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3750 Inter Vlans ignore gateway of last resort

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  • 3750 Inter Vlans ignore gateway of last resort

    Hi

    I have a stack containing two Cisco 3750 Switches. Ip routing is enabled and we have created 5 VLans. 1 (Default) to 5

    Routing between VLans is OK. Routing from VLans to anything in the routing table is OK.

    Problem is when the address is not in the routing table. VLAN1 is OK as it uses the gateway of last resort. However the other VLans (2 - 5) fail to find the route. It is almost like they are ignoring the default gateway setting.

    I have followed the Cisco document 41860. "How to configure intervlan routing on layer 3 switches" for the configuration.

    Can anyone advise what configuration might be missing?

  • #2
    Re: 3750 Inter Vlans ignore gateway of last resort

    If you could upload the config, that might help. It will give the chance for people to diagnose the issue, but don't forget to omit the sensitive bits.

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    • #3
      Re: 3750 Inter Vlans ignore gateway of last resort

      Managed to resolve the issue. In our case the defualt gateway was a chekpoint firewall.

      It has a module called smart defence. One of the features enabled was the antispoofing rule that blocks traffic from non specified subnets. As the VLANS were for new subnets the addresses were not configured and the firewall was dropping them.

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