Administrator Guide

Implementing Policy-based Routing with Dell
Networking OS
● Non-contiguous bitmasks for PBR
● Hot-Lock PBR
Non-contiguous bitmasks for PBR
Non-contiguous bitmasks for PBR allows more granular and flexible control over routing policies. Network addresses that are in
the middle of a subnet can be included or excluded. Specific bitmasks can be entered using the dotted decimal format.
Non-contiguous bitmask example
Dell#show ip redirect-list
IP redirect-list rcl0:
Defined as:
seq 5 permit ip 200.200.200.200 200.200.200.200 199.199.199.199 199.199.199.199
seq 10 redirect 1.1.1.2 tcp 234.224.234.234 255.234.234.234 222.222.222.222/24
seq 40 ack, Next-hop reachable(via Te 8/1/1)
Applied interfaces:
Te 8/2/1
Hot-Lock PBR
Hot Lock PBR allow you to add or delete new rules into an existing policy (already written into CAM) without disruption to
traffic flow. Existing entries in CAM are adjusted to accommodate the new entries. Hot Lock PBR is enabled by default.
Configuration Task List for Policy-based Routing
This section explains how to configure PBR on the system.
PBR Exceptions (Permit)
To create an exception to a redirect list, use thepermit command. Exceptions are used when a forwarding decision should be
based on the routing table rather than a routing policy.
The Dell EMC Networking OS assigns the first available sequence number to a rule configured without a sequence number and
inserts the rule into the PBR CAM region next to the existing entries. Because the order of rules is important, ensure that you
configure any necessary sequence numbers.
Never apply the permit statement because the redirect list covers all source and destination IP addresses.
ip redirect-list rcl0
seq 5 redirect 2.2.2.2 ip any any
seq 10 permit ip host 3.3.3.3 any
To ensure the permit permit statement or PBR exception is effective, use a lower sequence number, as shown:
ip redirect-list rcl0
seq 10 permit ip host 3.3.3.3 any
seq 15 redirect 2.2.2.2 ip any any
Apply a Redirect-list to an Interface using a Redirect-group
IP redirect lists are supported on physical interfaces as well as virtual local area network (VLAN) and port-channel interfaces.
NOTE:
When you apply a redirect-list on a port-channel, when traffic is redirected to the next hop and the destination
port-channel is shut down, the traffic is dropped. However, the traffic redirected to the destination port-channel is
sometimes switched.
694 Policy-based Routing (PBR)