asked on

Switch and Routing,

Good day,

assistance with routing.

i have a L3 Catalyst Switch acting as the core switch with 2 svi, one VLAN 4 (192.168.201.250 (Data) and VLAN 30 (192.168.30.250(WiFi). I have configured an access port on port 1 for VLAN 30 and configured a route to an internet gateway (192.168.201.2).

in the internet gateway i have a route that goes back to the Catalytst Switch.

Internet Gateway Route ----------- Source (ANY) Destination (Wifi(192.168.30.1/24) Service (ANY) Gateway (WiFi SVI (192.168.30.250) Interface (LAN)

with the route i am able to get out to the internet fine, but, i am able to access VLAN 4 devices? once i remove the route i am unable to access the internet or the VLAN4 devices. So i think i may have the route wrong.

Internet Gateway (192.168.201.2) --------->L3 Switch (192.168.201.250) ----------->VLAN4 and VLAN30
(192.168.30.250)

Predrag Jovic

Yes, you need to have route to point to L3 switch as next hop to reach 192.168.201.0/24 & 192.168.30.0/24 networks if your Internet Gateway is router.

How routers work (L3 switch do this the same way):
To forward traffic
1. router checks routing table to find best match (most specific route)
2. - if matching route is found - forward traffic according to best match route
(default route is the least specific route - every traffic matches at least to default route)
- if matching route is not found (default route is not configured) - drop traffic

If router don't have other route to destination (learned statically or dynamically) that is more specific than default route - traffic will be forwarded using default route (most likely in your case this mean that traffic would go back to internet).

So, most likely, if you don't assign those route(s) traffic will be forwarded back to internet.

What I would do differently
- if switch support option - I would convert port to L3 port and attach Internet Gateway to that port
- if L3 port is not option then I would create separate VLAN for this purpose
So, there would be 3 VLANs total and internet gateway still need to have route(s) that point to L3 switch as next hop to reach Data and WiFi networks.

IBSIT

ASKER

my internet gateway is my firewall.

Predrag Jovic

If firewall has routing table, that's it, the same rules apply.

IBSIT

ASKER

Can you give me an example:

Source (ANY) Destination (Wifi(192.168.30.1/24) Service (ANY) Gateway (WiFi SVI (192.168.30.250) Interface (LAN)

currently what I have?

SOLUTION

Predrag Jovic

membership

Create a free account to see this answer

Signing up is free and takes 30 seconds. No credit card required.

See answer

IBSIT

ASKER

ok I change the gateway to the 201.250 and I am still pinging vlan 4 devices from vlan 30

ASKER CERTIFIED SOLUTION

Predrag Jovic

membership

Create a free account to see this answer

Signing up is free and takes 30 seconds. No credit card required.

See answer