Conflict with Cisco SG200-26 Managed Switch

[electrosuperman]

908e-26/sco SG200-26/
Hello,

In my Lan network, I have two Adtran PoE switchs for our VOIP. Switch # 7100 and Switch # 1234 and a 908e router being feed from our incoming T1's.  All VOIP adtran phones are wired to these two switchs in our main complex. I have another building ajacent to our main complex that has only 6 VOIP phones and 6 PC's...From the Adtran switch, one port feeds the remote building which is tied to a Cisco non-PoE SG200-26 switch.. From the ports of this switch, it feeds the six VOIP phones and the PC's.  The VOIP phones at this location use individual power supplies for power.

The question comes into play, we have had a utility power outage, when power was restored, these six phones would not operate. It seems that the Cisco switch prevents something from passing to the Adtran switchs for startup. If I remove the Cisco switch from this building and replace it with a unmanaged type switch, the phones will startup and operate.  The existing Cisco switch is operating in its default mode. No programming has been done to this switch.

Any help with this Cisco issue ????

Thankyou in advance

Electrosuperman

[Anonymous]

electrosuperman,

Thank you for posting this question.  There are many things that happen when a phone boots up.  First the phones will send out a DHCP request.  When they get a response they are also expecting a DHCP option to specify the server where they need to download files among other information (VLAN, username/password, etc).  Assuming the NetVanta 7100 is acting as the DHCP server for the network (PCs and phones)  my best guess is either the DHCP requests are no longer making it to the 7100 with this switch in place, or they are but the phones lose connectivity when changing VLANs.  If replacing the switch resolves the issue, it appears either it is malfunctioning or there is a configuration difference between it and the replacement.  It could be that the switch reverted to a previous configuration when it lost power.  I would suggest checking the switch configuration to make sure nothing is set incorrectly within it, and possibly try defaulting it and re-configuring it.

Thanks,

Matt

[Anonymous · Accepted solution]

electrosuperman,

    Make sure the ports the phones and the uplink port are Trunk mode allowing the data vlan and the voice vlan. It sounds like the switch ports maybe in access mode and therefore not passing the voice vlan traffic.

John Wable

[electrosuperman]

Yes, Trunk mode had to be enabled to make it work. Vlans were all on 1 which was fine,,,Will now split them up so the Data and VIOP are different. The book on the switch stated "Smart Switch" and would trunk automatically...Guess not !!!

Thanks

[Anonymous]

electrosuperman,

    The Cisco smart ports only work correctly when the phones are Cisco phones, they use a special version of the LLDP proprietary to them to set the VLAN of voice, it works in conjunction with CDP.  I always disable all the auto functions on those switches as I have had cases where out of no where they automatically make changes to VLANs when a new device is plugged in.

John Wable