Access control between VLANs on Cisco 3750 switch

I currently have a few VLANs configured on the 3750 switch (Layer 3 switch) and also have routing enabled (via ip routing). My question is, can I use access-list commands to control access between VLANs? (Does this switch even support this type of setup?)


PS: There is one VLAN that I'd like to isolate from the rest of the other VLANs


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As far as i know it is only possible by applying VLAN Access maps

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Leander de Graaf

You can use VACL for VLAN access .elow is some thing which is in CCNP prepration for PVLAN

The set security acl Command The set security acl command is used to create VLAN access control lists (VACLs). VACLs allow you to filter upon Layer 3 and Layer 4 parameters and are applied for all inbound access on the entire VLAN. Although very similar to router ACLs, VACLs can be applied only in the inbound direction and can also filter traffic switched within a VLAN. The following tasks are required to configure VACLs:

Create the VACL

Commit the VACL to hardware

Apply the VACL to a VLAN

To create a VACL for IP traffic, you use the set security acl ip command:

set security acl ip acl-name {permit | deny} {ip | tcp | udp} source destination

Rate if help

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I'd recommend the 3750 Switch Software Configuration Guide's chapter on Network Security with ACLs:

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VACLs are usually used to control traffic within a VLAN (Host A in VLAN 10 to Host B in VLAN 10), but can be used to filter on layer 2 or layer 3. A VACL is applied to all traffic in both directions so creating access-list logic can be more challenging but VACL's can povide a high level of security.

Router ACL's are easier to manage for filtering traffic between VLANs (Host A on VLAN 10 to Host B on VLAN 20). Router ACL's can be applied in inbound and outbound directions and are very similar to ACL's applied to interfaces on any Cisco router. In a VLAN environment, you apply the ACL to switch virtual interfaces (SVIs) or routed interfaces (no switchport).

Here's an example:

Switch(config)# access-list 110 permit tcp any gt 1023 Switch(config)# access-list 110 permit tcp any host eq 25 Switch(config)# access-list 110 permit icmp any any

Switch(config)# interface VLAN 10 Switch(config-if)# ip access-group 110 in

3750 switches handle most ACL filtering in hardware so these switches can handle a fairly large number of access-list statements with little impact on performance.
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I never denied Access-list are not a solution but for VACL are more secure.

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I squirm when I see people treating the routing on a layer 3 capable switch as a switch instead of a router. A layer 3 switch has the capabilities of a router and its routing processes should be treated as those of a router.

Do not use a VACL. Use the normal access-list methods that you learned for a router and apply the access-list to the VLAN interfaces.


interface vlan 1 ip address ip access-group BAN_VLAN_2 in ! interface vlan 2 ip address ! interface vlan 3 ip address ip access-group BAN_VLAN_2 in ! ip access-list extended BAN_VLAN_2 deny ip any permit ip any any

Reply to
Scott Perry

Thank you all for the suggestions and recommendations. Since Scott's method seems simple enough, I will try that first and post back with my finding...

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