From: Tim Fletcher (tim@fletchmail.net)
Date: Thu Mar 20 2003 - 12:19:01 GMT-3
Hunt,
The address in the virtual link statement is the remote router ID, not the
address of the other router. Once the adjacency between R1 and R2 is
established, R2 will know the router ID for R1 and be able to establish the
virtual link.
To better understand this, try changing the router id on R1 to something
else, like 1.0.0.0 (it doesn't even have to be a legitimate IP address),
and changing the virtual link statement to the same address. After
resetting the OSPF process, your virtual link should come up fine.
This is one of the reasons why many people suggest locking down the OSPF
router ID. If you added a 2nd loopback with a higher numbered address your
virtual link would not come up after a reload because the router ID would
change.
-Tim Fletcher
At 12:16 AM 3/21/2003 +1100, Hunt Lee wrote:
>Hi group,
>
>I'm confused on the following eg.
>
> <--- Area 2 ----->
>
> Trunk VLAN30
>11.1.1.1---R1 --- Cat 3550 ---- R2---200.200.200.1
>(Area 11) |
> |
> |
> other OSPF routers (OSPF Area 0)
>
>R2 is advertising a default route out to OSPF
>by: ip route 0.0.0.0 0.0.0.0 137.20.20.2
>
>Both 11.1.1.1 & 200.200.200.1 are Loopback interface by R1 and R2
>respectively
>
>I scratched my head as to how can R2 establish a virtual-link to R1 with IP
>11.1.1.1, where 11.1.1.1 is in Area 11, since I was expecting that R2
>won't be able
>to know about 11.1.1.1 until the Virtual-Link is formed...
>
>At R2:-
>
>interface Loopback0
> ip address 200.200.200.1 255.255.255.0
>
>interface Ethernet0
> ip address 137.20.20.1 255.255.255.0
> ip ospf priority 200
>
>router ospf 1
> router-id 200.200.200.1
> log-adjacency-changes
> area 2 virtual-link 11.1.1.1 <---- How can R2 see 11.1.1.1
> network 137.20.20.1 0.0.0.0 area 2
> network 150.100.32.2 0.0.0.0 area 0
> default-information originate metric 100 metric-type 1
>
>At R1:-
>
>interface Loopback0
> ip address 11.1.1.1 255.255.255.0
>
>interface FastEthernet0/0.1
> encapsulation dot1Q 10
> ip address 192.168.1.11 255.255.255.224
>!
>interface FastEthernet0/0.2
> encapsulation dot1Q 20
> ip address 10.90.1.11 255.255.255.0
>!
>interface FastEthernet0/0.3
> encapsulation dot1Q 30
> ip address 137.20.20.11 255.255.255.0
>!
>router ospf 1
> router-id 11.1.1.1
> log-adjacency-changes
> area 2 virtual-link 200.200.200.1
> summary-address 192.168.1.0 255.255.255.0
> network 11.1.1.1 0.0.0.0 area 11
> network 137.20.20.11 0.0.0.0 area 2
>
>
>And at 3550:-
>
>interface FastEthernet0/2
> description R2
> switchport access vlan 30
> switchport mode access
> no ip address
>
>interface FastEthernet0/14
> description R1's Trunk port
> switchport trunk encapsulation dot1q
> switchport trunk allowed vlan 1-39,184-4094
> switchport mode trunk
> no ip address
> duplex full
> speed 100
>
>Regards,
>Lee
>
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This archive was generated by hypermail 2.1.4 : Sat Apr 05 2003 - 08:51:42 GMT-3