Brocade 6910 Ethernet Access Switch Diagnostic Guide (Supporting R2.2.0.0) - Manual (Page 33)

Brocade 6910 Ethernet Access Switch Diagnostic Guide 23
53-1002653-01
DRAFT: BROCADE CONFIDENTIAL
Chapter
4
Layer 2 Protocol Diagnostics
In this chapter
This chapter describes Layer 2 troubleshooting and diagnostic processes for the Brocade 6910
switch.
• MAC address learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
• Spanning Tree Protocol and derivatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
• LACP trunking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
• VLAN trunking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
• Ethernet Ring Protection switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
• Connectivity Fault Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
• Operation, Administration and Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . 39
MAC address learning
In MAC address learning, the source MAC address of each received packet is stored so that future
packets destined for that address can be forwarded only to the interface where that address is
located. (Packets destined for unrecognized addresses are forwarded out every bridge interface.)
MAC address learning, defined in the IEEE 802.1 standard, helps minimize traffic on the attached
LANs.
Address Resolution Protocol
Switches use Address Resolution Protocol (ARP) to learn the MAC addresses of devices on the
network. The switch sends an ARP request that contains the IP address of a device, and receives
the MAC address for that device in an ARP reply. These dynamically learned entries are stored in
the ARP cache. You can also manually configure MAC addresses, which are called static entries.
Dynamic and static ARP entries in the ARP cache resemble the following:
Console# show arp
ARP Cache Timeout: 1200 (seconds)
IP Address MAC Address Type Interface
--------------- ----------------- --------- -----------
192.168.0.2 74-8E-F8-68-02-30 other VLAN1
192.168.0.9 11-22-33-44-55-66 static VLAN1
192.168.0.99 00-E0-29-94-34-64 dynamic VLAN1
Total entry : 3