Forcing a VLAN interface to be up when no devices are attached on a PC 6248

Question

I'm trying to configure a point to point connection between two 6248 switches and in setting up the VLAN interface, the interface will not come up (show ip route) unless a device is actually up in the vlan itself. This is rather annoying but I'm trying to figure out if there's a command to force the VLAN interface to be up. Thanks in advance, - Steve

Dell-Steve A · Answer

Steve,   There is no way to do this, unless a VLAN is active. Just like an individual port-the VLANs require an active port to be seen as active. You cannot force a VLAN up, but you can assign it to be carried over a port that is set to general or trunk mode-it will pick up that the VLAN interface is up and running.   Just do the following   config interface ethernet 1/g1 switch mode general switch general allowed vlan add 2-5   Let me know if you have any questions!

JarethMcKenzie · Answer

Along the lines of what SteveA was saying, if you put a trunk port connecting the switches, that will keep up the vlans because they will have a port in the vlan...it is part of the trunk...hey, that counts as a port.

saeedi · Answer

Okay, so I've tried creating both a general mode and trunking mode access between the two switches and have had no luck.

Here's a basic config rundown

switch2:
interface vlan 16
name "point-to-point"
routing
ip address 192.168.16.11 255.255.255.248
exit

interface ethernet 4/g48
switchport mode trunk
switchport trunk allowed vlan add 16
switchport trunk allowed vlan remove 1
exit

switch3:
interface vlan 16
name "point-to-point"
routing
ip address 192.168.16.13 255.255.255.248
exit

interface ethernet 1/g48
switchport mode trunk
switchport trunk allowed vlan add 16
switchport trunk allowed vlan remove 1
exit

Now, I can ping switch2 from switch3, but not the other way:

switch2#ping 192.168.16.13
Pinging 192.168.16.13 with 64 bytes of data:

----192.168.16.13 PING Statistics----
4 packets transmitted,0 packets received,100% packet loss
round-trip (ms) min/avg/max = 0.000/NaN/0.000

switch3#ping 192.168.16.11
Pinging 192.168.16.11 with 64 bytes of data:
64 bytes from 192.168.16.11: icmp_seq = 0. time=0.000 ms
64 bytes from 192.168.16.11: icmp_seq = 1. time=0.000 ms
64 bytes from 192.168.16.11: icmp_seq = 2. time=0.000 ms
64 bytes from 192.168.16.11: icmp_seq = 3. time=0.000 ms

----192.168.16.11 PING Statistics----
4 packets transmitted,4 packets received,0% packet loss
round-trip (ms) min/avg/max = 0.000/0.000/0.000

The only difference between these switches is there is another device 192.168.16.9 on switch2. I still have no seamless connectivity between these switches.

Both are running 2.0.0.12

Thanks in advance.

Message Edited by saeedi on 11-06-2007 03:47 PM

saeedi · Answer

This is driving me nuts. I finally got the VLAN up by placing a host in the same VLAN. But I still cannot ping one switch from the other. Is it even supposed to work?

I've tried trunk access, general access, and even Access access to no avail.

Any insight would be appreciated.

- Steve

Dell-Steve A · Answer

Steve,   When you ping from the switch, your ping will be sent out the VLAN interface your session is established from. So, if you ssh into VLAN 16, when you send a ping, it will be on VLAN 16 (it will route as necessary). If you telnet into VLAN 20, pings will come from VLAN 20.   If you connect from the console, you're going to be pinging from the management interface (default of 1) which is not routable-although you can define a default gateway for it.   I notice in one of them you have the port defined as 4/g48. Are these switches stacked? What does a 'sh int stat' a 'sh vlan' display?

Networking General

Was this post helpful?