Hello,
When you need a routed interface then you use SVI. Let's say you want 30 ports on a switch that need to be connected to User ports (Vlan 10) and 10 ports to servers (Vlan 20). Now you want these two segments (DATA and server vlan) to talk to each other, so you need to enable routing there. That can be achieved by creating an SVI for Vlan 10 and Vlan20, the hosts in respective Vlan will use SVI's IP as their default gateway.
In older days, we used to do Router on a stick kind of design but that's a bottleneck. It is much efficient to have SVIs on your L3 switch itself.
Now coming to your problem- Phones are not getting an IP address.
so who is configured as DHCP server for Voice vlan(10), your switch? If so then definitely the switch should have an SVI for Vlan10, it should have an IP address.
Scenario-1
Here is a sample config that you might need on switch in case you want the L3 switch itself to act as DHCP server for voice vlan.
Example-
service dhcp
!
interface vlan 10
ip address 10.192.10.1 255.255.255.0
no shut
!
ip dhcp pool VOICE-POOL
network 10.192.10.0 255.255.255.0
default-router 10.192.10.1
dns-server <as needed IP>
!
ip dhcp excluded-address 10.192.10.1
!
!
Scenario-2
=============
If the switch is not acting as DHCP server and some windows server then you can configure the switch as relay agent .
service dhcp
!
interface vlan10
ip address 10.192.10.1
ip helper-address <DHCP server IP , could be an IP from different vlan>
!
Note- you should have IP reachability to DHCP server from your switch with source of Vlan10 IP.
!
Please rate the post if helpful.
Regards,
Kallol
