Juniper EX3400 Features Guide

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Interaction Among the DHCP Relay Agent, DHCP Client, and DHCP Servers on page 47
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DHCP Liveness Detection on page 48
Interaction Among the DHCP Relay Agent, DHCP Client, and DHCP Servers
The pattern of interaction among the DCHP Relay agent, DHCP client, and DHCP servers
is the same regardless of whether the software installation is on a router or a switch.
However, there are some difference in the details of usage.
On routers—In a typical carrier edge network configuration, the DHCP client is on the
subscriber’s computer, and the DHCP relay agent is configured on the router between
the DHCP client and one or more DHCP servers.
On switches—In a typical network configuration, the DHCP client is on an access device
such as a personal computer and the DHCP relay agent is configured on the switch
between the DHCP client and one or more DHCP servers.
The following steps describe, at a high level, how the DHCP client, DHCP relay agent,
and DHCP server interact in a configuration that includes two DHCP servers.
1. The DHCP client sends a discover packet to find a DHCP server in the network from
which to obtain configuration parameters for the subscriber (or DHCP client), including
an IP address.
2. The DHCP relay agent receives the discover packet and forwards copies to each of
the two DHCP servers. The DHCP relay agent then creates an entry in its internal client
table to keep track of the client’s state.
3. In response to receiving the discover packet, each DHCP server sends an offer packet
to the client. The DHCP relay agent receives the offer packets and forwards them to
the DHCP client.
4. On receipt of the offer packets, the DHCP client selects the DHCP server from which
to obtain configuration information. Typically, the client selects the server that offers
the longest lease time on the IP address.
5. The DHCP client sends a request packet that specifies the DHCP server from which
to obtain configuration information.
6. The DHCP relay agent receives the request packet and forwards copies to each of the
two DHCP servers.
7. The DHCP server requested by the client sends an acknowledgement (ACK) packet
that contains the client’s configuration parameters.
8. The DHCP relay agent receives the ACK packet and forwards it to the client.
9. The DHCP client receives the ACK packet and stores the configuration information.
10. If configured to do so, the DHCP relay agent installs a host route and Address
Resolution Protocol (ARP) entry for this client.
11. After establishing the initial lease on the IP address, the DHCP client and the DHCP
server use unicast transmission to negotiate lease renewal or release. The DHCP relay
agent “snoops” on all of the packets unicast between the client and the server that
47Copyright © 2017, Juniper Networks, Inc.
Chapter 4: DHCP Relay Agent

Juniper EX3400 Specifications

General

Switch type	Managed
Switch layer	L2/L3
Quality of Service (QoS) support	Yes
Safety	UL-UL60950-1, C-UL CAN/CSA 22.2 No.60950-1, TUV/GS to EN 60950-1, CB-IEC60950-1, EN 60825-1
Form factor	1U
Product color	Black
Electromagnetic compatibility	FCC 47CFR 15 A, EN 55022 A, ICES-003 A, VCCI A, AS/NZS CISPR 22 A, CISPR 22 A, EN 55024, EN 300386, CE
SFP+ module slots quantity	4
QSFP+ module slots quantity	2
Installed SFP+ modules quantity	0
Basic switching RJ-45 Ethernet ports type	Gigabit Ethernet (10/100/1000)
Basic switching RJ-45 Ethernet ports quantity	48
Memory type	DRAM
Noise level	35 dB
Flash memory	2000 MB
Processor frequency	1000 MHz
Virtual stacking (units)	10
Throughput	250 Mpps
Jumbo frames	9216
MAC address table	32000 entries
Number of VLANs	4093
Networking standards	IEEE 802.1D, IEEE 802.1Q, IEEE 802.1ab, IEEE 802.1p, IEEE 802.1s, IEEE 802.1w, IEEE 802.1x, IEEE 802.3, IEEE 802.3ab, IEEE 802.3ad, IEEE 802.3ae, IEEE 802.3u, IEEE 802.3z
Virtual LAN features	Port-based VLAN
Copper ethernet cabling technology	10BASE-T, 100BASE-T, 1000BASE-T
Power consumption (max)	120 W
Number of power supply units	1
Operating altitude	0 - 3048 m
Non-operating altitude	3048 - 4877 m
Storage temperature (T-T)	-40 - 70 °C
Operating temperature (T-T)	0 - 45 °C
Storage relative humidity (H-H)	0 - 95 %
Operating relative humidity (H-H)	10 - 85 %
DHCP features	DHCP server, DHCP client
Authentication	MAC-based authentication, Port-based authentication
Security algorithms	802.1x RADIUS, HTTPS, SNMP, SSH-2
Fiber ethernet cabling technology	1000BASE-X

Weight and Dimensions

Depth	350 mm
Width	437 mm
Height	44 mm
Weight	5740 g