How to make 2 switches talk after connecting with fiber?

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Hi

First off, I'm very new to this, so please bear with me as I'm learning. I've tried to research this but I don't know the keywords I need.

I have 2 Summit X250e-48P switches. I have managed to create a VLAN, set a DHCP scope, and connect devices. They work great individually.

I have connected them together via the SFP slots with LC connectors (labeled for use with Extreme switches).

Should that be it, or do I need to configure the SFP ports?

Sorry if I haven't given enough information.
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Adam Joseph

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Posted 7 months ago

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Nick Yakimenko

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What is the purpose of connecting two individual networks into one?
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Adam Joseph

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sorry - they are the same network. but will be in 2 different buildings.
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Eric Burke

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The only things you "may" need to do is to setup those ports as trunks to carry the multiple vlan's you setup between the switches (an assumption, based on your note about creating a vlan (there is one by default)). If you have more than one, simply add them both the each side of the link in the same fashion.  Personally, I prefer to "tag" all VLAN's in a trunk, that way it's easier to visualize the VLAN's when reading the config (when a port has an untagged vlan assigned, it's simply the default vlan for that port and is not as clearly identified).  For example, if you are connecting port 1 on the first switch to port 2 on the second switch, and you have 2 vlan's that need to be carried between the two (let's say v70 and v90), it would like like this:

SW1:
  conf default del port 1 (remove default vlan from port 1)
  conf vlan "v70" add port 1 tagged (make port 1 a tagged member of this vlan)
  conf vlan "v90" add port 1 tagged (also make that port a member of this vlan)

SW2:
  conf default del port 2 (the rest follow as above)
  conf vlan "v70" add port 2 tagged
  conf vlan "v90" add port 2 tagged

Now, those ports act like a pipeline, connecting the two switches, and adding a small amount of info to the packet header telling the opposite switch which vlan each packet belongs to.  The switches strip this "tag" when the packet enters the switch port, looks up the other members of that VLAN in its local database and then forwards the packet on to those members.  If the member is in that vlan by default (untagged), then the header is not modified as it's not needed.  If the member port is a tagged member like the pipeline was, the tag is added back before sending it to that port so it can discern which vlan it's intended for.

finally, add a description to the port to aid in documentation

SW1:
  conf port 1 display-description "TrunkToSw2P2"

SW2:
  conf port 2 display-description "TrunkToSw1P1"

BigRic
(Edited)
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Ronald Dvorak, Embassador

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And remove the DHCP scope on one of the switches because it isn't a great idea to have 2 scopes for the same network.
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Adam Joseph

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great, i'll try this out next week. Thanks!
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Adam Joseph

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OK, without any configuration, when i connect a single fiber cable it works fine. When I go through my fiber patch panel, it doesn't.


However, if I connect it to an existing switch on a different network, the link is active. All 8 fiber patch cores work fine, so that's not the issue. I find it bizarre that it will talk to my other switch, but not the one I want it to.

Is there a reason it would work over a 1m fiber cable and not a 80m cable, except for the SPF module? Because I have 6, 4 are rated 10k and the other 2 550m. And the module works fine when connecting to the switch on the other network.

Any input would be great, thanks.
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Nick Yakimenko

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you should not mess SM and MM modules,also carefully read other rates on SFP modules, especially those, who work on a single fiber (WDM)
Those who are for 550m are probably for MM fiber, 850nm wave, dual fiber
Others use TX1310/RX1550 (blue ones) and vise-versea (TX1550/RX1310nm, violet ones)

You should find out which fiber is used between fiber patch panels: singlemode or multimode
And which patchcords you use: traditionally orange are for multimode, yellow are for singlemode
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Adam Joseph

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thanks - this definitely clears a few things up for me. But it didn't solve my problem. Modules in use are 850nm and all the cables at MM. 
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Nick Yakimenko

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They are for duplex (dual) fiber? Try change tx/rx (left/right) fibers
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Adam Joseph

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they don't seem to be changeable on the patch cables i'm using. and the same patch cables are working with the other swicth on the same modules. 
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Nick Yakimenko

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fibers between patchpanels may be messed up
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Adam Joseph

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but the other switches work on them fine.

ps, thanks for all your quick replies
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EtherMAN, Embassador

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Ok one other thing you could look at is seeing what your light levels are if the optics you are using supports this.  Most modern sfp do support light readings.  

Show port 49 (or 50) transceiver info detail... if your optics supports this command you will get transmit and receive power from both sides.  It will help determine if you have any layer one issues...

output from a switch 

PLW_X430-24t_SS_W38thSt.1 # sh por 25 trans info det

Port :  25

    Media Type            : LX
    Vendor Name           : FINISAR CORP.
    Part Number           : FTRJ1319P1BTL-EX
    Serial Number         : P8S0NZ0
    Wavelength            : 1310 nm

    Temp (Celsius)            :  41.12      Status               :  Normal
          Low Warn Threshold  : -30.00      High Warn Threshold  :  93.00
          Low Alarm Threshold : -40.00      High Alarm Threshold :  110.00

    Voltage AUX-1/Vcc (Volts) :  3.31       Status               :  Normal
          Low Warn Threshold  :  2.90       High Warn Threshold  :  3.70
          Low Alarm Threshold :  2.70       High Alarm Threshold :  3.90


    Tx Power (dBm)            : -4.31       Status               :  Normal
          Low Warn Threshold  : -11.51      High Warn Threshold  : -1.00
          Low Alarm Threshold : -13.51      High Alarm Threshold :  1.00

    Rx Power (dBm)            : -6.67       Status               :  Normal
          Low Warn Threshold  : -20.00      High Warn Threshold  : -1.00
          Low Alarm Threshold : -23.97      High Alarm Threshold :  0.75

    Tx Bias Current (mA):        21.11      Status               :  Normal
          Low Warn Threshold  :  4.00       High Warn Threshold  :  70.00
          Low Alarm Threshold :  2.00       High Alarm Threshold :  80.00