Introduction To The Mac Address Table; Mac Address Table Features Supported By The S9300 - Huawei Quidway S9300 Configuration Manual

6 MAC Address Table Configuration

6.1 Introduction to the MAC Address Table

This section describes the concept of the MAC address table.
Each Line Processing Unit (LPU) on the S9300 has a MAC address table. The MAC address
table stores the MAC addresses of other devices learned by the S9300, the VLAN IDs, and the
outgoing interfaces that are used to send data. Before forwarding the data, the S9300 searches
the MAC address table based on the destination MAC address and the VLAN ID of the data to
find the corresponding outgoing interface rapidly. This reduces the number of broadcast packets.
The network administrator can manually configure the static entries in the MAC address table
to bind user devices to interfaces. This can improve the security of interfaces, preventing
unauthorized users from accessing the network.

6.2 MAC Address Table Features Supported by the S9300

This section describes the MAC address table features supported by the S9300.
Classification of MAC Address Entries
MAC address entries are classified into three categories, namely, dynamic entries, static entries,
and blackhole entries.
l
l
l
Capacity of a MAC Address Table
The maximum capacity of a MAC address table on the S9300 is 512 K, in which the total capacity
of static entries and blackhole entries is 4 K.
Limitation on MAC Address Learning
The capacity of a MAC address table is limited; therefore, if hackers forge a large number of
packets with different source MAC addresses and send the packets to the S9300, the MAC
address table of the S9300 may be full. After the MAC address table is crammed with MAC
address entries, the S9300 cannot learn the source MAC addresses in the normal packets received
by the interface any more.
The S9300 can limit the MAC address learning based on the interface, VLAN, or Virtual Switch
Instance (VSI). When the number of learned MAC address entries reaches the maximum, the
later received packets are discarded or forwarded according to the configuration. The S9300 can
generate alarms to alert the network administrator in this situation. In this manner, the number
of access users is flexibly controlled and hackers are prevented from using MAC addresses to
attack user devices or networks.
6-2
Dynamic entries are the MAC address entries generated after the S9300 automatically
learns the source MAC addresses of the received packets. The dynamic entries will be aged
after a certain period.
Static entries are the manually configured MAC address entries. The static entries will not
be aged.
Blackhole entries are the manually configured MAC entries. They are used to discard the
data frames that have certain destination MAC addresses or source MAC addresses. The
blackhole entries will not be aged.
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
Quidway S9300 Terabit Routing Switch
Configuration Guide - Ethernet
Issue 03 (2009-08-20)