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Update topology to L3 disruptive?

  • 30 March 2020
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Hi,

Very quick question. I’ve got to make a change to a topology to use L3. Predominantly because we are also going to use that same topology for a new internal captive portal.

Example below:

 

That topology is already in use on another SSID.

Questions is, will making this L3 and applying an IP address cause any disruption?

Many thanks in advance.

 

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Best answer by Miguel-Angel RODRIGUEZ-GARCIA 30 March 2020, 21:59

Martin,

 

Doing so, you’ll add a L3 interface to your EWC.

Possible impacts are:

  • routing traffic that is not supposed to be
    • routing has to be double checked
  • asymmetric routing if there is already another default gateway (I suppose there is)
    • routing has to be double checked
  • L3 loop (risk seems very very low here)
    • routing has to be double checked

As conclusion, routing has to be double checked :grin:

 

Mig

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Userlevel 5
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Martin,

 

Doing so, you’ll add a L3 interface to your EWC.

Possible impacts are:

  • routing traffic that is not supposed to be
    • routing has to be double checked
  • asymmetric routing if there is already another default gateway (I suppose there is)
    • routing has to be double checked
  • L3 loop (risk seems very very low here)
    • routing has to be double checked

As conclusion, routing has to be double checked :grin:

 

Mig

Userlevel 6
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Hi Mig,

Thank you for getting back to me, really appreciate it.

Hoping you can help me understand, help me make better choices.

The VLAN this topology belongs to already has a default gateway that is routing traffic as you suspect.

Any device that gets an IP address on this VLAN will maintain that information, so effectively all will stay the same, the DG will be same router.

What I’m not understanding is why and how giving the EWC topology an IP address would cause those effects.

Routing will effectively still point to the same DG i.e. 192.168.0.1. /24 is the mask. The topology L3 interface will get an IP address of 192.168.0.250.

Many thanks

Martin

Userlevel 5
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Martin,

You won’t probably get any issue but there is to few info to be sure.

The EWC is acting as a router so if you add a L3 interface he will start to route this specific VLAN.

If you have other L3 interfaces, you can route them together in the EWC without going through the core.

All is conditional as I don’t know your setup/design (use OSPF on the EWC?, how many L3 interfaces?, detailed routing table, etc.)

Mig

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Hi Mig,

Thanks for getting back.

The EWC doesn’t currently use any other L3 interface, so going to take the plunge and enable this.

Will report back if all goes well.

Many thanks again.

It is wonder to get work with latest update which help to run

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