Switch to Switch ( L3) - Connection Solutions

[machine23]

Hi All , 

I have 2 separate networks each with Core switches , say network 10 and network 192 and wish to connect the 2 networks and also the relevant vlans with 2 cables running from one to the other for a little bit of resilience but it isn't that pressing to have any fault tolerance. 

Network 10 is running VTP, So just wondering what is the best method and practices to attain this.

thanks 

[MHM Cisco World]

two separate network and then you specify two VLAN, can you more elaborate ?

[machine23]

Hi I mean make sure the vlan and both networks can talk to each other but I can do that by allowing specific vlan..

[MHM Cisco World]

the VLAN can connect to each other in both SW through the trunk if you allow VLAN and use same native VLAN 
BUT 

here since you use VTP in one side I prefer use VTP transparent or make sure the config of VTP is correct in both SW before interconnect. 
the VTP effect VLAN in DB and effect VLAN allow in trunk through pruning  

[Reza Sharifi]

Hi,

Since each network has its own vlan/subnet, you can simply use a /30 to connect the 2 networks together. If you are looking to add fault tolerance, you can use multiple physical links e.g., 2 cables with 2 /30s, or use the same 2 physical links and put them in an L3 Portchannel with 1 /30. Using this solution, it does not matter if one side is using VTP and the other side is not.

HTH

[machine23]

As I will be doing this on production I just want to be completely sure - so I have the config as below. I have not connected yet.

shouldn't this be a trunk  and not an access port like the below ? and what else am i missing ?

Ive got a /30 SVI on vlan 88  ON  on vlan 88 on SW1 and SW2

SW1 Config:

interface Port-channel45
switchport access vlan 14
switchport mode access
end

interface GigabitEthernet2/0/11-12
switchport access vlan 14
switchport mode access
channel-group 45 mode on

SW2 Config:

interface Port-channel45
switchport mode access

interface GigabitEthernet2/0/11-12
switchport mode access
channel-group 45 mode on

[Reza Sharifi]

It should be an access port because all you need is a transit vlan, which in your case is 14. You also need an SVI on each switch and since you are using a vlan to connect these 2 networks together, it does not have to be a /30. It could be a /29, 28, etc..

Also, on switch-2, make sure you specify vlan 14 as below.

SW2 Config:

interface Port-channel45
switchport mode access

switchport access vlan 14

[machine23]

Ok will try that thanks for your input also this wont cause any storm will it?

[Reza Sharifi]

Ok will try that thanks for your input also this wont cause any storm will it?

Should not.

Also, before you start adding any static routes, make sure your physical interfaces are up, PO is up, and you can ping from one switch to the other and vice versa, link failover works. Static routes should be the last part and then you can test end-to-end.

Don't forget to do all this work in a maintenance window in case something unexpectedly goes wrong.

HTH

[MHM Cisco World]

One Q' are vlan in both SW is same ?

If same then config trunk and allow all vlan 

If not then use access port and SVI in each SW and you need static route in each SW for vlan in other SW.

**SVI for transit vlan' this vlan must add to both SW

[machine23]

The vlans are different on both switch. 

thanks again 

[machine23]

So basically I want to connect sw1 and sw2 and make sure the clients in both subnets can ping and access each other… just put up a picture for ref…thanks again 

[MHM Cisco World]

use access port and SVI in each SW and you need static route in each SW for vlan in other SW.

**SVI for transit vlan' this vlan must add to both SW

This solution so what you need.

[machine23]

Ok so one switch will have svi 192.168.77.1 and other switch svi 192.168.77.2 ? Thanks

[MHM Cisco World]

Yes SVI of vlanX which use only to interconnect both l3sw.

Now you need static route 

Ip route <subnet of SW1> svi ip of SW2 

Ip route <subnet of SW2> svi ip of SW1