To Next Page

To Previous Page

Reviewing IP Traffic and Configuring Routes

SecureStack C2 Configuration Guide 16-13

Usage

WhenahostrequestsanIPaddress,itsendsoutaDHCPbroadcastpacket.Normally,therouter

dropsallbroadcastpackets.However,byexecutingthiscommand,youenabletherouted

interfacetopassDHCPbroadcastframesthrough,sendingthemdirectlytotheremoteDHCP

server’sIPaddress.

TheDHCP/BOOTPrelayagent

willdetectDHCP/BOOTPrequestsbasedonUDPsourceand

destinationports.Itwillthenmakethenecessarychangestothepacketandsendthepackettothe

DHCPserver.Thechangesinclude:

•ReplacingthedestinationIPaddresswiththeaddressoftheDHCPserver,

•ReplacingthesourceIPaddresswithits

ownaddress(thatis,theIPaddressofthelocal

routedinterface),and

•WithintheBOOTPpartofthepacket,changingtheRelayAgentIPaddressfrom0.0.0.0tothe

addressofthelocalroutedinterface.

ThelastchangetotheBootPpacket“tells”theDHCPserverthatitneedsto

assignanIPaddress

thatisinthesamesubnetastheRelayAgentIP.Whentheresponsecomesfromtheserver,the

DHCP/BOOTPrelayagentsendsittothehost.

Example

ThisexampleshowhowtohaveallclientDHCPrequestsforusersinVLAN1tobeforwardedto

theremoteDHCPserverwithIPaddress192.168.1.28.

C2(su)->router(Config)#interface vlan 1

C2(su)->router(Config-if(Vlan 1))#ip helper-address 192.168.1.28

Reviewing IP Traffic and Configuring Routes

Purpose

ToreviewIPtrafficandconfigureroutes,tosendrouterICMP (ping)messages,andtoexecute

traceroute.

Commands

show ip route

UsethiscommandtodisplayinformationaboutIProutes.

Syntax

show ip route [destination-prefix destination-prefix-mask longer-prefixes |

connected | ospf | rip | static | summary]

For information about... Refer to page...

show ip route 16-13

ip route 16-14

ping 16-15

traceroute 16-16

Enterasys SecureStack C2 User Manual

Questions and Answers: