show dhcp relay statistics - TechLibrary - Juniper Networks
Trying to capture DHCP packets (discover, offer, request See the DHCP RFC (https://www.ietf.org/rfc/rfc2131.txt) for info about when unicast and broadcast addresses are valid. A switch only sends packets out a port that are either addressed to the attached device or to the broadcast address. Any DHCP packets being sent to the bulb MAC addresses won't be sent to the desktop switch port. Packet Captures - PacketLife.net Aug 28, 2015 How does a router relay DHCP packets when it is configured Normally, DHCP servers and BOOTP relay agents attempt to deliver DHCPOFFER, DHCPACK and DHCPNAK messages directly to the client using uicast delivery. The IP destination address (in the IP header) is set to the DHCP 'yiaddr' address and the link-layer destination address is set to the DHCP 'chaddr' address. Configuring DHCPv6 (both stateless and stateful) in Packet
Trying to capture DHCP packets (discover, offer, request
Nov 17, 2008
DHCP - The Wireshark Wiki
Aug 28, 2015 · DHCP_Inter_VLAN.cap 2.0 KB. Submitted Sep 30, 2009 by pierky. R1 is a router-on-a-stick. It receives a DHCP Discover on the trunk interface, it sets the "Relay agent IP address" to the sub-interface's IP address it received the packet on and, finally, it forwards it to the DHCP server. Capture perspective is R1-DHCP server link. BOOTP Ethernet No. Time Source Destination Protocol Length Info; 1: 0.000000: 0.0.0.0: 255.255.255.255: DHCP: 618: DHCP Discover - Transaction ID 0x155c: 2: 2.047000: 192.168.0.1 Nov 05, 2019 · Lastly, activate stateful DHCPv6 on interface fa0/0 of the router using ipv6 dhcp server command using the name of the DHCP pool . This interface will become the DHCPv6 server . This is a bit different from IPv4 (since here we’re activating DHCPv6 on a router interface) A DHCP relay agent forwards a DHCP packet that includes a relay-agent IP address that is not 0.0.0.0, or the relay agent forwards a packet that includes option-82 information to an untrusted port. As I indicated, however, I personally discourage running the DHCP Snooping on core devices - I see no reason for that. I'd like to capture DHCP packets with wireshark. When I use the filter: "udp.port == 67 or udp.port == 68" I only see the Discover and Request broadcasts. While I thought the DHCP offer also gets broadcasted. I'm running wireshark on another machine then the machine which requests the ip but am connected to the same network. With DHCP Filter configured, the switch can check whether the received DHCP packets are legal and discard the illegal ones. In this way, DHCP Filter ensures that users get IP addresses only from the legal DHCP server and enhances the network security. As the following figure shows, there are both legal and illegal DHCP servers on the network. interface FastEthernet0/1 ip address dhcp Now let's take a look at some packet captures - Traffic between R1 & R2: Traffic between R2 & PC: So you see, the traffic between R1 and R2 is unicast (as you'd expect) and the traffic between R2 and PC is broadcast, the same way as it would be if R2 were the DHCP server.