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Beginner

Extend L2 VLAN between two different locations

Hello, 

I have two sites are connected together through fiber, OSPF is configured on both core switches, now the problem is; I have VLAN needs to configured on both sites

Site A: VLAN 10, SVI 10.10.10.1

Site B: VLAN 10, SVI 10.10.10.2 

I can reach only one site although the VLAN has been allowed in the trunk between both sites.

Problem description;

From site A I can reach servers in site A (ex. 10.10.10.3) and from Site B i can reach (ex. 10.10.10.4) but from Site A i'm not able to reach 10.10.10.4 in site B, and even the SVI on site B is not reachable from Site A, now when i shutdown the SVI on Site A, Site B became reachable from Site A due to passing through OSPF as a L3 but site A became unreachable from Site B. 

Any advice please?

19 REPLIES 19
Highlighted

Re: Extend L2 VLAN between two different locations

 

Hi,

 

It looks like you are using the same network on both sites; that is the reason for connectivity failure between the two sites. If you share your configuration, we can provide more advise.

 

HTH,

Meheretab

Beginner

Re: Extend L2 VLAN between two different locations

I won't be able to share as is configuration but it looks like below; 

Core Switch site A: 

VLAN 20 

connected to site B

ip address 20.20.20.1 255.255.255.252

VLAN 10

ip address 10.10.10.1 255.255.255.0

interface po 1

trunk to Site B

switch port mode trunk 

switch port trunk allowed vlan 10 20

 

ospf 1

redistribute connected

redistribute static 

network 20.20.20.0 0.0.0.3 area 0.0.0.0

 

Core Switch site B: 

VLAN 20 

connected to site A

ip address 20.20.20.2 255.255.255.252

VLAN 10

ip address 10.10.10.2 255.255.255.0

interface po 1

trunk to Site A

switch port mode trunk 

switch port trunk allowed vlan 10 20

 

ospf 1

redistribute connected

redistribute static 

network 20.20.20.0 0.0.0.3 area 0.0.0.0

 

 

VIP Advocate

Re: Extend L2 VLAN between two different locations

Hi,

Are you using VPN between both sites? What type of connectivity is there?

There are multiple options as:

VXLAN, VLAN Mapping, NATing (One to One translate) etc. But I hope,  NATing would resolve your issue.

 

Regards,
Deepak Kumar,
Don't forget to vote and accept the solution If this comment will make help you!
Beginner

Re: Extend L2 VLAN between two different locations

Both sites are connected using backbone fiber and the vlan is tagged through the whole way but not working
Beginner

Re: Extend L2 VLAN between two different locations

is this straight link? if yes - can you see cdp neighbor?

sw 1 <----fiber-----> sw 2

Beginner

Re: Extend L2 VLAN between two different locations

No it's not a straight link, there are a few nodes on the road
Beginner

Re: Extend L2 VLAN between two different locations

Looks like you have port channel configured. Can you please check the status of this portchannel and the interfaces binded to it.

 

Quick question : is there any connectivity for other vlans between sites through this inter-link? Except vlan 10.

Beginner

Re: Extend L2 VLAN between two different locations

Yes there is another VLAN the one used to establish OSPF between both cores, no issue with the link itself or the port channel

Re: Extend L2 VLAN between two different locations

Can I know why you want to run OSPF when all devices are in same subnet?

Beginner

Re: Extend L2 VLAN between two different locations

It is possible that initially these were two different isolated sites with the same subnet (10.10.10.х/24), and the task of merging appeared later.

Beginner

Re: Extend L2 VLAN between two different locations

Actually there are a lot of other networks that needs to be redistributed using OSPF

Beginner

Re: Extend L2 VLAN between two different locations

if you want to redistribute static networks you need to use

 

redistribute connected subnets

Beginner

Re: Extend L2 VLAN between two different locations

They are already redistributed i have no issues with OSPF

Enthusiast

Re: Extend L2 VLAN between two different locations

Hi, 

i assume that you have directly connected backbone (fiber) between 2 networks. if i understood correctly. 

 

in this case, if you are using same VLAN and network ranges at both sites, you dont need to configure routing protocol to do routing. because both core switches are connected with L2 link. you can configure backbone as a trunk and allow VLANs you already have. also, in this case you have to use 1 switch as a L3 switch with SVIs for different VLAN gateways on inter vlan routing purpose. please correct me if i am understood in wrong way.

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