04-23-2012 09:02 AM - edited 03-07-2019 06:17 AM
On a current Catalyst product Is it better to assign an IP address directly to a VLAN interface or to assign an IP address to a Loopback interface that is in a particular VLAN? What are the benefits or pitfalls of either method?
Solved! Go to Solution.
04-23-2012 10:03 AM
Hi ,
You cannot configure the loopback interface as switchport. Also you cannot configure a SVI ( interface vlan ) as a switchport. So the solution is to configure the IPs on the interface vlan.
Dan
04-23-2012 09:42 AM
Not sure what you mean by a loopback address in a given vlan. Generally you would have a single loopback for a given L3 device and this is used by any dynamic routing protocols like ospf or eigrp as this interface is always in a up/up state .
04-23-2012 09:56 AM
What I mean by that is creating a loopback interface and placing it in the particular VLAN as opposed to assigning the VLAN interface an IP address directly. So, for example, let's take a Catalyst 6506. If I'm hosting three VLANs 10-12 that need IP addresses (default routes for three different networks) I would potentially have three loopback interfaces with an IP address (one in each subnet consumed by those VLANs). The alternative is to instead assign the VLAN interfaces the IP addresses and not mess with loopback interfaces.
So lets give an example. Normally I just assign addresses to the VLANs thusly:
int vlan10
description Fiscal
ip address 10.10.10.1
int vlan11
description IT
ip address 10.10.11.1
int vlan12
description Maintenance
ip address 10.10.12.1
I'm asking if it's good, bad, or indifferent to use loopback interfaces instead:
int vlan10
description Fiscal
no ip address
int vlan11
description IT
no ip address
int vlan12
description Maintenance
no ip address
int lo10
switchport
switchport access vlan 10
switchport mode access
ip address 10.10.10.1
int lo11
switchport
switchport access vlan 11
switchport mode access
ip address 10.10.11.1
int lo12
switchport
switchport access vlan 12
switchport mode access
ip address 10.10.12.1
04-23-2012 10:03 AM
Hi ,
You cannot configure the loopback interface as switchport. Also you cannot configure a SVI ( interface vlan ) as a switchport. So the solution is to configure the IPs on the interface vlan.
Dan
04-23-2012 10:10 AM
Thanks!
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide