Virtual Routers
A virtual router is a function of the firewall
that participates in Layer 3 routing. The firewall uses virtual
routers to obtain routes to other subnets by you manually defining
static routes or through participation in one or more Layer 3 routing
protocols (dynamic routes). The routes that the firewall obtains
through these methods populate the IP routing information base (RIB)
on the firewall. When a packet is destined for a different subnet
than the one it arrived on, the virtual router obtains the best
route from the RIB, places it in the forwarding information base
(FIB), and forwards the packet to the next hop router defined in
the FIB. The firewall uses Ethernet switching to reach other devices
on the same IP subnet. (An exception to one best route going in
the FIB occurs if you are using ECMP, in which case all equal-cost
routes go in the FIB.)
The Ethernet, VLAN, and tunnel interfaces
defined on the firewall receive and forward Layer 3 packets. The
destination zone is derived from the outgoing interface based on
the forwarding criteria, and the firewall consults policy rules to
identify the security policies that it applies to each packet. In
addition to routing to other network devices, virtual routers can
route to other virtual routers within the same firewall if a next
hop is specified to point to another virtual router.
You can
configure Layer 3 interfaces on a virtual router to participate
with dynamic routing protocols (BGP, OSPF, OSPFv3, or RIP) as well
as add static routes. You can also create multiple virtual routers,
each maintaining a separate set of routes that aren’t shared between
virtual routers, enabling you to configure different routing behaviors
for different interfaces.
Each Layer 3 Ethernet, loopback,
VLAN, and tunnel interface defined on the firewall must be associated
with a virtual router. While each interface can belong to only one
virtual router, you can configure multiple routing protocols and
static routes for a virtual router. Regardless of the static routes
and dynamic routing protocols you configure for a virtual router,
one general configuration is required:
- Gather the required information from your network administrator.
- Interfaces on the firewall that you want to perform routing.
- Administrative distances for static, OSPF internal, OSPF external, IBGP, EBGP and RIP.
- Create a virtual router and apply interfaces to it.The firewall comes with a virtual router nameddefault. You can edit thedefaultvirtual router or add a new virtual router.
- Select.NetworkVirtual Routers
- Select a virtual router (the one nameddefaultor a different virtual router) orAddtheNameof a new virtual router.
- Select.Router SettingsGeneral
- ClickAddin theInterfacesbox and select an already defined interface from the drop-down.Repeat this step for all interfaces you want to add to the virtual router.
- ClickOK.
- Set Administrative Distances for static and dynamic routing.Set Administrative Distances for types of routes as required for your network. When the virtual router has two or more different routes to the same destination, it uses administrative distance to choose the best path from different routing protocols and static routes, by preferring a lower distance.
- Static—Range is 10-240; default is 10.
- OSPF Internal—Range is 10-240; default is 30.
- OSPF External—Range is 10-240; default is 110.
- IBGP—Range is 10-240; default is 200.
- EBGP—Range is 10-240; default is 20.
- RIP—Range is 10-240; default is 120.
See ECMP if you want to leverage having multiple equal-cost paths for forwarding. - Commit virtual router general settings.ClickOKandCommit.
- Configure Ethernet, VLAN, loopback, and tunnel interfaces as needed.
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