User's Manual

Table Of Contents
476
Users Manual of CS-6306R
Chapter 47. IP-PBR Configuration
IP-PBR Configuration 47.1
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 hops 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-mapWORD
match ip addressWORD
set ip next-hopX.X.X.X [load-balance]
ip policy route-map WORD
IP-PBR is a little different from routers policy routing. IP-PBR chooses an effective next hop as the egress
and drops packets if no valid next hop available, while routers 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.
47.1.1 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.