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ip helper-address
16-12
IP Configuration
Defaults
None.
Mode
Interface
configuration:
C2(su)
‐
>Router1(Config
‐
if(Vlan
1))#
Usage
Directed
broadcast
is
an
efficient
mechanism
for
communicating
with
multiple
hosts
on
a
network
while
only
transmitting
a
single
datagram.
A
directed
broadcast
is
a
packet
sent
to
all
hosts
on
a
specific
network
or
subnet.
The
directed
broadcast
address
includes
the
network
or
subnet
fields,
with
the
binary
bits
of
the
host
portion
of
the
address
set
to
one.
For
example,
for
a
network
with
the
address
192.168.0.0,
the
directed
broadcast
address
would
be
192.168.255.255.
For
a
subnet
with
the
address
192.168.12.0,
the
directed
broadcast
address
would
be
192.168.12.255.
In
order
to
minimize
broadcast
DoS
attacks,
forwarding
of
directed
broadcasts
is
disabled
by
default
on
the
SecureStack
C2,
as
recommended
by
RFC
2644.
If
the
ability
to
send
directed
broadcasts
to
a
network
is
required,
you
should
enable
directed
broadcasts
only
on
the
one
interface
that
will
be
transmitting
the
datagrams.
For
example,
if
a
SecureStack
C2
has
five
routed
interfaces
for
the
10,
20,
30,
40,
and
50
networks,
enabling
directed
broadcast
only
on
the
30
network
interface
will
allow
anyone
from
any
other
networks
(10,
20,
40,
50)
to
send
directed
broadcast
to
the
30
network.
Example
This
example
shows
how
to
enable
IP
directed
broadcasts
on
VLAN
1:
C2(su)->router(Config)#interface vlan 1
C2(su)->router(Config-if(Vlan 1))#ip directed-broadcast
ip helper-address
Use
this
command
to
enable
the
DHCP/BOOTP
relay
agent
on
a
SecureStack
C2
routed
interface.
Enabling
the
relay
agent
allows
forwarding
of
client
DHCP/BOOTP
requests
to
a
DHCP/BOOTP
server
that
does
not
reside
on
the
same
broadcast
domain
as
the
client.
Up
to
6
IP
helper
addresses
may
be
configured
per
interface.
The
no
form
of
this
command
disables
the
forwarding
of
UDP
datagrams
to
the
specified
address.
Syntax
ip helper-address address
no ip helper-address address
Parameters
Defaults
None.
Mode
Interface
configuration:
C2(su)
‐
>Router1(Config
‐
if(Vlan
1))#
address
Address
of
the
host
where
UDP
broadcast
packets
should
be
forwarded.
Содержание SecureStack C2
Страница 1: ...SecureStack C2 Stackable Switches Configuration Guide Firmware Version 5 1 xx P N 9033991 16 ...
Страница 2: ......
Страница 28: ...xxvi ...
Страница 106: ...set ssl 3 52 Basic Configuration ...
Страница 226: ...Creating a Basic SNMP Trap Configuration 6 38 SNMP Configuration ...
Страница 278: ...show spantree nonforwardingreason 7 52 Spanning Tree Configuration ...
Страница 302: ...set garp timer 8 24 802 1Q VLAN Configuration ...
Страница 448: ...show dhcp pool configuration 14 30 DHCP Server Configuration ...
Страница 454: ...no license advanced 15 6 Preparing for Router Mode ...