Owner manual
Table Of Contents
- Contents
- Figures
- Tables
- Preface
- Section I
- Basic Operations
- Chapter 1
- Overview
- Chapter 2
- Enhanced Stacking
- Chapter 3
- SNMPv1 and SNMPv2c
- Chapter 4
- MAC Address Table
- Chapter 5
- Static Port Trunks
- Chapter 6
- LACP Port Trunks
- Chapter 7
- Port Mirror
- Section II
- Advanced Operations
- Chapter 8
- File System
- Chapter 9
- Event Logs and the Syslog Client
- Chapter 10
- Classifiers
- Chapter 11
- Access Control Lists
- Chapter 12
- Class of Service
- Chapter 13
- Quality of Service
- Chapter 14
- Denial of Service Defenses
- Chapter 15
- Power Over Ethernet
- Section III
- Snooping Protocols
- Chapter 16
- IGMP Snooping
- Chapter 17
- MLD Snooping
- Chapter 18
- RRP Snooping
- Chapter 19
- Ethernet Protection Switching Ring Snooping
- Section IV
- SNMPv3
- Chapter 20
- SNMPv3
- Section V
- Spanning Tree Protocols
- Chapter 21
- Spanning Tree and Rapid Spanning Tree Protocols
- Chapter 22
- Multiple Spanning Tree Protocol
- Section VI
- Virtual LANs
- Chapter 23
- Port-based and Tagged VLANs
- Chapter 24
- GARP VLAN Registration Protocol
- Chapter 25
- Multiple VLAN Modes
- Chapter 26
- Protected Ports VLANs
- Chapter 27
- MAC Address-based VLANs
- Section VII
- Routing
- Chapter 28
- Internet Protocol Version 4 Packet Routing
- Supported Platforms
- Overview
- Routing Interfaces
- Interface Names
- Static Routes
- Routing Information Protocol (RIP)
- Default Routes
- Equal-cost Multi-path (ECMP) Routing
- Routing Table
- Address Resolution Protocol (ARP) Table
- Internet Control Message Protocol (ICMP)
- Routing Interfaces and Management Features
- Local Interface
- AT-9408LC/SP AT-9424T/GB, and AT-9424T/SP Switches
- Routing Command Example
- Non-routing Command Example
- Upgrading from AT-S63 Version 1.3.0 or Earlier
- Chapter 29
- BOOTP Relay Agent
- Chapter 30
- Virtual Router Redundancy Protocol
- Section VIII
- Port Security
- Chapter 31
- MAC Address-based Port Security
- Chapter 32
- 802.1x Port-based Network Access Control
- Section IX
- Management Security
- Chapter 33
- Web Server
- Chapter 34
- Encryption Keys
- Chapter 35
- PKI Certificates and SSL
- Chapter 36
- Secure Shell (SSH)
- Chapter 37
- TACACS+ and RADIUS Protocols
- Chapter 38
- Management Access Control List
- Appendix A
- AT-S63 Management Software Default Settings
- Address Resolution Protocol Cache
- Boot Configuration File
- BOOTP Relay Agent
- Class of Service
- Denial of Service Defenses
- 802.1x Port-Based Network Access Control
- Enhanced Stacking
- Ethernet Protection Switching Ring (EPSR) Snooping
- Event Logs
- GVRP
- IGMP Snooping
- Internet Protocol Version 4 Packet Routing
- MAC Address-based Port Security
- MAC Address Table
- Management Access Control List
- Manager and Operator Account
- Multicast Listener Discovery Snooping
- Public Key Infrastructure
- Port Settings
- RJ-45 Serial Terminal Port
- Router Redundancy Protocol Snooping
- Server-based Authentication (RADIUS and TACACS+)
- Simple Network Management Protocol
- Simple Network Time Protocol
- Spanning Tree Protocols (STP, RSTP, and MSTP)
- Secure Shell Server
- Secure Sockets Layer
- System Name, Administrator, and Comments Settings
- Telnet Server
- Virtual Router Redundancy Protocol
- VLANs
- Web Server
- Appendix B
- SNMPv3 Configuration Examples
- Appendix C
- Features and Standards
- 10/100/1000Base-T Twisted Pair Ports
- Denial of Service Defenses
- Ethernet Protection Switching Ring Snooping
- Fiber Optic Ports (AT-9408LC/SP Switch)
- File System
- DHCP and BOOTP Clients
- Internet Protocol Multicasting
- Internet Protocol Version 4 Routing
- MAC Address Table
- Management Access and Security
- Management Access Methods
- Management Interfaces
- Management MIBs
- Port Security
- Port Trunking and Mirroring
- Spanning Tree Protocols
- System Monitoring
- Traffic Control
- Virtual LANs
- Virtual Router Redundancy Protocol
- Appendix D
- MIB Objects
- Index
AT-S63 Management Software Features Guide
Section VII: Routing 339
Overview
The AT-S63 Management Software comes with a BOOTP relay agent for
relaying BOOTP messages between clients and DHCP or BOOTP
servers.
When a client sends a BOOTP request to a DHCP or BOOTP server for an
IP configuration, it transmits the request as a broadcast packet because it
does not know the IP address of the server. This can present a problem
when a client and server reside on different subnets, because broadcast
packets do not cross subnet boundaries. One possible solution is to have
a DHCP or BOOTP server on each subnet where there are clients, though
this could be problematic if there happen to be a lot of subnets. Another
solution is to use a BOOTP relay agent, which transfers client requests
across subnet boundaries.
The BOOTP relay agent does more than simply forward BOOTP requests
from clients to servers. It modifies the requests so that, from the
perspective of the server, it becomes the originator of the request. The
responses from the servers are directed to the agent, which sends the
messages on to the clients as either broadcast or unicast packets,
depending on the requirements of the clients.
To implement BOOTP relay on the switch, you need to be familiar with
routing interfaces, which route packets between different local subnets on
the switch in the IPv4 packet routing feature. Each routing interface
functions as the BOOTP relay agent for the clients in its subnet, forwarding
BOOTP requests from the clients and responses from the servers.
If you will be using the IPv4 packet routing feature on all the local subnets,
then, by default, all of the clients will have access to a BOOTP relay agent
because each subnet will have a routing interface. However, if IPv4 packet
routing will be limited to some but not all the local subnets of the switch,
then only those BOOTP requests from clients on a subnet with a routing
interface will be forwarded to a BOOTP relay agent.
Here is an overview of the process. When a routing interface receives a
BOOTP request with a value of 0.0.0.0 in the gateway (giaddr) field in the
packet, it assumes the request originated from a client on its subnet. In
response, it replaces the value in the field with its IP address and forwards
the packet on to the server. If more than one IP address of DHCP or
BOOTP servers are specified on the switch, the interface sends the same
request to each server. If the client and server reside on the same subnet,
the routing interface does not forward the request.
If an interface receives a BOOTP request with a non-zero value in the
gateway field, it assumes the client who originated the request resides on
another subnet, and so routes the request as a unicast packet without any
change, other than incrementing the hop count.