Administrator Guide

CONFIGURATION mode
ipv6 control-plane [egress filter]
3 Create a Layer 3 ACL using permit rules with the count option to describe the desired CPU trac.
CONFIG-NACL mode
permit ip {source mask | any | host ip-address} {destination mask | any | host ip-address}
count [monitor [session-id]]
Dell Networking OS Behavior: Virtual router redundancy protocol (VRRP) hellos and internet group management protocol (IGMP) packets
are not aected when you enable egress ACL ltering for CPU trac. Packets sent by the CPU with the source address as the VRRP
virtual IP address have the interface MAC address instead of VRRP virtual MAC address.
IP Prex Lists
IP prex lists control routing policy. An IP prex list is a series of sequential lters that contain a matching criterion (examine IP route prex)
and an action (permit or deny) to process routes. The lters are processed in sequence so that if a route prex does not match the criterion
in the rst lter, the second lter (if congured) is applied. When the route prex matches a lter, Dell Networking OS drops or forwards
the packet based on the lter’s designated action. If the route prex does not match any of the lters in the prex list, the route is dropped
(that is, implicit deny).
A route prex is an IP address pattern that matches on bits within the IP address. The format of a route prex is A.B.C.D/X where A.B.C.D
is a dotted-decimal address and /X is the number of bits that should be matched of the dotted decimal address. For example, in
112.24.0.0/16, the rst 16 bits of the address 112.24.0.0 match all addresses between 112.24.0.0 to 112.24.255.255.
The following examples show permit or deny lters for specic routes using the le and ge parameters, where x.x.x.x/x represents a route
prex:
• To deny only /8 prexes, enter deny x.x.x.x/x ge 8 le 8.
• To permit routes with the mask greater than /8 but less than /12, enter permit x.x.x.x/x ge 8.
• To deny routes with a mask less than /24, enter deny x.x.x.x/x le 24.
• To permit routes with a mask greater than /20, enter permit x.x.x.x/x ge 20.
The following rules apply to prex lists:
• A prex list without any permit or deny lters allows all routes.
• An “implicit deny” is assumed (that is, the route is dropped) for all route prexes that do not match a permit or deny lter in a
congured prex list.
• After a route matches a lter, the lter’s action is applied. No additional lters are applied to the route.
Implementation Information
In Dell Networking OS, prex lists are used in processing routes for routing protocols (for example, router information protocol [RIP], open
shortest path rst [OSPF], and border gateway protocol [BGP]).
NOTE
: It is important to know which protocol your system supports prior to implementing prex-lists.
Conguration Task List for Prex Lists
To congure a prex list, use commands in PREFIX LIST, ROUTER RIP, ROUTER OSPF, and ROUTER BGP modes.
Create the prex list in PREFIX LIST mode and assign that list to commands in ROUTER RIP, ROUTER OSPF and ROUTER BGP modes.
The following list includes the conguration tasks for prex lists, as described in the following sections.
Access Control Lists (ACLs)
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