• Tag : dhcp

 
 

DHCP Snooping

EOS supports the DHCP Relay feature, which relays DHCP Requests/Responses between DHCP clients and DHCP servers in different subnets. However, the DHCP server does not have visibility of where the request originated from and can only make IP address allocation decisions based on the client MAC address alone (client MAC address is included in the DHCP packet as part of the payload). To remedy that, DHCP Option-82 was formalized to allow relay agents to include Remote ID and Circuit ID so that DHCP servers can apply a more intelligent allocation policy.Switch intercepts DHCP requests from the client and inserts Option-82...
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DHCP Relay

Introduction DHCP Relay feature forwards DHCP packets between client and server when the DHCP Server is not in the same broadcast domain as the client. DHCP Relay should be configured on the gateway interface (SVI/ L3 interface ) for the clients. DHCP Relay agent creates a new unicast DHCP packet and sets the giaddr field to the ‘primary’ IP address of the interface on which DHCP request packet is received. The modified request packet is then relayed to one or more configured DHCP servers. DHCP server assigns ip address to client from the pool corresponding to giaddr field. Platform Compatibility...
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DHCP relay all subnets

Description EOS DHCP relay agent forwards all the DHCP requests from the clients using the primary IP address of the interface as the ‘giaddr’ in the relayed/forwarded requests even when there are secondary IP addresses configured on the interface and there are multiple IP address pools from secondary IP subnets with available addresses on the server. DHCP Relay All Subnets feature supports forwarding requests with secondary IP addresses in the gateway address ‘giaddr’ field. This allows the DHCP server to offer addresses to client requests with gateway addresses from secondary IP subnets configured on the interface. While All Subnets is...
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Add DHCP to a VLAN

I am trying to add a DHCP server to a switch (config in text). The DHCP server is not responding on the VLAN interface. Does anyone know a way to resolve this? “show dhcp” server gives the following:   IPv4 DHCP server is inactive DNS server(s): 8.8.8.8 Lease duration: 0 days 2 hours 0 minutes Active leases: 0 IPv4 DHCP interface status: Interface Status ————— —— Subnet: 10.10.8.0/22 Range: 10.10.8.101 to 10.10.8.149 DNS server(s): 8.8.8.8 Default gateway address: 10.10.8.1 Active leases: 0

IP Locking + Release Updates

Description IP Locking is an EOS feature configured on an Ethernet Layer 2 port.  When enabled, it ensures that a port will only permit IP and ARP packets with IP source addresses that have been authorized. As of EOS-4.25.0F release update, IP locking can run in two modes – IPv4 Locking (which will be referred to as IP Locking) and IPv6 Locking, which can be configured using the commands mentioned in the below sections. IP Locking prevents another host on a different interface from claiming ownership of an IP address through either IP or ARP spoofing. Additionally, IP Locking prevents...
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DHCP server option 43

I’m working on a campus switch model 720XP in my lab.  It being used as a DHCP server for several subnets, one of which is wireless APs.  I can’t figure out how to get the switch’s DHCP server to dish out an option 43 value to the DHCP clients on the AP subnet so the APs can find the controller.  In this case, I’m using Ruckus APs with a virtual SmartZone controller.   Has anyone ever done this before with an Arista switch?  I can’t find any clear documentation on how to implement option 43.

IP Locking + Release Updates

IP Locking + Release Updates Description IP Locking is an EOS feature configured on an Ethernet Layer 2 port.  When enabled, it ensures that a port will only permit IP and ARP packets with IP source addresses that have been authorized. IP Locking prevents another host on a different interface from claiming ownership of an IP address through ARP spoofing. On an IP Locked Port, ARP probes with 0.0.0.0 as Sender Protocol Address (SPA) will be allowed for duplicate address detection (DAD). Incoming DHCP server response packets are dropped to avoid rogue device(s) acting as DHCP server(s). Incoming DHCP client...
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DHCP Server on Arista EOS

Overview In this document, a DHCP server will be installed on the switch, and configured to deliver IP addresses for a subnet/VLAN interface on the switch serving both IPv4 and IPv6 address families. All examples are demonstrated on Arista EOS release 4.20.7M. Please note that as of EOS 4.22.1, EOS can natively run a DHCP server – this extension and procedure are NOT NECESSARY. Install the DHCPD extension An extension is a Red Hat Linux .rpm file type or an archive of .rpm files in a .swi format. For this example the latest .swi package for DHCPD is downloaded from...
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Support “redistribute dhcp” for IS-IS Agent (IPv6)

Description EOS 4.23.0F adds support for redistributing DHCPv6 routes in IS-IS when using the multi-agent routing protocol mode. Support for this feature in single agent mode has existed since EOS 4.21.0 Configuration DHCPv6 routes can be redistributed into IS-IS via following CLI in only IPv6 address-family mode. Arista(config)#router isis A Arista(config-router-isis)#address-family ipv6 Arista(config-router-isis-af)#redistribute dhcp Show Commands DHCPv6 routes redistributed into IS-IS can be seen in show isis database detail show command # show isis database detail IS-IS Instance: inst1 VRF: default IS-IS Level 1 Link State Database LSPID Seq Num Cksum Life IS Flags 1111.1111.1001.00-00 10 19778 1101 L1 <>...
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IP Locking + Release Updates

Description IP Locking is an EOS feature configured on an Ethernet Layer 2 port.  When enabled, it ensures that a port will only permit IP and ARP packets with IP source addresses that have been authorized. IP Locking prevents another host on a different interface from claiming ownership of an IP address through ARP spoofing. On an IP Locked Port, ARP probes with 0.0.0.0 as Sender Protocol Address (SPA) will be allowed for duplicate address detection (DAD). Incoming DHCP server response packets are dropped to avoid rogue device(s) acting as DHCP server(s). Incoming DHCP client request packets are allowed for...
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DhcpRelay agent source-address option

Introduction: DHCP relay agent uses one of the addresses configured on the interface as the source IP when relaying messages to the DHCP server. DHCP clients will acquire an address in this subnet. If an interface has multiple addresses configured and it is intended for DHCP clients to acquire addresses in a specific subnet, this particular address can be specified as the source-address for the DHCP server. DhcpRelay agent will use this address as the source IP and update the giaddr and link-address when relaying messages to the corresponding server. Release Updates EOS-4.24.0F Added support for CLI option to configure...
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DHCP Snooping and MLAG interfaces

I have a vlan that I want to allocate IP addresses to the hosts based on their switch port-number so that the machines will get a consistent IP address based on their physical location in our cluster. The interface that this vlan is presented to the host is running as an MLAG. The Circuit ID gets correctly inserted as switchname:PortChannelxxx but which switchname will be sent is not clear. Any advice on how to make this configuration work reliably (we can only have one circuit ID in the DHCP configuration)? Should I only run dhcp snooping on one of the...
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DHCP option for ZTP script by HTTP

I am using ISC-DHCP server, and currently serving the ZTP script using TFTP.  I would like to serve the ZTP script using HTTP instead.  What are the proper DCHP options needed to set this up correctly? Thank you!

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