why two vlans on same switch need no routing

hahacc · 01-07-2016, 08:29 PM

Hi Folks,
Today I saw one comment below:

Code:

 vlan 124 and vlan 126 are on same distro switch and need no routing, those are self connected interface on z2-rtr-1/2.

So it meant if two vlans are on the same switch, then no routing is needed for communication between them. I'm not sure how this works, is there any commands on cisco routers/switches that control this behavior?

Thanks in advance!

Elizine · 01-07-2016, 11:34 PM

You can use Policy Based Routing which CAN forcefully send all the traffic coming reaching the vlan interfaces.

Eg:

10.170.10.10 is the Gateway ip

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Quote:

access-list 100 permit ip 192.168.1.0 0.0.0.255 any

access-list 110 permit ip 172.16.1.0 0.0.0.255 any

route-map vlan500 permit 10

match ip address 100

set ip next-hop 10.170.10.10

route-map vlan600 permit 10

match ip address 110

set ip next-hop 10.170.10.10

int vlan 500

ip address 192.168.1.1 255.255.255.0

ip policy route-map vlan500

int vlan 600

ip address 172.16.1.1 255.255.255.0

ip policy route-map vlan600

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nini09 · 01-08-2016, 02:50 PM

In general, traffic between two VLAN interfaces need a route. But some product support bridge, it forward packet based on MAC address only, no VLAN. In this case, no route is requested.