HP 2920 Series User Manual

Similarly, if you want to define specific ranges of addresses for clients on different ports in the
same VLAN, you can configure the server with the range of IP addresses allowed for each circuit
ID (port) associated with the remote ID (IP address) for the selected VLAN.
Forwarding policies
DHCP Option 82 on HP switches offers four forwarding policies, with an optional validation of
server responses for three of the policy types (append, replace, or drop.)
Configuration options for managing DHCP client request packets
DHCP client request packet inbound to the routing switchOption 82
configuration
Packet includes an Option 82 fieldPacket has no
Option 82 field
Append allows the most detail in defining DHCP policy boundaries. For example,
where the path from a client to the DHCP Option 82 server includes multiple relay
Append an
Option 82
field
Append
agents with Option 82 capability, each relay agent can define a DHCP policy
boundary and append its own Option 82 field to the client request packet. The
server can then determine in detail the agent hops the packet took, and can be
configured with a policy appropriate for any policy boundary on the path. Note:
NOTE: In networks with multiple relay agents between a client and an Option
82 server, append can be used only if the server supports multiple Option 82
fields in a client request. If the server supports only one Option 82 field in a request,
consider using the keep option.
If the relay agent receives a client request that already has one or more Option
82 fields, keep causes the relay agent to retain such fields and forward the request
Append an
Option 82
field
Keep
without adding another Option 82 field. But if the incoming client request does
not already have any Option 82 fields, the relay agent appends an Option 82
field before forwarding the request. Some applications for keep include:
• The DHCP server does not support multiple Option 82 packets in a client request,
and there are multiple Option 82 relay agents in the path to the server.
• The unusual case where DHCP clients in the network add their own Option 82
fields to their request packets, and you do not want any additional fields added
by relay agents.
This policy does not include the validate option (described in the next section)
and allows forwarding of all server response packets arriving inbound on the
routing switch (except those without a primary relay agent identifier.)
Replace replaces any existing Option 82 fields from downstream relay agents
(and/or the originating client) with an Option 82 field for the current relay agent.
Some applications for replace include:
Append an
Option 82
field
Replace
• The relay agent is located at a point in the network that is a DHCP policy
boundary, and you want to replace any Option 82 fields appended by
down-stream devices with an Option 82 field from the relay agent at the
boundary. (This eliminates downstream Option 82 fields you do not want the
server to use when determining which IP addressing policy to apply to a client
request.)
• In applications where the routing switch is the primary relay agent for clients
that may append their own Option 82 field, you can use replace to delete
these fields if you do not want them included in client requests reaching the
server.
Drop causes the routing switch to drop an inbound client request with an Option
82 field already appended. If no Option 82 fields are present, drop causes the
Append an
Option 82
field
Drop
routing switch to add an Option 82 field and forward the request. As a general
guideline, configure drop on relay agents at the edge of a network, where an
inbound client request with an appended Option 82 field may be unauthorized,
a security risk, or for some other reason, should not be allowed.
70 IP Routing Features

HP 2920 Series Specifications

General

Model	HP 2920 Series
Stacking	Yes, up to 4 switches
PoE	Optional, depending on the model (PoE+)
Routing	Static, RIP, OSPF
Management	Web interface, CLI, SNMP
Features	IPv6 support, ACLs, QoS, sFlow
Power Consumption	Varies by model
Weight	Varies by model
Operating Temperature	0°C to 45°C (32°F to 113°F)
Operating Humidity	15% to 95% non-condensing
Ports	24 or 48 x 10/100/1000 ports
Dimensions	1U height, 17.3 x 10.2 x 1.7 in (44 x 26 x 4.3 cm)

Summary

1 Multimedia Traffic Control with IP Multicast (IGMP)

Overview

Introduces multimedia traffic control using IGMP for bandwidth reduction.

IGMP general operation and features

Explains how IGMP reduces bandwidth usage and its applications.

IGMP operating features

Details IGMP configuration options and basic operation.

Operation with or without IP addressing

Compares IGMP operation when the VLAN has or lacks an IP address.

Querier capability

Explains the switch's role as a querier when no other device is available.

Configuring and displaying IGMP (CLI)

Details CLI commands for IGMP configuration and status display.

Viewing IGMP configuration for VLANs

Shows CLI syntax to display IGMP config for specific or all VLANs.

Viewing the current IGMP configuration

Details CLI commands for viewing global and per-VLAN IGMP configuration.

Viewing IGMP high level statistics for all VLANs on the switch

Provides CLI command to view IGMP statistics across all VLANs.

Viewing IGMP historical counters for a VLAN

Shows CLI command to view historical IGMP counters for a specific VLAN.

Viewing IGMP group address information

Provides CLI command to display IGMP group address information.

Viewing IGMP group information for a VLAN with a filtered address

Details CLI command to view IGMP group info for a VLAN and specific IP address.

Enabling or disabling IGMP on a VLAN

Explains CLI commands to enable or disable IGMP on a VLAN.

Configuring per-port IGMP traffic filters

Configures how each port handles IGMP traffic (auto, blocked, forward).

Configuring the querier function

Enables or disables the switch's ability to act as an IGMP querier.

Configuring static multicast groups

Creates IGMP static groups for forwarding multicast traffic.

How IGMP operates

Explains IGMP's role in managing multicast groups with Query, Report, and Leave messages.

Operation with or without IP addressing

Compares IGMP operation when the VLAN has or lacks an IP address.

Automatic fast-leave IGMP

Details how fast-leave is handled by different switch models.

Default (enabled) IGMP operation solves the "delayed leave" problem

Explains how default IGMP handles multicast traffic after a leave message.

Configuring fast-leave IGMP

Configures IGMP fast-leave on specified ports using CLI commands.

Configuring forced fast-leave IGMP

Enables forced fast-leave IGMP on specified ports for cascaded connections.

Configuring fast learn

Enables fast learn for faster multicast convergence after topology changes.

Configuring delayed group flush

Configures a delay for flushing IGMP groups after leaves are sent.

IGMP proxy forwarding

How IGMP proxy forwarding works

Illustrates how IGMP joins are propagated across router boundaries.

Configuring IGMP proxy (CLI)

Adding or leaving a multicast domain

Describes CLI commands to add or remove an IGMP proxy domain.

VLAN context command

Associates VLANs with IGMP proxy domains for handling joins.

IGMP proxy show command

Shows active IGMP proxy entries, domains, or VLANs.

Using the switch as querier

Well-known or reserved multicast addresses excluded from IP multicast filtering

Reserved addresses excluded from IP multicast filtering

Details multicast address ranges always flooded due to being reserved.

IP multicast filters

2 Multimedia Traffic Control with IP Multicast (IGMP) v2 NG

IGMP V2 NG Overview

Introduces IGMP v2 NG, its architecture, and features.

Features overview

Lists existing and new features supported by IGMP v2 NG.

IGMP Context Commands

CLI commands for configuring IGMP.

Enabling delayed flush on IGMP

Configures delayed flush timeout for IGMP on all VLANs.

Configuring Fast-Learn IGMP

Enables fast learn feature globally for faster convergence.

VLAN Context Commands

Commands executed in VLAN context affecting the IgmpInterfaceTable.

Enabling or Disabling IGMP on a VLAN

CLI commands to enable or disable IGMP on a specific VLAN.

Configuring the Querier Function

Enables/disables the switch's ability to act as an IGMP querier.

Configuring the IGMP Query Interval

Sets the query interval for IGMP.

Configuring Per-Port IGMP Traffic Filters

Configures how each port handles IGMP traffic (auto, blocked, forward).

Configuring Fast-Leave IGMP

Enables IGMP fast-leaves on specified ports in a VLAN.

Configuring Forced Fast-Leave IGMP

Enables Forced Fast-Leave IGMP on specified ports, even if cascaded.

Configuring Static Multicast Groups

Creates IGMP static groups on a selected VLAN.

Show Commands

Lists CLI commands for IGMP configuration and status.

Viewing the current IGMP configuration and status

Displays IGMP status for enabled VLANs or a specific VLAN.

Displays IGMP configuration for a specific VLAN on the switch, including per-port data.

Shows IGMP configuration details for a specific VLAN and its ports.

Lists the ports currently joined for a specified group, with port type, port mode, Age Timer data and Leave Timer data. If the group is not specified, all groups are shown.

Displays port information for specified or all IGMP groups in a VLAN.

Displays IGMP group address information.

Shows IGMP group address information, including VLAN ID, address, uptime, reporter, type.

Statistics and State commands

Lists CLI commands for viewing IGMP statistics and state.

Displays IGMP high level statistics for all VLANs on the switch.

Shows aggregated IGMP statistics across all VLANs.

Displays IGMP high level statistics for < vid > VLAN on the switch.

Shows IGMP statistics for a specific VLAN.

Displays IGMP historical counters for <vid> VLAN on the switch.

Retrieves historical IGMP counter data for a specific VLAN.

Help function commands

Lists CLI commands for obtaining IGMP help and status information.

3 IP Routing Features

Overview

Lists the IP routing features offered by the switch.

IP interfaces

Explains IP addresses associated with VLANs and routing interfaces.

IP tables and caches

Discusses IP tables and caches like ARP cache and route table.

ARP cache table

Describes the ARP cache mapping IP to MAC addresses.

IP route table

Explains the IP route table and its sources of routing paths.

IP forwarding cache

Discusses the fast-path mechanism for forwarding IP packets.

IP route exchange protocols

Mentions support for RIP IP route exchange protocol.

IP global parameters for routing switches

Lists global IP parameters and their default values.

Directed broadcast forwarding

Explains forwarding of directed broadcasts and its default state.

ICMP Router Discovery Protocol (IRDP)

Describes IRDP for advertising router interfaces to hosts.

Static route

Defines static routes placed directly in the IP route table.

Default network route

Explains the default route used when no other route is found.

ARP age timer

Configures the time the switch keeps MAC addresses learned via ARP.

IP interface parameters for routing switches

Lists interface-level IP parameters for routing switches.

Configuring IP parameters for routing switches

Details configuration of IP parameters globally and per VLAN.

Configuring ARP parameters

Explains ARP as a standard IP protocol for MAC address acquisition.

How ARP works

Describes the process of obtaining MAC addresses for IP forwarding.

Configuring forwarding parameters

Controls forwarding behavior of HP routing switches.

Enabling forwarding of directed broadcasts

Configures forwarding of IP broadcast packets to devices on a network.

Enabling forwarding of IP directed broadcasts (CLI)

CLI command to enable forwarding of IP directed broadcasts.

Configuring ICMP

Covers ICMP limits like burst-normal and reply limit.

Disabling ICMP messages

Selectively disables ICMP messages like echo or destination unreachable.

Disabling replies to broadcast ping requests

Disables response to broadcast ICMP echo packets.

Disabling ICMP destination unreachable messages

Explains types of ICMP unreachable messages and their disabling.

Disabling all ICMP unreachable messages

Command to disable all ICMP unreachable messages.

Disabling ICMP redirects

Disables ICMP redirects globally on the routing switch.

Configuring static IP routes

Enables creation of static and null routes directly in the route table.

Static route types

Describes standard and null (discard) static route types.

Other sources of routes in the routing table

Lists other sources for routes like directly connected networks and RIP.

Static IP route parameters

Specifies destination network/host, mask, and path for static routes.

Static route states follow VLAN states

Static routes remain active as long as the next-hop interface is up.

Configuring a static IP route

Details how to configure static routes using destination and next-hop information.

Viewing static route information

Displays the current static route configuration on the routing switch.

Configuring the default route

Assigns the default route for traffic not matching other entries.

Configuring ECMP routing for static IP routes

Allows multiple equal-cost paths to the same destination for load-sharing.

Configuring RIP

Outlines how to configure RIP using the CLI interface.

Overview of RIP

Explains RIP as an IP route exchange protocol using distance vectors.

RIP parameters and defaults

Lists RIP parameters, their default values, and configuration info.

RIP global parameters

Details global RIP parameters like state, auto-summary, and metric.

RIP interface parameters

Lists RIP parameters configurable on a per-VLAN interface basis.

Configuring RIP parameters

Procedures for configuring RIP parameters system-wide and per VLAN.

Enabling RIP

Steps to enable RIP routing and set default version.

Enabling RIP on the routing switch and entering the RIP router context

Commands to enable RIP and enter its configuration context.

Enabling IP RIP on a VLAN

Enables RIP for all or specific IP addresses within a VLAN.

Changing the RIP type on a VLAN interface

Changes the RIP version (v1, v2, or both) on a VLAN interface.

Changing the cost of routes learned on a VLAN interface

Modifies the cost (metric) added to RIP routes learned on an interface.

Configuring RIP redistribution

Configures the switch to redistribute connected, static, and OSPF routes into RIP.

Defining RIP redistribution filters

Specifies routes to permit or deny for redistribution based on address or interface.

Configuring for redistribution

Defines redistribution tables using the 'restrict' command.

Modifying default metric for redistribution

Sets a global default metric for all RIP routes.

Enabling RIP route redistribution

Enables redistribution of connected or static routes into RIP.

Changing the route loop prevention method

Configures split horizon or poison reverse for preventing RIP routing loops.

Viewing RIP information

Shows all RIP configuration and status via CLI commands.

Viewing general RIP information

Displays general RIP information, including global parameters and interfaces.

Viewing RIP interface information

Displays RIP interface information, including IP address, status, and mode.

Viewing RIP peer information

Shows information about neighboring routers from which RIP updates are received.

Viewing RIP redistribution information

Displays status of connected and static route redistribution into RIP.

Viewing RIP redistribution filter (restrict) information

Shows any routes being restricted from redistribution via the restrict command.

Configuring IRDP

Explains IRDP for advertising router interfaces to directly attached hosts.

Enabling IRDP globally

Enables IRDP on all IP interfaces with default parameter values.

Enabling IRDP on an individual VLAN interface

Enables IRDP on a specific VLAN interface and configures parameters.

Configuring DHCP relay

Explains DHCP relay for configuring hosts with IP and configuration parameters.

Overview

Explains DHCP relay for configuring hosts with IP and configuration parameters.

DHCP packet forwarding

Discusses how DHCP relay forwards client packets to DHCP servers.

Unicast forwarding

Forwards DHCP packets using unicast when the server is a specific host.

Broadcast forwarding

Forwards DHCP packets using broadcast for subnet or IP broadcast addresses.

Prerequisites for DHCP relay operation

Steps required for the DHCP relay agent to function on the switch.

Enabling DHCP relay

Enables or disables the DHCP relay function on the routing switch.

Configuring an IP helper address

Adds or removes the IP address of a DHCP server for a specified VLAN.

Verifying the DHCP relay configuration

How to view the current DHCP relay settings.

Viewing the DHCP relay setting

Displays current DHCP relay configuration.

Viewing DHCP helper addresses

Displays configured IP Helper addresses for a specified VLAN.

DHCP Option 82

Explains Option 82 for relay agent information in DHCP packets.

Option 82 server support

Discusses requirements for Option 82 support on DHCP servers.

General DHCP Option 82 requirements and operation

Outlines requirements and the operation of DHCP Option 82.

Requirements

Lists prerequisites for Option 82 operation on the switch.

General DHCP-relay operation with Option 82

Describes how Option 82 relay agents handle DHCP requests and responses.

Option 82 field content

Details subfields like Remote ID and Circuit ID in Option 82.

Remote ID

Discusses configurable Remote ID subfields (IP, MAC, mgmt-vlan).

Circuit ID

Explains Circuit ID as the physical port number for DHCP client requests.

Forwarding policies

DHCP Option 82 forwarding policies (append, replace, drop) with validation.

Configuration options for managing DHCP client request packets

Options for managing DHCP client request packets based on Option 82.

Multiple Option 82 relay agents in a client request path

How multiple Option 82 agents contribute fields in a client request path.

Validation of server response packets

How server response validation enhances protection against invalid Option 82 data.

Configuring Option 82

Command syntax for configuring DHCP Option 82 forwarding policies.

Example of Option 82 configuration

Demonstrates configuring Option 82 with mgmt-vlan as the remote ID.

Operating notes

Notes on DHCP relay implementation with Option 82 and RFC compliance.

UDP broadcast forwarding

Explains UDP broadcast forwarding for applications using IP broadcasts.

Overview

Explains UDP broadcast forwarding for applications using IP broadcasts.

Subnet masking for UDP forwarding addresses

How subnet masks apply to UDP forwarding addresses.

Configuring and enabling UDP broadcast forwarding

Steps to configure and enable UDP broadcast forwarding.

Globally enabling UDP broadcast forwarding

Command to globally enable UDP broadcast forwarding.

Configuring UDP broadcast forwarding on individual VLANs

Routes inbound UDP broadcast packets on a VLAN to specific addresses.

Operating notes for UDP broadcast forwarding

Notes on UDP broadcast entry limits and TCP/UDP port number ranges.

Maximum number of entries

Details the limits on UDP broadcast entries and IP helper addresses.

TCP/UDP port number ranges

Lists the ranges for well-known, registered, and dynamic ports.

Messages related to UDP broadcast forwarding

Explains messages related to UDP broadcast forwarding status.