688
PowerConnect B-Series FCX Configuration Guide
53-1002266-01
General operating principles
24
•
Receive LLDP information only
Transmit mode
An LLDP agent sends LLDP packets to adjacent LLDP-enabled devices. The LLDP packets contain
information about the transmitting device and port.
An LLDP agent initiates the transmission of LLDP packets whenever the transmit countdown timing
counter expires, or whenever LLDP information has changed. When a transmit cycle is initiated,
the LLDP manager extracts the MIB objects and formats this information into TLVs. The TLVs are
inserted into an LLDPDU, addressing parameters are prepended to the LLDPDU, and the
information is sent out LLDP-enabled ports to adjacent LLDP-enabled devices.
Receive mode
An LLDP agent receives LLDP packets from adjacent LLDP-enabled devices. The LLDP packets
contain information about the transmitting device and port.
When an LLDP agent receives LLDP packets, it checks to ensure that the LLDPDUs contain the
correct sequence of mandatory TLVs, then validates optional TLVs. If the LLDP agent detects any
errors in the LLDPDUs and TLVs, it drops them in software. TLVs that are not recognized but do not
contain basic formatting errors, are assumed to be valid and are assigned a temporary
identification index and stored for future possible alter retrieval by network management. All
validated TLVs are stored in the neighbor database.
LLDP packets
LLDP agents transmit information about a sending device/port in packets called LLDP Data Units
(LLDPDUs). All the LLDP information to be communicated by a device is contained within a single
1500 byte packet. A device receiving LLDP packets is not permitted to combine information from
multiple packets.
As shown in
Figure 117
, each LLDPDU has three mandatory TLVs, an End of LLDPDU TLV, plus
optional TLVs as selected by network management.
FIGURE 117
LLDPDU packet format
Each LLDPDU consists of an untagged Ethernet header and a sequence of short, variable length
information elements known as TLVs.
TLVs have Type, Length, and Value fields, where:
•
Type identifies the kind of information being sent
•
Length indicates the length (in octets) of the information string
•
Value is the actual information being sent (for example, a binary bit map or an alpha-numeric
string containing one or more fields).
Ch
ass
i
s
ID
TLV
Port ID
TLV
Time to
Live TLV
Option
a
l
TLV
Option
a
l
TLV
End of
LLDPDU TLV
...
M
M
M
M
M = m
a
nd
a
tory TLV (req
u
ired for
a
ll LLDPDU
s
)
Содержание PowerConnect B-FCXs
Страница 1: ...53 1002266 01 18 March 2011 PowerConnect B Series FCX Configuration Guide ...
Страница 136: ...94 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Viewing information about software licenses 4 ...
Страница 228: ...186 PowerConnect B Series FCX Configuration Guide 53 1002266 01 PowerConnect B Series FCX hitless stacking 5 ...
Страница 229: ...PowerConnect B Series FCX Configuration Guide 187 53 1002266 01 PowerConnect B Series FCX hitless stacking 5 ...
Страница 230: ...188 PowerConnect B Series FCX Configuration Guide 53 1002266 01 PowerConnect B Series FCX hitless stacking 5 ...
Страница 248: ...206 PowerConnect B Series FCX Configuration Guide 53 1002266 01 IPv6 management commands 7 ...
Страница 346: ...304 PowerConnect B Series FCX Configuration Guide 53 1002266 01 802 1s Multiple Spanning Tree Protocol 8 ...
Страница 374: ...332 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Jumbo frame support 9 ...
Страница 424: ...382 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Virtual Switch Redundancy Protocol VSRP 10 ...
Страница 568: ...526 PowerConnect B Series FCX Configuration Guide 53 1002266 01 CLI examples 14 ...
Страница 588: ...546 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Sample application 15 ...
Страница 674: ...632 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Enabling or disabling layer 2 switching 19 ...
Страница 684: ...642 PowerConnect B Series FCX Configuration Guide 53 1002266 01 VLAN based mirroring 20 ...
Страница 724: ...682 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Reading CDP packets 23 ...
Страница 768: ...726 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Clearing cached LLDP neighbor information 24 ...
Страница 930: ...888 PowerConnect B Series FCX Configuration Guide 53 1002266 01 26 ...
Страница 948: ...906 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Configuring MLD snooping 27 ...
Страница 962: ...920 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Displaying CPU utilization statistics 28 ...
Страница 1022: ...980 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Displaying OSPF information 29 ...
Страница 1142: ...1100 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Clearing diagnostic buffers 30 ...
Страница 1258: ...1216 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Using Secure copy with SSH2 33 ...
Страница 1314: ...1272 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Displaying port security information 35 ...
Страница 1348: ...1306 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Example configurations 36 ...
Страница 1406: ...1364 PowerConnect B Series FCX Configuration Guide 53 1002266 01 IP source guard 39 ...
Страница 1422: ...1380 PowerConnect B Series FCX Configuration Guide 53 1002266 01 SNMP v3 Configuration examples 40 ...