User`s guide
Table Of Contents
- Title
- Notice
- Contents
- Figures
- Tables
- About This Guide
- Introduction
- Local Management Requirements
- Accessing Local Management
- 3.1 Navigating Local Management Screens
- 3.2 Password Screen
- 3.3 Main Menu Screen
- 3.4 Module Selection Screen
- 3.5 Module Menu Screen
- 3.6 Overview of Security Methods
- 3.7 Security Menu Screen
- 3.8 Passwords Screen
- 3.9 Radius Configuration Screen
- 3.10 Name Services Configuration Screen
- 3.11 System Authentication Configuration Screen
- 3.12 EAP (Port) Configuration Screen
- 3.13 EAP Statistics Menu Screen
- 3.14 MAC Port Configuration Screen
- 3.15 MAC Supplicant Configuration Screen
- Chassis Menu Screens
- 4.1 Chassis Menu Screen
- 4.2 Chassis Configuration Screen
- 4.3 SNMP Configuration Menu Screen
- 4.4 SNMP Community Names Configuration Screen
- 4.5 SNMP Traps Configuration Screen
- 4.6 Chassis Environmental Information Screen
- 4.7 Redirect Configuration Menu Screen (Chassis)
- 4.8 Port Redirect Configuration Screen
- 4.9 VLAN Redirect Configuration Screen
- Module Configuration Menu Screens
- 5.1 Module Configuration Menu Screen
- 5.2 General Configuration Screen
- 5.2.1 Setting the IP Address
- 5.2.2 Setting the Subnet Mask
- 5.2.3 Setting the Default Gateway
- 5.2.4 Setting the TFTP Gateway IP Address
- 5.2.5 Setting the Module Name
- 5.2.6 Setting the Module Date
- 5.2.7 Setting the Module Time
- 5.2.8 Entering a New Screen Refresh Time
- 5.2.9 Setting the Screen Lockout Time
- 5.2.10 Configuring the COM Port
- 5.2.11 Clearing NVRAM
- 5.2.12 Enabling/Disabling IP Fragmentation
- 5.3 SNMP Configuration Menu Screen
- 5.4 SNMP Community Names Configuration Screen
- 5.5 SNMP Traps Configuration Screen
- 5.6 Access Control List Screen
- 5.7 System Resources Information Screen
- 5.8 FLASH Download Configuration Screen
- Port Configuration Menu Screens
- 6.1 Port Configuration Menu Screen
- 6.2 Ethernet Interface Configuration Screen
- 6.3 Ethernet Port Configuration Screen
- 6.4 HSIM/VHSIM Configuration Screen
- 6.5 Redirect Configuration Menu Screen
- 6.6 Port Redirect Configuration Screen
- 6.7 VLAN Redirect Configuration Screen
- 6.8 Link Aggregation Screen (802.3ad Main Menu Screen)
- 6.9 Broadcast Suppression Configuration Screen
- 802.1 Configuration Menu Screens
- 802.1Q VLAN Configuration Menu Screens
- 8.1 Summary of VLAN Local Management
- 8.2 802.1Q VLAN Configuration Menu Screen
- 8.3 Static VLAN Configuration Screen
- 8.4 Static VLAN Egress Configuration Screen
- 8.5 Current VLAN Configuration Screen
- 8.6 Current VLAN Egress Configuration Screen
- 8.7 VLAN Port Configuration Screen
- 8.8 VLAN Classification Configuration Screen
- 8.9 Protocol Port Configuration Screen
- 802.1p Configuration Menu Screens
- 9.1 802.1p Configuration Menu Screen
- 9.2 Port Priority Configuration Screen
- 9.3 Traffic Class Information Screen
- 9.4 Traffic Class Configuration Screen
- 9.5 Transmit Queues Configuration Screen
- 9.6 Priority Classification Configuration Screen
- 9.7 Protocol Port Configuration Screen
- 9.8 Rate Limiting Configuration Screen
- Layer 3 Extensions Menu Screens
- Module Statistics Menu Screens
- Network Tools Screens
- VLAN Operation and Network Applications
- 13.1 Defining VLANs
- 13.2 Types of VLANs
- 13.3 Benefits and Restrictions
- 13.4 VLAN Terms
- 13.5 VLAN Operation
- 13.6 Configuration Process
- 13.7 VLAN Switch Operation
- 13.8 VLAN Configuration
- 13.9 Summary of VLAN Local Management
- 13.10 Quick VLAN Walkthrough
- 13.11 Examples
- 13.12 Example 1, Single Switch Operation
- 13.13 Example 2, VLANs Across Multiple Switches
- 13.14 Example 3, Filtering Traffic According to a Layer 4 Classification Rule
- 13.15 Example 4, Securing Sensitive Information According to Subnet
- 13.16 Example 5, Using Dynamic Egress to Control Traffic
- 13.17 Example 6, Locking a MAC Address to a Port Using Classification Rules
- Generic Attribute Registration Protocol (GARP)
- About IGMP
- Index

Detecting Multicast Routers
About IGMP B-3
B.3 DETECTING MULTICAST ROUTERS
The location of a router needs to be known in order to forward IGMP report frames back to the
router. The router(s) sends multicast routing protocol frames that get flooded throughout the
network. By snooping on these protocol, the switch will mark ports as connected to a router. The
port is put in a “forward all” mode where all multicast frames will be flooded. This allows all types
of IP multicast traffic (including IGMP streams) to go to the router.
There are many multicast routing protocols that the switch supports. These include the following:
• PIM version 1 and 2
• CBT (core based trees)
• MOSPF
• DVMRP
The routing protocols are detected as follows:
• All the multicast routing protocols have a destination address of 01-00-5E.
• DVMRP and PIM version 1 run over IGMP. If the IGMP frame type is not a REPORT, QUERY,
or LEAVE, then the frame is assumed to be one of these.
• PIM version 2 is IP protocol type 0x67.
• OSPF is IP protocol type 0x59. To detect that the frame is a multicast OSPF (MOSPF), the OSPF
data must be looked at. The data starts after the IP header. Byte 31 (options) needs to be checked.
If bit 2 is set (0x02 the MC bit), the frame is an MOSPF frame.
• CBT is IP protocol type 0x07.
• IGMP frames are detected by checking the IP protocol type. If the type is -x02, it is IGMP. The
first byte following the IP header is the IGMP frame type and version. (Note that the lower 4 bits
of the first byte in the IP header is the length of the IP header in 32-bit words) The version is
always 1, so the entire byte (version +type) may be used to check the IGMP type as follows:
0x11 = query
0x12 = report version 1
0x16 = report version 2
0x17 = leave