best practice for connecting core switch to ISR Internet/VOIP router

[adeebtaqui]

Kindly advise what is the best way to connect a layer 3 core switch like cisco 9500 or aruba 5400 to cisco 4451 deployed as internet&voip router.

Should i configure the interlink on core switch side as trunk allowing all vlans with mgmt as native and on router configure SVI for all vlans that need communication from core switch?

Or should I create a access layer port in mgmt vlan on core switch side and on router side side layer 3 port belonging to subnet of mgmt vlan.

[M02@rt37]

Hello @adeebtaqui,

You router is your CME? Voice Gateway?

Since you have L3 Core with Gateways of each Vlan, I will do a routed link between L3 Core and the VoiP Router. 

From the Core a default route pointing Router Interface ; on the Router static routes to go to your different LANs towards Core interface. 

[Giuseppe Larosa]

Hello @adeebtaqui ,

>> the best way to connect a layer 3 core switch like cisco 9500 or aruba 5400 to cisco 4451 deployed as internet&voip router.

I see two options :

a) a single routed L3 link as explained by M02@rt37 

b)  to keep separated internet access from VOIP you can use two distinct L3 links that can be logical (subinterfaces on router side + L2 trunk and two dedicated SVIs on core switch side) or two different L3 router ports. There is an advantage in security as you can better control communications . This can be combined with the usage of a dedicated VRF for all VOIP related subnets / SVIs on the core switch side.

Hope to help

Giuseppe