[Xorp-users] Issues related to OSPF path selection
Atanu Ghosh
atanu at ICSI.Berkeley.EDU
Mon Jun 30 08:26:10 PDT 2008
Hi,
Could you try this experiment with the latest code from CVS.
Atanu.
arvind <arvind at macil.in> wrote:
>
>
>
> A , B--> Server running router manager with 2 ethernet ports (With OSPF)
> C------> Its a server running router manager with 10 ethernet ports(with
> static and OSPF protocols)
>
>
> This picture May not be clear in some systems for those I have explained
> the setup below.
>
> _________ _________ | | 172.16.3.1 172.16.3.2 | |
> | A 1|<----------------------------->|1 B |
> | 0 | | 0 | --------- --------- 172.16.2.1 ^
> ^ 172.16.1.1
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | _________ | | | | |
> ----------->| C |<-----------------
> 172.16.2.2 | | 172.16.1.2
> ---------
>
>
>
> Server C has the following in configuration file:
>
>
> protocols {
> static {
> disable: false
> route 10.10.10.0/24 {
> next-hop: 172.16.10.10
> metric: 1
> }
> route 10.10.11.0/24 {
> next-hop: 172.16.11.10
> metric: 1
> }
> }
> ospf4 {
> router-id: 172.16.1.2
> area 0.0.0.0 {
> interface eth2 {
> vif eth2.0 {
> address 172.16.2.2 {
> }
> }
> }
> interface eth4 {
> vif eth4.0 {
> address 172.16.1.2 {
> }
> }
> }
> }
> export: "connected,static"
> }
> }
>
> policy {
> policy-statement connected {
> term export {
> from {
> protocol: "connected"
> }
> }
> }
> policy-statement static {
> term export {
> from {
> protocol: "static"
> }
> }
> }
> }
>
> interfaces {
> restore-original-config-on-shutdown: true
> interface eth0 {
> disable: false
> discard: false
> description: "data interface"
> mac: 00:bb:cc:dd:ee:00
> mtu: 1500
> vif eth0.0 {
> disable: false
> vlan {
> vlan-id: 0
> }
> address 172.16.10.2 {
> prefix-length: 24
> broadcast: 172.16.10.255
> disable: false
> }
> }
> }
> interface eth1 {
> disable: false
> discard: false
> description: "data interface"
> mac: 00:bb:cc:dd:ee:01
> mtu: 1500
> vif eth1.0 {
> disable: false
> vlan {
> vlan-id: 0
> }
> address 172.16.11.2 {
> prefix-length: 24
> broadcast: 172.16.11.255
> disable: false
> }
> }
> }
> interface eth2 {
> disable: false
> discard: false
> description: "data interface"
> mac: 00:bb:cc:dd:ee:02
> mtu: 1500
> vif eth2.0 {
> disable: false
> vlan {
> vlan-id: 0
> }
> address 172.16.2.2 {
> prefix-length: 24
> broadcast: 172.16.2.255
> disable: false
> }
> }
> }
> interface eth4 {
> disable: false
> discard: false
> description: "data interface"
> mac: 00:bb:cc:dd:ee:04
> mtu: 1500
> vif eth4.0 {
> disable: false
> vlan {
> vlan-id: 0
> }
> address 172.16.1.2 {
> prefix-length: 24
> broadcast: 172.16.1.255
> disable: false
> }
> }
> }
> }
>
>
>
> I will explain the set-up (the Above diagram may not be clear while
> receiving)
> 3 systems are there running with router manager A,B,C
>
> A and B is connected with the network 172.16.3.1 nad 172.16.3.2
>
> A and C is connected with the network 172.16.2.1 nad 172.16.2.2
>
> B and C is connected with the network 172.16.1.1 nad 172.16.1.2
>
>
> After running router manager in all the systems the OSPF states are
> "full" and the "show route table ipv4 unicast ospf" is showing the
> shortest path.But the issue is whenever the path is remove/broken (2 or
> 3 times) between any 2 systems and replacing then the back again it was
> not showing the shortest path..
>
>
> By giving "clear ospf database" the shortest paths are coming back again.
>
>
>
>
> My Test:
> I remove the path between A and C and replaced it back again but it was
> not showing the shortest path.
>
> Output checked in A:
> output before removing the connection:
>
>
> root at test1> show ospf4 neighbor
> Address Interface State ID Pri
> Dead
> 172.16.2.2 eth0/eth0 Full 172.16.1.2 128 30
> 172.16.3.2 eth1/eth1 Full 172.16.1.1 128 30
>
> root at test1> show route table ipv4 unicast ospf
> 10.10.10.0/24 [ospf(110)/1]
> > to 172.16.2.2 via eth0/eth0
> 10.10.11.0/24 [ospf(110)/1]
> > to 172.16.2.2 via eth0/eth0
> 172.16.1.0/24 [ospf(110)/2]
> > to 172.16.3.2 via eth1/eth1
> 172.16.10.0/24 [ospf(110)/1]
> > to 172.16.2.2 via eth0/eth0
> 172.16.11.0/24 [ospf(110)/1]
> > to 172.16.2.2 via eth0/eth0
> root at test1>
>
>
>
>
>
> output after removing the connection:
>
> root at test1> show ospf4 neighbor
> Address Interface State ID Pri
> Dead
> 172.16.2.2 eth0/eth0 Down 172.16.1.2 0 0
> 172.16.3.2 eth1/eth1 Full 172.16.1.1 128 38
>
> root at test1> show route table ipv4 unicast ospf
> 10.10.10.0/24 [ospf(110)/1]
> > to 172.16.3.2 via eth1/eth1
> 10.10.11.0/24 [ospf(110)/1]
> > to 172.16.3.2 via eth1/eth1
> 172.16.1.0/24 [ospf(110)/2]
> > to 172.16.3.2 via eth1/eth1
> 172.16.10.0/24 [ospf(110)/1]
> > to 172.16.3.2 via eth1/eth1
> 172.16.11.0/24 [ospf(110)/1]
> > to 172.16.3.2 via eth1/eth1
> root at test1>
>
>
> Its fine still now, but the problem is after replacing the path between
> A and C, It was not taking....
>
>
>
>
> output after replacing the connection:
>
>
> root at test1> show route table ipv4 unicast ospf
> 10.10.10.0/24 [ospf(110)/1]
> > to 172.16.3.2 via eth1/eth1
> 10.10.11.0/24 [ospf(110)/1]
> > to 172.16.3.2 via eth1/eth1
> 172.16.1.0/24 [ospf(110)/2]
> > to 172.16.3.2 via eth1/eth1
> 172.16.10.0/24 [ospf(110)/1]
> > to 172.16.3.2 via eth1/eth1
> 172.16.11.0/24 [ospf(110)/1]
> > to 172.16.3.2 via eth1/eth1
> root at test1>
>
>
>
>
> If I give "clear ospf database" and then "show route table ipv4 unicast
> ospf" then the paths are coming as shortest path.
>
>
> At this situation If I remove the path between C and B,
>
> System A doesnot know any route about the neighbors.
>
>
>
> Can any one give the solution/idea for the above problem.
>
>
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