Reference Guide

Parameter Definition
Maximum Hop Count The maximum allowable relay agent hops.
Minimum Wait Time
(Seconds)
The minimum wait time.
Admin Mode Whether relaying of requests is enabled or disabled.
Circuit Id Option
Mode
The DHCP circuit Id option which may be enabled or disabled.
The following shows an example of the command.
(Extreme 220) (Routing) #show ip bootpdhcprelay
Maximum Hop Count.............................. 4
Minimum Wait Time(Seconds)..................... 0
Admin Mode..................................... Disable
Circuit Id Option Mode......................... Enable
IP Helper Commands
This section describes the commands to configure and monitor the IP Helper agent. IP Helper relays
DHCP and other broadcast UDP packets from a local client to one or more servers which are not on the
same network at the client.
The IP Helper feature provides a mechanism that allows a router to forward certain configured UDP
broadcast packets to a particular IP address. This allows various applications to reach servers on
nonlocal subnets, even if the application was designed to assume a server is always on a local subnet
and uses broadcast packets (with either the limited broadcast address 255.255.255.255, or a network
directed broadcast address) to reach the server.
The network administrator can configure relay entries both globally and on routing interfaces. Each
relay entry maps an ingress interface and destination UDP port number to a single IPv4 address (the
helper address). The network administrator may configure multiple relay entries for the same interface
and UDP port, in which case the relay agent relays matching packets to each server address. Interface
configuration takes priority over global configuration. That is, if a packet’s destination UDP port matches
any entry on the ingress interface, the packet is handled according to the interface configuration. If the
packet does not match any entry on the ingress interface, the packet is handled according to the global
IP helper configuration.
The network administrator can configure discard relay entries, which direct the system to discard
matching packets. Discard entries are used to discard packets received on a specific interface when
those packets would otherwise be relayed according to a global relay entry. Discard relay entries may
be configured on interfaces, but are not configured globally.
In addition to configuring the server addresses, the network administrator also configures which UDP
ports are forwarded. Certain UDP port numbers can be specified by name in the UI as a convenience,
but the network administrator can configure a relay entry with any UDP port number. The network
administrator may configure relay entries that do not specify a destination UDP port. The relay agent
relays assumes these entries match packets with the UDP destination ports listed in Table 12. This is the
list of default ports.
Routing Commands
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