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Forum Discussion

Piotr_Lewandows's avatar
Piotr_Lewandows
Icon for Altostratus rankAltostratus
May 09, 2016

Static routes and VLAN/Tunnel as Resource Type

Hi,   I was trying to figure out how VLAN/Tunnel type of static route is working. Looking at the GUI help as well as Routing docs I am still puzzled.   I would appreciate some real life example...
BIG-IP
devops
LTM
static route
vlan route
zeiss_63263's avatar
zeiss_63263
Historic F5 Account
May 09, 2016

Hi Piotr,

 

If you're asking what the BIG-IP does when you set a static route to point to a VLAN or tunnel instead of (for example) a next-hop gateway, then the BIG-IP should ARP for the destination address regardless of the configured IP addresses on the interface itself. The BIG-IP will ARP for the destination address using a locally configured source self-ip on that VLAN/tunnel.

 

That means that you need a proxy ARP device upstream to see the ARP request and respond.

 

In earlier software versions and under certain conditions, the BIG-IP would broadcast packets (L2 ff:ff:ff:ff:ff:ff) to the IP destination when the ARP goes unanswered. Some routers would happily route that, but the behaviour was deemed to be undesirable and should no longer occur.

 

Regards, Michael.