family
> !
>
> On R5 the following is done:
> !
> router ospf 100
>  router-id 0.0.0.5
>  log-adjacency-changes
>  network 155.1.45.5 0.0.0.0 area 0
>  network 155.1.58.5 0.0.0.0 area 0
> Rack1R5#
>
> Some relevant show commands:
>
> Rack1R5#show ip route ospf 100
>      12.0.0.0/32 is subnetted, 1 subnets
> O E2    12.12.12.12 [110/20] via 155.1.58.8, 05:41:13, FastEthernet0/0
> Rack1R5#
>
> Rack1R5#show ip ospf database external 12.12.12.12
>
>             OSPF Router with ID (0.0.0.5) (Process ID 100)
>
>                 Type-5 AS External Link States
>
>   Routing Bit Set on this LSA
>   LS age: 1494
>   Options: (No TOS-capability, DC)
>   LS Type: AS External Link
>   Link State ID: 12.12.12.12 (External Network Number )
>   Advertising Router: 0.0.0.8
>   LS Seq Number: 8000000B
>   Checksum: 0x79E4
>   Length: 36
>   Network Mask: /32
>         Metric Type: 2 (Larger than any link state path)
>         TOS: 0
>         Metric: 20
>         Forward Address: 0.0.0.0
>         External Route Tag: 0
>
> Rack1R5#
>
> Rack1R5#show ip ospf database router 0.0.0.8
>
>             OSPF Router with ID (0.0.0.5) (Process ID 100)
>
>                 Router Link States (Area 0)
>
>   Routing Bit Set on this LSA
>   LS age: 1533
>   Options: (No TOS-capability, DC)
>   LS Type: Router Links
>   Link State ID: 0.0.0.8
>   Advertising Router: 0.0.0.8
>   LS Seq Number: 80000024
>   Checksum: 0xDF9B
>   Length: 36
>   AS Boundary Router
>   Number of Links: 1
>
>     Link connected to: a Transit Network
>      (Link ID) Designated Router address: 155.1.58.5
>      (Link Data) Router Interface address: 155.1.58.8
>       Number of TOS metrics: 0
>        TOS 0 Metrics: 200
>
>
> Rack1R5#
>
> Now if I remove the static route on SW2:
> Rack1SW2(config)#no ip route 12.12.12.12 255.255.255.255 Null0
>
> And ask R5 what external route it has we see that only after
> the static from SW2 has been removed R5 will accept the E1
> route since the E2 route is no longer available:
>
> Rack1R5#show ip ospf database external
>
>             OSPF Router with ID (0.0.0.5) (Process ID 100)
>
>                 Type-5 AS External Link States
>
>   Routing Bit Set on this LSA
>   LS age: 55
>   Options: (No TOS-capability, DC)
>   LS Type: AS External Link
>   Link State ID: 12.12.12.12 (External Network Number )
>   Advertising Router: 0.0.0.4
>   LS Seq Number: 80000001
>   Checksum: 0xF046
>   Length: 36
>   Network Mask: /32
>         Metric Type: 2 (Larger than any link state path)
>         TOS: 0
>         Metric: 20
>         Forward Address: 0.0.0.0
>         External Route Tag: 3489661028
>
> Rack1R5#
>
> Rack1R5#show ip ospf database router 0.0.0.4
>
>             OSPF Router with ID (0.0.0.5) (Process ID 100)
>
>                 Router Link States (Area 0)
>
>   Routing Bit Set on this LSA
>   LS age: 820
>   Options: (No TOS-capability, DC)
>   LS Type: Router Links
>   Link State ID: 0.0.0.4
>   Advertising Router: 0.0.0.4
>   LS Seq Number: 80000016
>   Checksum: 0xAB3C
>   Length: 48
>   Area Border Router
>   AS Boundary Router
>   Number of Links: 2
>
>     Link connected to: another Router (point-to-point)
>      (Link ID) Neighboring Router ID: 0.0.0.5
>      (Link Data) Router Interface address: 155.1.45.4
>       Number of TOS metrics: 0
>        TOS 0 Metrics: 64
>
>     Link connected to: a Stub Network
>      (Link ID) Network/subnet number: 155.1.45.0
>      (Link Data) Network Mask: 255.255.255.0
>       Number of TOS metrics: 0
>        TOS 0 Metrics: 64
>
>
> Rack1R5#
>
> Your analysis/help is appreciated.
>
> Regards
>
>
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