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Unable to connect a SF300 to a Catalyst 3750


I realize this has been dealt with several times and i have reviewed every article and researched this until its causing sleepless nights but i can't even get them to talk to each other. Granted, I'm a rookie and thought i could figure this out but after 3 straight weeks of brain busting all I've accomplished is a huge waste of time.

I inherited this and lets just say that based on past findings of predecessor projects I have reason to suspect anything and everything he touched to be.... 'not up to normal standards'


SF300 has been wiped and is not in production so I can do anything i wish to it. 3750 is not only in production but appears to be the core switch handling 5 VLANS, of which 2 of them I am no longer using. Goal is for sf300 to handle two VLANs via ports GE1 and/or GE2 and trunk to the 3750 port fa6/0/47. VLAN10 ( for data and VALN150 ( for VOIP. VLAN80 appears to be the native VLAN in the mix, VLAN1 is present but in different states of configuration depending on the switch being viewed. There are 4 other switches involved so while I can't make global changes to the 3750 that might impact other switches I can choose one port to do what I wish with.


That being said, here's port 47 of the catalyst 3750:


SW1#show run int fa6/0/47
Building configuration...

Current configuration : 167 bytes
interface FastEthernet6/0/47
switchport trunk encapsulation dot1q
switchport trunk native vlan 80
switchport trunk allowed vlan 1-150
switchport mode trunk



SW1#show spanning-tree int fa6/0/47

Vlan Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- -------
VLAN0001 Root FWD 19 128.321 P2p
VLAN0010 Desg FWD 19 128.321 P2p
VLAN0020 Desg FWD 19 128.321 P2p
VLAN0080 Desg FWD 19 128.321 P2p
VLAN0150 Desg FWD 19 128.321 P2p


---- -------------------------------- --------- -------------------------------
1 default active Fa6/0/2, Fa6/0/3, Fa6/0/4, Fa6/0/5
Fa6/0/6, Fa6/0/7, Fa6/0/8, Fa6/0/9
Fa6/0/10, Fa6/0/11, Fa6/0/12, Fa6/0/13
Fa6/0/14, Fa6/0/15, Fa6/0/16, Fa6/0/45
Gi6/0/1, Gi6/0/2, Gi6/0/3, Gi6/0/4
10 ops active Fa6/0/17, Fa6/0/18, Fa6/0/19, Fa6/0/20
Fa6/0/21, Fa6/0/22, Fa6/0/23, Fa6/0/24
Fa6/0/25, Fa6/0/26, Fa6/0/28
20 VLAN0020 active Fa6/0/29, Fa6/0/30, Fa6/0/31, Fa6/0/32
80 native active
150 VLAN0150 active Fa6/0/43, Fa6/0/44, Fa6/0/46, Fa6/0/48
160 VLAN0160 active Fa6/0/39, Fa6/0/40, Fa6/0/41, Fa6/0/42
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup


here's the sf300, attached.




I have no ego that needs feeding so if anybody sees anything at all out of whack or odd or just plain wrong pls tell me. I know the ports should be access but until I can figure out how to get started I simply tried to open everything up.


also, i can talk to the switch 3750 if I plug it into one of its access access ports but I think that would defeat the purpose of using VLANS..? I am so baffled that I don't even know how he got anything to work altho I do see native VLAN mismatches in the other switches connected. Traffic does pass thru them, tho, so I shouldn't criticize as I can't get anything to work.


drowning in a sea of tears of frustration....


any additional info at all you might need , pls ask. and pls don't assume knowledge of where none exists so when giving instructions pls keep that in mind. and This may be a puzzle to you as nothing i've seen yet leads me to believe things have been done corectly


Rising star

Re: Unable to connect a SF300 to a Catalyst 3750

i read it on other post

" You can do this by setting the 3750 for 802.1Q ecapsulation on the trunk port, set the native vlan, and allow VLAN's accross. On the SF300 you would perform the same process create the trunk port, allow the VLAN's, and set the PVID to match the native VLAN on the Trunk interface of the 3750. In order to do this you will need your VLAN's pre-configured on both switches. Hope this helps you out."

look it:
Jaderson Pessoa
*** Rate All Helpful Responses ***

Re: Unable to connect a SF300 to a Catalyst 3750

Thx for getting back to me. I saw that article earlier but double checked that everything matched and still no ping/traffic. Does the native VLAN need the IP declared on the sf300? Using same address as what is declared on the 3750?
Rising star

Re: Unable to connect a SF300 to a Catalyst 3750

i cant see your vlan native 80 create as well on your SF300

vlan database
vlan 1,10,150

Jaderson Pessoa
*** Rate All Helpful Responses ***
VIP Advisor

Re: Unable to connect a SF300 to a Catalyst 3750


Basically the configuration of this SF300 would simply to make it become a host switch and only that is required for inter vlan communication would be a trunk link, which could either be a single link or two separate physical or a aggregation trunk links ( dual links equaling one virtual connection) to the core.

If you wanted for remote management reachability then an additional mgt vlan interface and default-gateway would be needed.


Native vlans are link based not switch based so in theory you could have a different native vlan for different switch interconnects but it is not really recommended to do this so I would suggest to apply the same native vlan  on the interconnect(s) between 3750 and the SF300


Would be easier if you posted the config of the core switch and maybe a small diagram of you network, So we can provide you with a viable solution, but as i have stated usually only what would be required is a simple trunk link and correct vlans defined in its database on this switch to work accordingly.


kind regards

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future

Re: Unable to connect a SF300 to a Catalyst 3750

Thx much for all replies. 


Here is run config for both.  the 3750 is apparently the core switch with multiple vlans and all other switches are simply dedicated to a single VLAN, then connecting to the core 3750.  One switch is dedicated to VLAN80, one to VLAN10, one to VLAN150 et al.


The fa6/0/1 port goes to the outbound router, all other ports service either devices or inputs from other switches. 

I'm trying to configure port fa6/0/47 to go to the GE1 port on the SF300.


My predecessor apparently couldn't get trunking to work well as switches communicate via access ports.  There are 2 Catalyst 3750's and four SF300's.  Native mismatch errors abound but don't show in the SF300 gui's, only in telnet do i see them pop up.

The access list ion the 3750 I added to prevent guest wifi VLAN/network from communicating with internal devices and is my only contribution to that mess.


The ultimate goal is to consolidate down to 3 switches and have all switches communicate via trunks with tagged VLANS. And whenever possible, use the gig ports for switch to switch communication. (the 3750 does not have gig ports).  Once upper mgt sees the value on improving the network due to increased stability and performance I can set a strategy for upgrading switches, etc but for now, I work with what I have.  My idea is that once i have one trunk port working and better understand the mechanics for putting that in place I can duplicate it on the other SF300's, then consolidate.  The two challenges I have is that everything is in production and mgmt. is unforgiving of any disruptions, big or small, and my skills are not sufficient to wipe them and put it back together again correctly in a reasonable amount of time.


Pls review and feel free to tell it like it is and make suggestions for improvement/refinement as well.  I haven't personally touched a switch in 20 years so while I am learning rapidly, there are gaping holes in my knowledge and all recommendations highly appreciated.


thx again.....




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