Route to untagged traffic

[pietersaenen]

Hello All,

I have a situation where I could use some help.

My infrastructure is configured as followed:

A cisco router where dot1.q is used to create vlans. A stack of 2960S switches where all the vlans have been configured.

I need to connect some devices on one of those vlan's to a range that is unknown in my network. This is a range that was supplied by the building to connect to the intercom and videophones to operate doors etc... This is in the 192.168.1.0/24 range.

I managed to communicate with this 192.168.1.0/24 network if I create an SVI on my switches in this range, but how can I route from my vlans to this network?

Any help is appreciated.

Kind Regards

Pieter

[Giuseppe Larosa]

Hello @pietersaenen ,

assuming that the building subnet 192.168.1.0/24 is connected to a Vlan in the range you can do the following:

If you know which Vlan is for example Vlan 252 you can use a secondary address on the router used for inter VLAN routing

int gi0/0.252

enc dot1q 252

! ip address primary is left unchanged

ip address ....

ip address 192.168.1.254 255.255.255.0 secondary

This should solve your issue.

Hope to help

Giuseppe

[pietersaenen]

Hello Giuseppe,

I will try this and let know the outcome...

Thanks in advance

Pieter

[pietersaenen]

Hello Giuseppe,

I have tried to add a secondary ip address to the vlan that should be able to communicate with the building network, but still not able to ping the building network from 10.49.149.1

interface GigabitEthernet0/1.149
description Crestron
encapsulation dot1Q 149
ip address 192.168.1.151 255.255.255.0 secondary
ip address 10.49.149.1 255.255.255.0
ip helper-address 10.32.1.2
no ip proxy-arp

How should i configure the switchports where the building network is connected to?

Any ideas

Thanks in advance

Pieter

[Giuseppe Larosa]

Hello @pietersaenen ,

you need to take over the role of the default gateway for the building subnet 192.168.1.151 should be the default gateway for all the building connected devices.

If a default gateway is already deployed you would need to have its configuration changed so that it can have  a default route to next-hop 192.168.1.151.

This is what is missing now devices in the building subnet either have no default gateway configured or they have a default gateway configured that is not 192.168.1.151.

So you should check the configuration of two devices connected to the building subnet to understand what is the better next step.

Hope to help

Giuseppe

[pietersaenen]

Hello Giuseppe,

So I need to ask the building management what IP they use as default gateway for their network and configure this as secondary IP address on my router?

Pieter

[Giuseppe Larosa]

Hello @pietersaenen ,

please note that if that default gateway already exists it should be configured to point to your secondary address as next-hop for all the 10.x.y.0 subnets you have in use.

Using the same IP address of an already existing device either host or router would cause an address conflict in the LAN so it is not recommended.

If they configured a default gateway but that default gateway is just a place holder it is not in use you can re-use that IP as secondary on your router.

So yes you need to talk with people managing the building.

Check also that what you want to do is allowed by the building security policies

Hope to help

Giuseppe

[pietersaenen]

Hello Giuseppe,

So building management need to add a route on their side pointing to the secondary IP address I configure on my route?

Pieter

[pietersaenen]

So building management need to add a route on their side pointing to the secondary IP address I configure on my router?

[Giuseppe Larosa]

Hello @pietersaenen ,

yes if they have a router or multilayer switch that acts as default gateway for the building subnet

>> So building management need to add a route on their side pointing to the secondary IP address I configure on my route?

Hope to help

Giuseppe

[pietersaenen]

Hello @Giuseppe Larosa ,

I will contact the building management and ask to add a route. Will come back to you with the outcome...

Thanks in advance