User's Manual
Table Of Contents
- Chapter 1 INTRODUCTION
- Chapter 2 INSTALLATION
- Chapter 3 Switch Management
- Chapter 4 Basic Switch Configuration
- Chapter 5 File System Operations
- Chapter 6 Cluster Configuration
- Chapter 7 Port Configuration
- Chapter 8 Port Isolation Function Configuration
- Chapter 9 Port Loopback Detection Function Configuration
- Chapter 10 ULDP Function Configuration
- Chapter 11 LLDP Function Operation Configuration
- Chapter 12 Port Channel Configuration
- Chapter 13 Jumbo Configuration
- Chapter 14 EFM OAM Configuration
- Chapter 15 VLAN Configuration
- Chapter 16 MAC Table Configuration
- Chapter 17 MSTP Configuration
- Chapter 18 QoS Configuration
- Chapter 19 Flow-based Redirection
- Chapter 20 Egress QoS Configuration
- Chapter 21 Flexible Q-in-Q Configuration
- Chapter 22 Layer 3 Forward Configuration
- Chapter 23 ARP Scanning Prevention Function Configuration
- Chapter 24 Prevent ARP, ND Spoofing Configuration
- Chapter 25 ARP GUARD Configuration
- Chapter 26 ARP Local Proxy Configuration
- Chapter 27 Gratuitous ARP Configuration
- Chapter 28 Keepalive Gateway Configuration
- Chapter 29 DHCP Configuration
- Chapter 30 DHCPv6 Configuration
- Chapter 31 DHCP option 82 Configuration
- Chapter 32 DHCPv6 option37, 38
- Chapter 33 DHCP Snooping Configuration
- Chapter 34 Routing Protocol Overview
- Chapter 35 Static Route
- Chapter 36 RIP
- Chapter 37 RIPng
- Chapter 38 OSPF
- Chapter 39 OSPFv3
- Chapter 40 BGP
- 40.1 Introduction to BGP
- 40.2 BGP Configuration Task List
- 40.3 Configuration Examples of BGP
- 40.3.1 Examples 1: configure BGP neighbor
- 40.3.2 Examples 2: configure BGP aggregation
- 40.3.3 Examples 3: configure BGP community attributes
- 40.3.4 Examples 4: configure BGP confederation
- 40.3.5 Examples 5: configure BGP route reflector
- 40.3.6 Examples 6: configure MED of BGP
- 40.3.7 Examples 7: example of BGP VPN
- 40.4 BGP Troubleshooting
- Chapter 41 MBGP4+
- Chapter 42 Black Hole Routing Manual
- Chapter 43 GRE Tunnel Configuration
- Chapter 44 ECMP Configuration
- Chapter 45 BFD
- Chapter 46 BGP GR
- Chapter 47 OSPF GR
- Chapter 48 IPv4 Multicast Protocol
- 48.1 IPv4 Multicast Protocol Overview
- 48.2 PIM-DM
- 48.3 PIM-SM
- 48.4 MSDP Configuration
- 48.4.1 Introduction to MSDP
- 48.4.2 Brief Introduction to MSDP Configuration Tasks
- 48.4.3 Configuration of MSDP Basic Function
- 48.4.4 Configuration of MSDP Entities
- 48.4.5 Configuration of Delivery of MSDP Packet
- 48.4.6 Configuration of Parameters of SA-cache
- 48.4.7 MSDP Configuration Examples
- 48.4.8 MSDP Troubleshooting
- 48.5 ANYCAST RP Configuration
- 48.6 PIM-SSM
- 48.7 DVMRP
- 48.8 DCSCM
- 48.9 IGMP
- 48.10 IGMP Snooping
- 48.11 IGMP Proxy Configuration
- Chapter 49 IPv6 Multicast Protocol
- Chapter 50 Multicast VLAN
- Chapter 51 ACL Configuration
- Chapter 52 802.1x Configuration
- 52.1 Introduction to 802.1x
- 52.2 802.1x Configuration Task List
- 52.3 802.1x Application Example
- 52.4 802.1x Troubleshooting
- Chapter 53 The Number Limitation Function of Port, MAC in VLAN and IP Configuration
- 53.1 Introduction to the Number Limitation Function of Port, MAC in VLAN and IP
- 53.2 The Number Limitation Function of Port, MAC in VLAN and IP Configuration Task Sequence
- 53.3 The Number Limitation Function of Port, MAC in VLAN and IP Typical Examples
- 53.4 The Number Limitation Function of Port, MAC in VLAN and IP Troubleshooting Help
- Chapter 54 Operational Configuration of AM Function
- Chapter 55 TACACS+ Configuration
- Chapter 56 RADIUS Configuration
- Chapter 57 SSL Configuration
- Chapter 58 IPv6 Security RA Configuration
- Chapter 59 VLAN-ACL Configuration
- Chapter 60 MAB Configuration
- Chapter 61 PPPoE Intermediate Agent Configuration
- Chapter 62 SAVI Configuration
- Chapter 63 Web Portal Configuration
- Chapter 64 VRRP Configuration
- Chapter 65 IPv6 VRRPv3 Configuration
- Chapter 66 MRPP Configuration
- Chapter 67 ULPP Configuration
- Chapter 68 ULSM Configuration
- Chapter 69 Mirror Configuration
- Chapter 70 RSPAN Configuration
- Chapter 71 sFlow Configuration
- Chapter 72 SNTP Configuration
- Chapter 73 NTP Function Configuration
- Chapter 74 DNSv4/v6 Configuration
- Chapter 75 Summer Time Configuration
- Chapter 76 Monitor and Debug
- Chapter 77 Reload Switch after Specified Time
- Chapter 78 Debugging and Diagnosis for Packets Received and Sent by CPU
- Chapter 79 VSF
- Chapter 80 PoE Configuration
- Chapter 81 SWITCH OPERATION
- Chapter 82 TROUBLESHOOTING
- Chapter 83 APPENDIX A
- Chapter 84 GLOSSARY
31-6
31.3 DHCP option 82 Application Examples
Figure 31-1 A DHCP option 82 typical application example
In the above example, layer 2 switches Switch1 and Switch2 are both connected to layer 3 switch Switch3,
Switch 3 will transmit the request message from DHCP client to DHCP serer as DHCP Relay Agent. It will also
transmit the reply message from the server to DHCP client to finish the DHCP protocol procedure. If the
DHCP option 82 is disabled, DHCP server cannot distinguish that whether the DHCP client is from the
network connected to Switch1 or Switch2. So, all the PC terminals connected to Switch1 and Switch2 will get
addresses from the public address pool of the DHCP server. After the DHCP option 82 function is enabled,
since the Switch3 appends the port information of accessing Switch3 to the request message from the client,
the server can tell that whether the client is from the network of Swich1 or Swich2, and thus can allocate
separate address spaces for the two networks, to simplify the management of networks.
The following is the configuration of Switch3(MAC address is 00:03:4f:02:33:01):
Switch3(Config)#service dhcp
Switch3(Config)#ip dhcp relay information option
Switch3(Config)#ip forward-protocol udp bootps
Switch3(Config)#interface vlan 3
Switch3(Config-if-vlan3)#ip address 192.168.10.222 255.255.255.0
Switch3(Config-if-vlan2)#ip address 192.168.102.2 255.255.255.0
Switch3(Config-if-vlan2)#ip helper 192.168.10.88
Switch1
Switch2
DHCP Client PC1
DHCP Client PC2
DHCP Server
Vlan2:ethernet1/2
Vlan2:ethernet1/3
DHCP Relay Agent
Switch3
Vlan3