Policy Route Maps; Set Criteria For Policy-Based Routing - Cisco Nexus 7000 Series Configuration Manual

Information About Policy Based Routing
S e n d d o c u m e n t c o m m e n t s t o n e x u s 7 k - d o c f e e d b a c k @ c i s c o . c o m .
Policy-based routing includes the following features:
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This section includes the following topics:
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Policy Route Maps

Each entry in a route map contains a combination of match and set statements. The match statements
define the criteria for whether appropriate packets meet the particular policy (that is, the conditions to
be met). The set clauses explain how the packets should be routed once they have met the match criteria.
You can mark the route map statements as permit or deny. If the statement is marked as a deny, the
packets that meet the match criteria are sent back through the normal forwarding channels
(destination-based routing is performed). If the statement is marked as permit and the packets meet the
match criteria, all the set clauses are applied. If the statement is marked as permit and the packets do not
meet the match criteria, then those packets are also forwarded through the normal routing channel.
Note Policy routing is specified on the interface that receives the packets, not on the interface from which the
packets are sent.

Set Criteria for Policy-Based Routing

The set criteria in a route map is evaluated in the order listed in the route map. Set criteria specific to
route maps used for policy-based routing are as follows:
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Cisco Nexus 7000 Series NX-OS Unicast Routing Configuration Guide, Release 4.x
17-2
Source-based routing—Routes traffic originating from different sets of users through different
connections across the policy routers.
Quality of Service (QoS)—Differentiates traffic by setting the precedence or type of service (ToS)
values in the IP packet headers at the periphery of the network and leveraging queuing mechanisms
to prioritize traffic in the core or backbone of the network (see the Cisco Nexus 7000 Series NX-OS
Quality of Service Configuration Guide, Release 4.x).
Load sharing—Distributes traffic among multiple paths based on the traffic characteristics.
Policy Route Maps, page 17-2
Set Criteria for Policy-Based Routing, page 17-2
List of specified IP addresses—The IP address can specify the adjacent next-hop router in the path
toward the destination to which the packets should be forwarded. The first IP address associated
with a currently up connected interface is used to route the packets.
You can optionally configure the set criteria for next-hop addresses to load balance traffic across
up to 16 IP addresses. In this case, Cisco NX-OS sends all traffic for each IP flow to a particular
IP next-hop address.
List of default next-hop IP addresses—Route to the interface or the next-hop address specified by
this set statement only if there is no explicit route for the destination address of the packet in the
routing table.
You can optionally configure the set criteria for the default next-hop addresses to load balance
traffic across up to 16 IP addresses. In this case, Cisco NX-OS sends all traffic for each IP flow
to a particular IP next-hop address.
Chapter 17 Configuring Policy-Based Routing
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