When creating VLANs for just L2 on a switch -- routing will be handled by a device within that VLAN such as a load-balancer -- it isn't necessary to create the vlan interface. As a matter of habit, I always create the interface anyway-- no IP address - so I get all the interface bits and packet stats in "sh interface".
Are there any negatives to what I think is a best practice to just create the L2 interface?
When do you create or not create the interface for a L2 VLAN?
I am looking for answers that discuss only L2 VLANs, not the merits and use cases for L3 VLAN SVIs.
Cisco reports a L2 interface as EtherSVI on my 6500 -- no IP address. Is it correct or incorrect to still think of a L2 interface as an SVI though the we all know the usual use-case is to have an IP address for routing? The question is only about whether or not I should have this L2 interface in the first place. You can see only the L2 counters are incremented, but still giving some value.
s-oc4-n2-agg1#sh int vl281 Vlan281 is up, line protocol is up Hardware is EtherSVI, address is 0019.a925.2000 (bia 0019.a925.2000) Description: svi.SLB-FE-Web-Servers MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive not supported ARP type: ARPA, ARP Timeout 04:00:00 Last input 00:00:02, output 00:00:10, output hang never Last clearing of "show interface" counters 1d12h Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/40 (size/max) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec L2 Switched: ucast: 1138722618 pkt, 1070173012274 bytes - mcast: 76471 pkt, 8482399 bytes L3 in Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes mcast L3 out Switched: ucast: 0 pkt, 0 bytes mcast: 0 pkt, 0 bytes 74604 packets input, 8350307 bytes, 0 no buffer Received 74604 broadcasts (0 IP multicasts) 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 218 packets output, 17658 bytes, 0 underruns 0 output errors, 0 interface resets 0 output buffer failures, 0 output buffers swapped out