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New Member

Connecting two sites

Hi,

I've got a problem with this situation and I hope someone can help me. There are two sites (S1, S2) that have got two separate networks:

- S1 has got Cisco 6509 as a core switch and it does all the inter-vlan routing. There are vlans 10-100 and vlan 150 for management.

- S2 is much smaller, it's got 3550-12T as a core device and there are only two vlans 200, 210 and vlan 250 for management.

Those two networks are to be connected (a link between 6509 and 3550) and I'm not too sure how to do it.

I was thinking about using routing ports on each switches and adding some static routes, but I've got few issues with that.

I'd like to have all switches in one management vlan so I want to replace vlan 250 at site S2 with vlan 150.

I'd like to keep all other vlans as they are now and preferably to keep them locally at their sites.

I tried to achieve both targets using my test equipment, but I just can't make it work. If I use routing ports, I can't have one subnet for switches (same subnet at both sites). If I configure the link as trunk, then I need to move vlans 200 and 210 from S2 to S1.

I guess I lack some skills and knowledge how to do it nicely and following best practice.

An help and advice would be greatly appreciated.

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Blue

Re: Connecting two sites

bierrrr.CC wrote:

Hi,

I've got a problem with this situation and I hope someone can help me. There are two sites (S1, S2) that have got two separate networks:

- S1 has got Cisco 6509 as a core switch and it does all the inter-vlan routing. There are vlans 10-100 and vlan 150 for management.

- S2 is much smaller, it's got 3550-12T as a core device and there are only two vlans 200, 210 and vlan 250 for management.

Those two networks are to be connected (a link between 6509 and 3550) and I'm not too sure how to do it.

I was thinking about using routing ports on each switches and adding some static routes, but I've got few issues with that.

I'd like to have all switches in one management vlan so I want to replace vlan 250 at site S2 with vlan 150.

I'd like to keep all other vlans as they are now and preferably to keep them locally at their sites.

I tried to achieve both targets using my test equipment, but I just can't make it work. If I use routing ports, I can't have one subnet for switches (same subnet at both sites). If I configure the link as trunk, then I need to move vlans 200 and 210 from S2 to S1.

I guess I lack some skills and knowledge how to do it nicely and following best practice.

An help and advice would be greatly appreciated.

You can do this with a L2 trunk. Basically you have vlan 150 at both sites for management. Then create another vlan for peering between the 2 sites eg vlan 300. Then on the trunk link between the 2 sites only allow vlan 150 and vlan 300. Finally you can either run a dynamic routing protocol such as EIGRP/OSPF or use static routes.

If you use EIGRP/OSPF then make all your vlan interfaces passive except for vlan 300 so that only vlan 300 is used to peer. If you use statics simply add static routes pointing to the other switches vlan 300 IP eg.

6500

====

int vlan 300

ip address 192.168.5.1 255.255.255.252

ip route 192.168.5.2

etc.. for each site 2 vlan

3550

====

int vlan 300

ip address 192.168.5.2 255.255.255.252

ip route 192.168.5.1

etc. for easch site 1 vlan

I would recommend running a routing protocol but it does depend on the image on your 3550.

As a side note personally  i would use L3 between the sites and have a loopback on the 3550 that you manage the switch with and route to it. Depends howm any switches you have in site 2 but a routed link would not run STP across the link and that is definitely worth considering.

Edit - just looked at attached diagram. There are multiple switches at site 2. You could have 2 management vlans one for each site and simply route between them. It's a tradeoff really but i would generally only connect sites via L2 if some servers etc. needed L2 adjacency not just for the mangament vlan of switches.

Jon

2 REPLIES
Hall of Fame Super Blue

Re: Connecting two sites

bierrrr.CC wrote:

Hi,

I've got a problem with this situation and I hope someone can help me. There are two sites (S1, S2) that have got two separate networks:

- S1 has got Cisco 6509 as a core switch and it does all the inter-vlan routing. There are vlans 10-100 and vlan 150 for management.

- S2 is much smaller, it's got 3550-12T as a core device and there are only two vlans 200, 210 and vlan 250 for management.

Those two networks are to be connected (a link between 6509 and 3550) and I'm not too sure how to do it.

I was thinking about using routing ports on each switches and adding some static routes, but I've got few issues with that.

I'd like to have all switches in one management vlan so I want to replace vlan 250 at site S2 with vlan 150.

I'd like to keep all other vlans as they are now and preferably to keep them locally at their sites.

I tried to achieve both targets using my test equipment, but I just can't make it work. If I use routing ports, I can't have one subnet for switches (same subnet at both sites). If I configure the link as trunk, then I need to move vlans 200 and 210 from S2 to S1.

I guess I lack some skills and knowledge how to do it nicely and following best practice.

An help and advice would be greatly appreciated.

You can do this with a L2 trunk. Basically you have vlan 150 at both sites for management. Then create another vlan for peering between the 2 sites eg vlan 300. Then on the trunk link between the 2 sites only allow vlan 150 and vlan 300. Finally you can either run a dynamic routing protocol such as EIGRP/OSPF or use static routes.

If you use EIGRP/OSPF then make all your vlan interfaces passive except for vlan 300 so that only vlan 300 is used to peer. If you use statics simply add static routes pointing to the other switches vlan 300 IP eg.

6500

====

int vlan 300

ip address 192.168.5.1 255.255.255.252

ip route 192.168.5.2

etc.. for each site 2 vlan

3550

====

int vlan 300

ip address 192.168.5.2 255.255.255.252

ip route 192.168.5.1

etc. for easch site 1 vlan

I would recommend running a routing protocol but it does depend on the image on your 3550.

As a side note personally  i would use L3 between the sites and have a loopback on the 3550 that you manage the switch with and route to it. Depends howm any switches you have in site 2 but a routed link would not run STP across the link and that is definitely worth considering.

Edit - just looked at attached diagram. There are multiple switches at site 2. You could have 2 management vlans one for each site and simply route between them. It's a tradeoff really but i would generally only connect sites via L2 if some servers etc. needed L2 adjacency not just for the mangament vlan of switches.

Jon

New Member

Re: Connecting two sites

Hi Jon,


Thank you for your quick reply.

I have 10 switches at the second site, should have mentioned that.

My first idea was to use L3, but then I realized I wouldn't be able to use one subnet for management. However, as you said, it's just a minor downside and you're right that I don't really want to run STP between the sites.

Thank you again!

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