08-28-2019 02:04 AM - edited 08-28-2019 02:15 AM
Hello,
at my workplace we have 2 routers put together with VRRP into a virtual router. Router X being master and Y back-up. All our vlans have basicly the same config.
A colleague of mine wanted to try somthing with a new vlan and added it on router Y. For this vlan he didn't config vrrp so that specific vlan is only running on router Y.
My question now is, when everything is set-up with vrrp should this vlan be set-up with vrrp on both physical routers aswell? We tried to get an IP adress on a client for that specific vlan but it didn't work. Is vrrp the cause?
Solved! Go to Solution.
08-28-2019 05:59 AM
Hello Benjamin,
it is fine to define the new Vlan and IP subnet only on router Y, but router X needs to be informed of its existence.
with shared Vlan I mean a DIFFERENT vlan to give Router X a valid IP next-hop for the specific static route.
Example:
new vlan is 781 and new IP subnet is 10.20.221.0/24
vlan 50 is shared between RX and RY 10.20.50.2 on RX and 10.20.50.3 on RY
then on RX you can do the following:
ip route 10.20.221.0 255.255.255.0 10.20.50.3
I hope now it is more clear with the example.
Hope to help
Giuseppe
08-28-2019 02:18 AM
Hello Benjamin,
>> My question now is, when everything is set-up with vrrp should this vlan be set-up with vrrp on both physical routers aswell?
Yes, VRRP requires both routers to be connected to the same Vlan / IP subnet to work
>> We tried to get an IP adress on a client for that specific vlan but it didn't work. Is vrrp the cause?
No, verify if you have configured an ip helper-address <DHCP-server> on the new SVI for the new Vlan.
Also the IP subnet of the new Vlan has to be advertised in IGP for example in EIGRP or OSPF.
also on the DHCP server a new DHCP pool of addresses for the new subnet needs to be configured.
Hope to help
Giuseppe
08-28-2019 03:53 AM
08-28-2019 05:11 AM
Hello Benjamin,
Router X needs a specific static route pointing to Router Y on a shared Vlan to know that the new subnet is alive.
If the /19 aggregate route points to RX and RX does not know about the new IP subnet packets are silently dropped = sent to Null0.
Hope to help
Giuseppe
08-28-2019 05:47 AM
08-28-2019 05:59 AM
Hello Benjamin,
it is fine to define the new Vlan and IP subnet only on router Y, but router X needs to be informed of its existence.
with shared Vlan I mean a DIFFERENT vlan to give Router X a valid IP next-hop for the specific static route.
Example:
new vlan is 781 and new IP subnet is 10.20.221.0/24
vlan 50 is shared between RX and RY 10.20.50.2 on RX and 10.20.50.3 on RY
then on RX you can do the following:
ip route 10.20.221.0 255.255.255.0 10.20.50.3
I hope now it is more clear with the example.
Hope to help
Giuseppe
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