Routing and switching

[Network Pro]

Hi,

L3 switch (routing) -----  ISP (private MPLS) ----- L2 switch (2960 - Main Comms Room) ---L3 Switch (3750) (satelite cab)

I have a question regarding the above design and to implement this.  We have a l3 switch and another office to connect. But due to few problems we cant install the 3750 in the Main Comms Room and has to be terminated in sat cab. My question would there be any way i can install a 2960 (L2 switch) and connect the WAN circuit on the l2 switch but use the l3 for routing ?

Basically i want l2 switch as passthrough for wan traffic but manage it internally also

Hope its clear ?

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

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In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

If your "WAN" media is Ethernet, sure you can pass the traffic through a L2 switch.  As you're using a VLAN capable switch, I would suggest dedicating a VLAN for the transit traffic.

[Network Pro]

so do you mean to say to use vlans between 2960 and 3750 and just trunk them and use the routing on 3750 ? and to manage the 2960 use different set of vlans with SVI and manage from 3750 ?

[Jon Marshall]

Is the MPLS network a L2 or L3 service ?

Jon

[Network Pro]

@john - mpls is layer 3

@JosephDoherty      - i am thinking of doing it this way - please correct me if i am wrong.

Make the port on 2960 where the WAN circuit terminates as access vlan 100 and make another port on the same 2960 as vlan 100 and connect to 3750 on a port (Access vlan 100) and create svi vlan 100 with a layer 3 address.

Now for management of the 2960 create another cable between 2960 and 3750 and make it as l3 port or layer 2 port (if l2 port then dont allow vlan 100 alone) - will this work or any other simpler way ?

Thanks

[Jon Marshall]

If you want to manage the 2960 internally from that site then you can do as you suggest and it work fine ie. all routing to another site is done via vlan 100.

So assuming vlan 100 is used for routing to remote locations you have a number of choices for management of the switch -

1) use a separate physical connection as you suggest

2) create an SVI in vlan 100 on the 2960 purely for management. It it usually recommended to have a separate vlan for managing switches though and if you want vlan 100 to be used only for routing to and from the site it may be better not to reuse that vlan for also managing the switches.

3) have a new unused vlan for managing the switches. Make the connection between the 2960 and the 3750 a trunk link that allows vlan 100 plus the management vlan only. If you did this you would also need an SVI for the management vlan on the 3750 and the default gateway on the 2960 would be the L3 SVI IP address on the 3750 for the management vlan.

Personally i have pretty much always used option 3) but the others are valid and in the end it is really up to you as to which you choose.

Jon

[Network Pro]

Thanks Jon, i like option 3 which is pretty close to what i thought as well.

i have raised this question in another area of the same forum but thought will ask you as well.

I am thinking of replacing hte Cisco 3750 with a Cisco 3850 which has a inbuilt WLC.

Does the cisco 3850 wlc at a branch site join to our mobility group at our Main site instead of having it as a standalone WLC

also does AP's need to be connected directly to 3850 to get registered ?

[Jon Marshall]

Sorry but can't help you with the Wireless questions as that really isn't an area i have much experience in.

Jon

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

No, I just mean that the transit traffic, on the 2960, should probably have its own VLAN.  That alone doesn't mean you need to trunk between the 2960 and 3750, but if there's other VLANs on the 2960 that the 3750 needs to work with, then you may want a trunk between them and the transit VLAN might be on that trunk (might not too, i.e. you might want a dedicated link for that transit traffic).