User's Manual

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Chapter 66 IP-PBR Configuration
66.1 IP-PBR Configuration
IP-PBR realizes software PBR functions through the hardware of switch chip.
PBR stands for Policy Based Routing. PBR enables users to rely on a certain policy not on routing protocol for
routing. Software based PBR supports multiple policies and rules and also load balance. You can designate
the next hop’s IP address or port for those packets that are in line with policy. PBR supports load balance and
applies multiple next-hop IP addresses or ports on those policy-supported packets.
Only when the next-hop egress ARP designated by route map is already learned can IP-PBR regard that this
egress is valid and then the corresponding rule is effective. When a packet satisfies IP-PBR policy, the
hardware directly forwards this packet to the next-hop egress that the rule specifies. This process is finished
by the hardware without the operation of CPU. The packets forwarded by IP-PBR have the highest priority and
only those packets unmatched with IP-PBR rule are forwarded to CPU.
The current IP-PBR supports the IP ACL policy and the next-hop IP address policy. When multiple next hops
are configured, the first effect next hop is chosen. IP-PBR also supports equivalent routing that is realized by
the switch chip. Hardware equivalent routing needs no extra configuration.
IP-PBR supports the following policy routing commands:
route-map WORD
match ip address WORD
set ip next-hop X.X.X.X [load-balance]
ip policy route-map WORD
IP-PBR is a little different from router’s policy routing. IP-PBR chooses an effective next hop as the
egress and drops packets if no valid next hop available, while router’s policy routing selects an
effective next hop but packet loss happens if this next hop has not learned ARP. Once multiple
sequences are set, one difference between IP-PBR and software policy routing must be noted.
Software policy routing always chooses high-priority sequence routes no matter whether IP
address matched by high-priority sequences overlaps with that matched by low-priority sequences
and whether these routes are effective, while IP-PBR chooses low-priority sequence routes when
high-priority sequence routes invalidate.
66.1.1 Enabling or Disabling IP-PBR Globally
Run the following commands in global configuration mode.
Command Purpose
ip pbr
The IP-PBR function is disabled by default.
no ip pbr
Resumes the default settings.
IP-PBR is disabled by default.
66.1.2 ISIS Configuration Task List
To configure IP-PBR, do as follows:
1) Create ACL;