Cisco SG-300 Out Smarted By Smartport

The More You Know

Let me preface this post with, I should RTFM and saved myself some time. I want to give some encouragement to anyone reading this. If you’re just starting out in IT or still struggling to learn something, understand, nobody knows everything. Social media like to portray how easy everything is. What’s hidden is all the struggles leading up to the content.

The Objective

I’ve been looking for a more energy-efficient network switch that is a bit quieter. Until yesterday the main switch in my home lab was a Juniper EX4200-24t. The 4200 is a great switch packed with many features out of the box. I purchased it for $70 shipped about 5 years ago off eBay. The 4200 is hungry, using around 200 watts sitting in the rack. It is also incredibly loud. So much so that you would think I’m keeping a jet engine on idle in my office. It does add a white noise effect to the entire house - if you’re looking for that.

The replacement is an eBay special Cisco SG-300-52P for $80 shipped. This is part of Cisco’s line of small business or prosumer equipment. If memory serves, this product line was born from the Linksys SGE products Cisco purchased in 2003. Cisco’s current model is the CBS350-48P-4G or the CBS350-48P-4X.

You might ask, why did you pick that switch? You could have used “insert option here”. I’m sure, that’s true. The day I clicked buy, this switch was inexpensive. I’ve deployed the older SG-200 without POE several times, so I was somewhat familiar with the product line. I know how to modify the switch for dual power, swap the fans, etc. I have parts for most it on hand too.

The Problem

I started this project late at night. I was tired and should have just gone to bed. Also, because of my prior experience with similar models, I began with some misconceptions and expectations. The short of it is, I didn’t read the docs, I got frustrated, I clicked things, I got more frustrated, I clicked more things… You see where this is going.

My config is a quick script in my old switch, it’s specific, but isn’t complicated. To complicate things the web interface on this switch is maddeningly slow. Page load times can be 5 seconds. If you’re only spending a few minutes in the config fine. 15-20 minutes later, you start to wonder if pouring a case of Red Bull on it might speed things up. This slowness drove my frustration.

The SG-300’s default config isn’t for someone like me. T designers had a normal small office environment in mind. Bob in Sales and Sally in Accounting can plug this box in and it just works. It wants to help you.

My Configs

Looking at an example Juniper config from my switch. Four total VLANs, one is voice, and three for data, LLDP-MED tells the phones to use 17 VLAN for the voice VLAN.

set vlans data-vlan vlan-id 255
set vlans voice-vlan vlan-id 17
set vlans data-vlan interface ge-0/0/0.0
set interfaces ge-0/0/0 unit 0 family ethernet-switching vlan members data-vlan
set interfaces ge-0/0/0 unit 0 family ethernet-switching port-mode access
set ethernet-switching-options voip interface ge-0/0/0.0 vlan voice-vlan
set ethernet-switching-options voip interface ge-0/0/0.0 forwarding-class assured-forwarding
set protocols lldp-med interface ge-0/0/0.0

set vlans data1-vlan vlan-id 254

set vlans data1-vlan interface ge-0/0/1.0
set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan members data1-vlan
set interfaces ge-0/0/1 unit 0 family ethernet-switching port-mode access
set ethernet-switching-options voip interface ge-0/0/1.0 vlan voice-vlan
set ethernet-switching-options voip interface ge-0/0/1.0 forwarding-class assured-forwarding
set protocols lldp-med interface ge-0/0/1.0

set vlans data2-vlan vlan-id 253

set vlans data2-vlan interface ge-0/0/2.0
set interfaces ge-0/0/2 unit 0 family ethernet-switching vlan members data2-vlan
set interfaces ge-0/0/2 unit 0 family ethernet-switching port-mode access
set ethernet-switching-options voip interface ge-0/0/2.0 vlan voice-vlan
set ethernet-switching-options voip interface ge-0/0/2.0 forwarding-class assured-forwarding
set protocols lldp-med interface ge-0/0/2.0

I plugged in, upgraded the firmware, and set off configuring my interfaces.

I want to take a second and give a shout-out to VanDyke Software’s SecureCRT. It has built-in file transfer capability, including a TFTP Server. I’ve been using SecureCRT and SecureFX for well more than a decade.

SG-300’s Config

What I thought I was trying to deploy.

vlan 255
name data-vlan
vlan 17
name voice-vlan
interface GigabitEthernet1
switchport mode access
switchport access vlan 255
switchport voice vlan 17

I know this model supports voice VLANs. Let’s go to the CLI.

switch3a68d4(config)#int GigabitEthernet1
switch3a68d4(config-if)#voice vlan 17
% Unrecognized command
switch3a68d4(config-if)#voice vlan
  cos                  Class of service.
  enable               Voice VLAN enable on interface.
switch3a68d4(config-if)#voice vlan enable
   <CR>
switch3a68d4(config-if)#voice vlan enable
Voice VLAN State is not OUI-enabled.

Oof. Back to the web interface, maybe I need to turn something on.

Clicking around, very slowly, I can’t find these OUI settings.

Whatever, I’ll build trunks and set LLDP. It’s 10:30 PM and I want to go to bed.

interface gigabitethernet1
 switchport trunk allowed vlan add 17
 switchport trunk native vlan 255

Can’t see how to set a policy. Maybe it is already set when I configure the voice VLAN globally? I see Voice VLAN is set for 17. Maybe I should RTFM. Nah, send it.

I rack the switch. Plug in my laptop and the data VLAN defaults to 1 on half of my ports??? Voice VLAN is 17 on everything with a phone though.

Maybe I didn’t save? Set the configs again.

It did it again, changed data VLAN to 1.

Either I’m crazy or this switch does whatever it wants. I set all the things once more. Again, I thought I did something wrong. I pay attention this time.

I’m not CrAzY. Once more, the switch changed my data VLAN to 1.

Smartport Enters The Chat

After clicking around I find that Smartport is on. Smartport actually laughing at me. Telling its macro friends what a dork I am. More clicking, I find we’re running a macro that is enabled by default. The macro picked up my voice VLAN but left the data as 1, the default native VLAN. I don’t even use VLAN 1.

I can’t use a macro, I have multiple data VLANs depending on what I’m doing.

A sample of what I ended up with. I disabled auto things.

vlan 255
name data-vlan
vlan 17
name voice-vlan

no lldp med network-policy voice auto
lldp med network-policy 1 voice vlan 17 vlan-type tagged up 5 dscp 46

voice vlan id 17
voice vlan state disabled
macro auto disabled
macro auto processing type ip_phone_desktop disabled
macro auto processing type switch disabled
macro auto processing type ap disabled

interface gigabitethernet1
 switchport trunk allowed vlan add 17
 switchport trunk native vlan 255
 lldp med network-policy add 1

Few Setting Screens

Conclusion

By default Smartport the will override static port configurations, auto-apply policies, and run macros. The issue is, my network has some unique labby configurations that don’t script very easily. Some features that were giving me trouble:

• Auto Smartport - uses macros to dynamically configure ports based on what you plug in.
• Auto Voice VLAN - discovers the voice VLAN from other sources and synchronizes it.
• Telephony OUI - When matching traffic is received, the port is added to the voice VLAN.

Some of these features work together, and some operate interdependently depending on the switch and individual port configurations. Cisco’s default policy is, the switch should assign any phone to the voice VLAN, 17, and leave the native VLAN, 1 by default. If another switch is already configured the new switch should learn the config from the existing environment.

I don’t like auto-policies overriding static configurations. I understand why someone might want that though.