Ip Routing Policy; Introduction To Routing Policy - Planet XGS3-42000R User Manual

network the layer3 switch resides. Network mask consists of several cons ecutive binary 1's, and
usually in the format of dotted decimal (an address consists of 1 to 4 255's.) When "A ND" the
destination address with network mask, we can get the network address for the destination host or
the net work the layer3 s witch resides. For example, the network address of a host or the segment
the layer3 switch resides with a destination address of 200.1.1.1 and mask 255.255.255. 0 is
200.1. 1.0.
 Output interface: specify the interface of layer3 switch to forward IP packets.
 IP address of the next layer3 XGS3-42000R(next hop): specify the next layer3 switch the IP packet
will pass.
 Rout e entry priority: There may be several different next hop routes leading to the same destination.
Those routes may be discovered by different dynamic routing protocols or static routes manually
configured. The entry with the highest priority (smallest value) becomes the current best route. The
user can configure several routes of different priority to the same destination; layer3 switch will
choose one route for IP packet forwarding according to the priority order.
To prevent too large route table, a default route can be set. Once route table look up fails, the default route will
be chosen for forwarding packets.
The table below describes the routing protocols supported by switch and the default route look up priority
value.

33.2 IP Routing Policy

33.2.1 Introduction to Routing Policy

Some policies have to be applied when the router publishing and receiving routing messages so to filter
routing messages, such as only receiving or publishing routing messages meets the specified conditions. A
routing protocol maybe need redistribut e other routing messages found by other protocols such as OSPF so
to increase its own routing knowledge; when the router redistributing routing messages from other routing
protocols there may be only part of the qualified routing messages is needed, and some properties may have
to be configured to suit this protocol.
To achieve routing policy, first we have to define the characteristics of the routing messages to be applied with
routing policies, namely define a group matching rules. We can configure by different properties in the routing
messages such as destination address, the router address publishing the routing messages. The matching
rules can be previously configured to be applied in the routing publishing, rec eiving and distributing policies.
Five filters are provided in switch: route-map, acl, as-path, community-list and ip-prefix for use. We will
Routing Prot ocols or route type
Direct route
OSPF
Static route
RIP
OSPF ASE
IBGP
EBGP
Unknown route
Default priority value
0
110
1
120
150
200
20
255
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