Dell PowerEdge FN I/O Module Configuration Guide 9.10(0.0)

Policy-based Routing (PBR) enables you to make routing decisions based on policies applied to a specific interface. When a router receives a packet it normally decides where to forward it based on the destination address in the packet, which is used to look up an entry in a routing table. However, in some cases, there may be a need to forward the packet based on other criteria: size, source, protocol type, destination, etc. For example, a network administrator might want to forward a packet that uses TCP across a different next-hop than packets using ICMP.

Rules for PBR can also be a combination of things:

When the packet comes from this source and wants to go to that destination then route it to next-hop or onto that specific interface. This permits routing over different links or towards different networks even while the destination is the same but depending on where the packet originates.

To enable a PBR, you create a Redirect List. Redirect lists are defined by rules, or routing policies. The following parameters can be defined in the routing policies or rules:

• IP address of the forwarding router (next-hop IP address)
• Protocol as defined in the header
• Source IP address and mask
• Destination IP address and mask
• Source port
• Destination port
• TCP Flags

Once a redirect-list is applied to an interface, all traffic passing through it is subjected to the rules defined in the redirect-list.

The traffic is forwarded based on the following:

• Next-hop addresses are verified. If the specified next hop is reachable, then the traffic is forwarded to the specified next-hop.
• If the specified next-hops are not reachable, then the normal routing table is used to forward the traffic.
• Dell Networking OS supports multiple next-hop entries in the redirect lists.
• Redirect-Lists are applied at Ingress.

PBR with Redirect-to-Tunnel Option:

The user can provide a tunnel id for a redirect rule. In this case, the resolved next hop would be the tunnel interface IP. The qualifiers of the rule would be pertaining to the inner IP details. For next hop to be a tunnel interface user needs to provide tunnel id mandatory. Instead if user provides the tunnel destination IP as next hop, that would be treated as IPv4 next hop and not tunnel next hop.

PBR with Multiple Tacking Option:

Policy based routing with multiple tracking option extends and introduces the capabilities of object tracking to verify the next hop IP address before forwarding the traffic to the next hop. The verification method is made transparent to the user. The multiple tracking options feature is most suitable for routers which have multiple devices as the next hop (primarily indirect next-hops and/or Tunnel Interfaces in this case). It allows you to backup Indirect Next-hop with another, choose the specific Indirect Next-hop and/or Tunnel Interface which is available by sending ICMP pings to verify reach ability and/or check the Tunnel Interface UP or DOWN status, and then route traffic out to the next-hop and/or Tunnel Interface.