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Make ports on two different switches look like physically wired


I have two different switches in two different buildings and I need to make the ports look like there is a physical wire between them.

I have two disjoint networks that can talk to each other through a firewall but I need to be able to easily pass multicast traffic. I have a single PC in one building on my network (network A) and it needs to look like it is wired into the other network (network B) that resides in another building. My biggest problem is that the subnets on Network B (10.129.x.x/24) overlap with the management vlan (10.x.x.x/8) on my network. I have attempted to put all of the ports on Network A and Network B on the same vlan, however I could get no traffic to pass and I believe this is a problem with the overlap. Any help would be appreciated.

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6 REPLIES
Hall of Fame Super Blue

Make ports on two different switches look like physically wired

Justin

Do you mean you want the same vlan using the same IP subnet available on both switches ?

If so it sounds like you have a firewall in between. Unless that firewall is in transparent mode then it won't work because a firewall in normal routed mode acts a L3 hop and so you have a L3 link connection between your switches. If so you cannot route to the same IP subnet ie. if a device in a subnet wants to communicate with another device in the same subnet then it L2 switches it does not L3 route/switch.

Perhaps you could clarfiy the setup but it does sound as though that is your problem from what you have desribed.

Jon

New Member

Re: Make ports on two different switches look like physically wi

My setup is as follows


Network A
Switch 1 (same location as Network B )- c3750v2 port f1/0/1
Switch 2 - (different building) c3750v2 port f1/0/1
Native/management Vlan - 10.x.x.x/8
Network B
Cisco 6506
Vlan 4 10.129.x.x/24

I want to connect a port from switch 1 to the Network B 6506. Then connect the switchport on Switch 2 to the PC and have the PC have an ip on the Netowrk B Vlan 4. The issue that I see is that the vlan 4 subnet overlaps with management network of Network A. The firewall comment was erroneous I think. I am trying to create a route to the PC without going through the firewall. Also I need to be able to pull up multicast traffic from Vlans on Network B.



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Hall of Fame Super Blue

Re: Make ports on two different switches look like physically wi

So is there a current connection between switch 1 and switch 2 and what vlan is it in or is it a trunk link.

If you want the PC to be in vlan 4 then -

1) the connection between switch 1 and switch 2 needs to be in vlan 4 at both ends or if it is a trunk link then it needs to allow vlan 4

2) the connection between switch 1 and the 6500 for both ends needs to be in vlan 4

then it should work because the PC has a direct path in vlan 4 to the 6500. The fact that there is an overlap in IP addressing doesn't matter because the PC is not routing off switch 2 but off the 6500.

Not sure how this relates to multicast traffic though. Do you mean there are multicast sources in vlan B and you need the PC to be able to receive them.

Jon

New Member

Re: Make ports on two different switches look like physically wi

I thought that would work, however when it was set up, no traffic would pass. There is fiber that goes from Switch 1 to the Network A core switch(c6506-e) and then from there to switch another switch before making one last fiber jump to Switch 2. All of the fiber ports are trunk uplinks with all Vlans allowed.

Netowrk B 6506 --(cat5e)--> Switch 1 --(SM fiber)--> Network A 6506 --(SM fiber)--> another 3750v2 --(MM fiber)--> Switch 2. --(cat5e)--> PC

All links except the cat5e are trunk ports and the cat5e links are vlan 4.

Network B is comprised of a lot of cameras that are displayed in our system by pulling up their multicast streams. The PC needs to be able to access the streams.

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Hall of Fame Super Blue

Make ports on two different switches look like physically wired

Justin

It should work.

Can you check that vlan 4 exists in all the vlan databases on all the switches ie. just being allowed on the trunk link is not enough.

Jon

New Member

Re: Make ports on two different switches look like physically wi

I will look again, however all of the switches in Network A are supposed to be members of the same VTP domain and the Network A 6506 has it. Also I know the Network B 6506 has it as well.

Thank you for your help on this. Maybe one of the switches wasn't joined to the VTP domain.

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