Network Internal Loop

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Fnlz
Fnlz Posts: 5 image  Freshman Member
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edited April 2021 in Security

Hello Guys,

I hope someone can help me with my Problem.

firefox_bRWCf3CRji.png

A customer of us got a new connection with SIP-Trunking. Everything is working fine till we connect the Lancom to the Switch, like shown above. It is needed for the telephone system to communicate.

As soon as we connect it, the Internet goes down and enters some kind of loop.

Is it possible that the WAN Port in our Zyxel is missconfigured?

If yes, is there a sample-conf to setup the WAN Port for Ethernet?


Greetings.

Accepted Solution

  • mMontana
    mMontana Posts: 1,487 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments
    edited September 2019 Answer ✓
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    Can you change the Lancom 883+ subnet (and accordingly, USG115 Wan Port subnet)?

    Try to use something different just like 192.168.250.0/24 subnet.

    Long story short: use the same subnet on two different interfaces (not ports) AFAIK is not possible.

All Replies

  • mMontana
    mMontana Posts: 1,487 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments
    edited September 2019 Answer ✓
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    Can you change the Lancom 883+ subnet (and accordingly, USG115 Wan Port subnet)?

    Try to use something different just like 192.168.250.0/24 subnet.

    Long story short: use the same subnet on two different interfaces (not ports) AFAIK is not possible.

  • Fnlz
    Fnlz Posts: 5 image  Freshman Member
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    https://businessforum.zyxel.com/discussion/comment/9797#Comment_9797

    I will try it out, thanks :)

  • mMontana
    mMontana Posts: 1,487 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments
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    any news to share, @Fnlz ?

  • Zyxel_Cooldia
    Zyxel_Cooldia Posts: 1,590 image  Zyxel Employee
    Zyxel Certified Network Administrator - Security Zyxel Certified Sales Associate 100 Answers 1000 Comments
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    Hi @Fnlz,

    What is the Lan IP subnet of USG in this topology?


  • Fnlz
    Fnlz Posts: 5 image  Freshman Member
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    edited September 2019
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    Sorry for the late answer.

    @mMontana 's solution did the job.
    Thank you so much guys.
  • mMontana
    mMontana Posts: 1,487 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments
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    Consider to split the switch into 2 vlans, for avoiding dual DHCP servers.
  • Fnlz
    Fnlz Posts: 5 image  Freshman Member
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    We already did 2 vlans, but for the guest wifi.
    The DHCP server is disabled on the lancom, since normal clients obtain the IP through the Zyxel USG DHCP.
  • mMontana
    mMontana Posts: 1,487 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments
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    Thanks for the explanation. Have a lot of fun.

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