Dynamic routing. Application route. Route filtering. Route summarization. Protocol preference. Configure multicast groups. Configure virtual path route cost. Configure Virtual Router redundancy protocol.
Configure network objects. Routing support for LAN segmentation. Inter-routing domain service. ECMP load balancing. Secure peering. Domain join and delegate user creation. IPsec tunnel termination. How to configure IPsec tunnels for virtual and dynamic paths. How to add IKE certificates.
How to view IPsec tunnel configuration. IPsec monitoring and logging. Eligibility for IPsec non-virtual path routes. IPsec null encryption. FIPS compliance. Palo Alto integration by using IPsec tunnels. Stateful firewall and NAT support.
Global firewall settings. Advanced firewall settings. Network address translation NAT. Static NAT. Dynamic NAT. Configure virtual WAN service. Configure firewall segmentation. Certificate authentication. Administrative interface. NDP router advertisement and prefix delegation group. WAN optimization. Enabling optimization and configuring the default feature settings.
Configuring optimization default tuning settings. Configuring optimization default application classifiers. Configuring optimization default service classes. Configuring optimization for a branch site. Configure SSL profiles. Citrix WAN optimization client plug-in. Hardware and software requirements.
Deploying appliances for use with plug-ins. Customizing the plug-in MSI file. Deploying plug-ins on Windows systems. SMB 3. How to articles. Interface groups. Configure virtual IP Address identity. Configure access interface. Configure virtual IP addresses. Configure GRE tunnels. Set up dynamic paths for branch to branch communication.
Monitoring and troubleshooting. Monitoring virtual WAN. Viewing statistical information. Viewing flow information. Viewing reports. Viewing firewall statistics. Emerging industry standard upon which tag switching is based. A VRF consists of an IP routing table, a derived forwarding table, a set of interfaces that use the forwarding table, and a set of rules and routing protocols that determine what goes into the forwarding table.
Skip to content Skip to search Skip to footer. Book Contents Book Contents. Find Matches in This Book. PDF - Complete Book 3. You can verify whether they have been disabled by checking your configuration file. If they have been disabled, the no service dhcp command will appear in the configuration file. Use the service dhcp command to reenable the functionality if necessary. Enter your password if prompted. Step 2 configure terminal Example: Router configure terminal Enters global configuration mode.
Step 4 ip helper-address address Example: Router config-if ip helper-address The address argument can be a specific DHCP server address, or it can be the network address if other DHCP servers are on the destination network segment.
Using the network address enables other servers to respond to DHCP requests. If you have multiple servers, you can configure one helper address for each server. The relay agent information option contains related suboptions. The DHCP server receives the packet, uses the suboptions to assign IP addresses and other configuration parameters to the packet, and forwards the packet back to the client.
The suboption fields are stripped off of the packet by the relay agent while forwarding the packet to the client. Figure 1. Note If the ip dhcp relay information command is configured in global configuration mode but not configured in interface configuration mode, the global configuration is applied to all interfaces. If the ip dhcp relay information command is configured in both global configuration mode and interface configuration mode, the interface configuration command takes precedence over the global configuration command.
However, the global configuration is applied to interfaces without the interface configuration. If the ip dhcp relay information command is not configured in global configuration mode but is configured in interface configuration mode, only the interface with the configuration option applied is affected.
All other interfaces are not impacted by the configuration. Step 2 configure terminal Example: Device configure terminal Enters global configuration mode. This function is disabled by default.
If an invalid message is received, the relay agent drops the packet. If a valid message is received, the relay agent removes the option field and forwards the packet.
Use the ip dhcp relay information check command to reenable this functionality if it has been disabled. Step 6 ip dhcp relay information trust-all Example: Device config ip dhcp relay information trust-all Optional Configures all interfaces on a router as trusted sources of the DHCP relay information option. By default, if the gateway address is set to all zeros in the DHCP packet and the relay agent information option is already present in the packet, the DHCP relay agent will discard the packet.
Use the ip dhcp relay information trust-all command to override this behavior and accept the packets. This command is useful if there is a switch placed between the client and the relay agent that may insert option Use this command to ensure that these packets do not get dropped. You can configure an individual interface as a trusted source of the DHCP relay information option by using the ip dhcp relay information trusted interface configuration mode command.
Step 8 show ip dhcp relay information trusted-sources Example: Device show ip dhcp relay information trusted-sources Optional Displays all interfaces that are configured to be a trusted source for the DHCP relay information option. If the ip dhcp relay information command is not configured in global configuration mode but is configured in interface configuration mode, only the interface on which the configuration option is applied is affected. However, if support for the relay agent information option is configured in global configuration mode, but not configured in interface configuration mode, the interface inherits the global configuration.
The ip dhcp relay information option-insert none interface configuration command is saved in the running configuration. This command takes precedence over any global relay agent information configuration. Use the ip dhcp relay information check-reply command to reenable this functionality if it has been disabled. The ip dhcp relay information check-reply none interface configuration command option is saved in the running configuration. Step 7 exit Example: Device config-if exit Exits interface configuration mode.
Step 8 Repeat Steps 3 through 7 to configure relay agent information settings on different interfaces. Before You Begin You should configure the unique identifier for each subscriber.
The server should be able to recognize the new suboption. Step 5 ip dhcp relay information option subscriber-id string Example: Router config-if ip dhcp relay information option subscriber-id newsubscriber Specifies that a DHCP relay agent add a subscriber identifier suboption to the relay information option.
The string argument can be up to a maximum of 50 characters and can be alphanumeric. Note If more than 50 characters are configured, the string is truncated. Note The ip dhcp relay information option subscriber-id command is disabled by default to ensure backward capability. Step 8 relay source ip-address subnet-mask Example: Device dhcp-config relay source This command is similar to the network command in a normal DHCP network pool, because it restricts the use of the address pool to packets arriving on the interface whose configured IP address and mask match the relay source configuration.
Step 10 relay target [ vrf vrf-name global ] ip-address Example: Device config-dhcp-pool-class relay target Step 5 ip helper-address vrf name [ global ] address Example: Router config-if ip helper-address vrf blue Configuring Support for Relay Agent Information Option Encapsulation When two relay agents are relaying messages between the DHCP client and the DHCP server, the relay agent closer to the server, by default, replaces the first option 82 information with its own option The relay agent automatically adds the circuit ID suboption and the remote ID suboption to option 82 and forwards them to the second relay agent.
The gateway IP address giaddr is set to the incoming interface on the second relay agent and the original giaddr from the first relay agent is encapsulated. The DHCP server receives the packet and uses the VPN suboption information from the second relay agent, along with the option 82 information from the first relay agent, to assign IP addresses and other configuration parameters and forwards the packet back to the second relay agent.
When the second relay agent receives the reply message from the server, it restores the encapsulated option 82 and prior giaddr from the first relay agent.
The reply message is then sent to the prior giaddr. The first relay agent strips option 82 off from the packet before forwarding the packet to the client. Figure 2. Option 82 information from both relay agents will be forwarded to the DHCP server. If you configure the global configuration command, there is no need to configure the interface configuration command unless you want to apply a different configuration on a specific interface.
This command has precedence over the global configuration command. Figure 3. Thus, a DHCP relay agent does not receive this message.
Again, a DHCP relay agent does not receive this message. Figure 4. Thus a DHCP relay agent does not receive this message. Thus, all messages related to those procedures are excluded in this appendix. Figure 5. Figure 6. Figure 7. Figure 8. Is it possible to know which editing tool you have used to draw such a beautiful detailed explanaions with respect to protocol?
The source port and destination port used between router and DHCP server must be 67 in both direction. Very informative article!! A quick note though, I think the source port from the relay agent should be 67 itself otherthan 68 whent the relay agent unicasts the packets to the Server. Correct me if i am wrong. I've been surfing internet to get packet level explaination specifially with DHCP Server located on a different network, this is the best explaination I have ever came across.
Thank you too much. Netmanias USA : 36th Ave. All rights reserved. English Korean About Us. HFR, Inc. Download PDF File. Table of Contents I. References [1] W. Awesome article. Haven't seen such a detailed and clear discription of the topic. Netmanias Hi Varun, Thank you for your compliment I ever r seen this much clear explanatioin on dhcp relay agent. Thank you :. Priyanshu This is by far the best explanation i have seen on DHCP..
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