Pbr Processing Logic - NETGEAR M4200 Software Administration Manual

To classify L3 routed traffic, the switch supports the following packet entities:
• The size of the packet
• Protocol of the payload (Protocol ID field in IP header)
• Source MAC address
• Source IP address
• Destination IP address
• Priority (802.1P priority)
NETGEAR's policy-based routing feature overrides routing decisions taken by the switch and
makes the packet follow different actions specified in the following order to define forwarding
criteria:
• List of next hop 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 active ARP entry is used to route the packets.
• List of default next hop IP addresses. This list indicates the next-hop routers to which a
packet must be routed if no active route exists for the packet's destination address in the
routing table. With the policy-based routing feature, a default route in the routing table is
not considered an active route for an unknown destination address.
• IP precedence. A numeric value can be specified to set the precedence in the IP packets
being forwarded. IP precedence value implies 3 IP precedence bits in the IP packet
header. With 3 bits, network administrators have 8 possible values for the IP precedence.
This value will be set in IPV4 header of packets when configured.

PBR Processing Logic

The processing logic used by policy-based routing is as follows when a packet is received on
an interface configured with a route map, the forwarding logic processes each route-map
statement according to the sequence number.
The route map with a permit statement uses the following logic:
• The incoming packet is matched against the criteria in the match term specified in the
route map. This match command can refer to an IP/MAC access list. An ACL that is used
in the match term itself includes one or more permit or deny rules. Now, the incoming
packet is matched against the rules in the AC, and a permit or deny decision is reached.
• If the decision reached in the previous step is permit, then policy-based routing executes
the action specified in set terms of the route-map statement over an incoming packet.
• If the decision reached in the earlier step is deny, then policy-based routing does not
apply any action that is specified in set terms in the route-map statement. In this situation,
the counter for this match statement is not incremented and the processing logic moves
to next route-map statement in the sequence. If no next route-map statement exists, the
processing logic terminates and the packet goes through standard destination-based
routing logic.
Managed Switches
PBR
147