Ip Routing Policy; Introduction To Ip Routing Policy - 3Com 8807 Configuration Manual

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Introduction to IP
Routing Policy
Filter
IP R
OUTING
When a router advertises or receives routing information, it possibly needs to
implement some policies to filter the routing information, so as to receive or
advertise the routing information which can meet the specified condition only. A
routing protocol, e.g. RIP, may need import the routing information discovered by
other protocols to enrich its routing knowledge. While importing the routing
information, it possibly only needs import the information meeting the conditions
and set some special attributes to make them meet its requirement.
For implementing the routing policy, you need define a set of matching rules by
specifying the characteristics of the routing information to be filtered. You can set
the rules based on such attributes like destination address and source address of
the information. The matching rules can be set in advance and then used in the
routing policy to advertise, receive and import the route information.
In Switch 8800 Family series, five kinds of filters, Route-policy, ACL, AS-path,
Community-list, and IP-prefix, are provided to be called by the routing protocols.
The following sections introduce these filters respectively.
ACL
The access control list (ACL) used by routing policy can be divided into the
following types:
Number-based basic ACLs
■
Name-based basic ACLs
■
Number-based advanced ACLs
■
Name-based advanced ACLs
■
Number-based L2 ACLs
■
Name-based L2 ACLs
■
For routing information filtering, the basic ACL is generally used. When users
define the ACL, they will define the range of an IP address or subnet to the
destination network segment address or the next-hop address of the routing
information. If an advanced ACL is used, perform the matching operation by the
specified source address range.
IP-prefix
The function of the IP-prefix is similar to that of ACL, but it is more flexible and
easy for the users to understand. When the IP-prefix is applied to the routing
information filtering, its matching objects are the destination address information
domain of the routing information.
P C
OLICY ONFIGURATION