User manual SMC 8126L2

[. . . ] MANAGEMENT GUIDE ta SMC8126L2 SMC8150L2 TigerSwitchTM 10/100/1000 26-Port Gigabit Managed Switch 50-Port Gigabit Managed Switch TigerSwitch 10/100/1000 Management Guide From SMC's Tiger line of feature-rich workgroup LAN solutions 20 Mason Irvine, CA 92618 Phone: (949) 679-8000 September 2007 Pub. # 149100036100A E092007-AP-R01 Information furnished by SMC Networks, Inc. However, no responsibility is assumed by SMC for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of SMC. [. . . ] Additional considerations when the switch itself is a DHCP client ­ The port(s) through which the switch submits a client request to the DHCP server must be configured as trusted. Note that the switch will not add a dynamic entry for itself to the binding table when it receives an ACK message from a DHCP server. Also, when the switch sends out DHCP client packets for itself, no filtering takes place. However, when the switch receives any messages from a DHCP server, any packets received from untrusted ports are dropped. DHCP Snooping Configuration Command Attributes · DHCP Snooping Status ­ Enables or disables DHCP snooping globally. · DHCP Snooping MAC-Address Verification ­ Enables or disables MAC address verification. DHCP packets will be dropped if the source MAC address in the Ethernet header of the packet is not same as the client's hardware address in the DHCP packet. Web ­ Click DHCP Snooping, Configuration. Figure 3-114 DHCP Snooping Configuration CLI ­ This example first enables DHCP Snooping, and then enables DHCP Snooping MAC-Address Verification. Console(config)#ip dhcp snooping Console(config)#ip dhcp snooping verify mac-address Console(config)# 4-231 4-235 3-187 3 Configuring the Switch DHCP Snooping VLAN Configuration Enables DHCP snooping on the specified VLAN. (Range: 1-4094) · DHCP Snooping Status ­ Enables or disables DHCP snooping for the selected VLAN. When DHCP snooping is enabled globally on the switch, and enabled on the specified VLAN, DHCP packet filtering will be performed on any untrusted ports within the VLAN. Web ­ Click DHCP Snooping, VLAN Configuration. Figure 3-115 DHCP Snooping VLAN Configuration CLI ­ This example first enables DHCP Snooping for VLAN 1. Console(config)#ip dhcp snooping vlan 1 Console(config)# 4-233 DHCP Snooping Information Option Configuration DHCP provides a relay mechanism for sending information about the switch and its DHCP clients to the DHCP server. Known as DHCP Option 82, it allows compatible DHCP servers to use the information when assigning IP addresses, or to set other services or policies for clients. When the DHCP Snooping Information Option is enabled, clients can be identified by the switch port to which they are connected rather than just their MAC address. DHCP client-server exchange messages are then forwarded directly between the server and client without having to flood them to the entire VLAN. In some cases, the switch may receive DHCP packets from a client that already includes DHCP Option 82 information. The switch can be configured to set the action policy for these packets. Either the switch can discard the DHCP information, keep the existing information, or replace it with the switch's relay information. Note: DHCP snooping must be enabled on the switch for the DHCP Option 82 information to be inserted into packets. 3-188 DHCP Snooping Command Attributes 3 · DHCP Snooping Information Option Status ­ Enables or disables DHCP Option 82 information relay. · DHCP Snooping Information Option Policy ­ Sets the DHCP snooping information option policy for DHCP client packets that include Option 82 information. · Replace ­ Overwrites the DHCP client packet information with the switch's relay information. · Drop ­ Discards the Option 82 information in a packet and then floods it to the entire VLAN. Web ­ Click DHCP Snooping, Information Option Configuration. Figure 3-116 DHCP Snooping Information Option Configuration CLI ­ This example enables DHCP Snooping Information Option, and sets the policy as replace. Console(config)#ip dhcp snooping information option Console(config)#ip dhcp snooping information policy replace Console(config)# 4-235 4-236 DHCP Snooping Port Configuration Configures switch ports as trusted or untrusted. An untrusted interface is an interface that is configured to receive messages from outside the network or firewall. [. . . ] It allows switches to assign endstations to different virtual LANs, and defines a standard way for VLANs to communicate across switched networks. IEEE 802. 1p An IEEE standard for providing quality of service (QoS) in Ethernet networks. The standard uses packet tags that define up to eight traffic classes and allows switches to transmit packets based on the tagged priority value. IEEE 802. 1X Port Authentication controls access to the switch ports by requiring users to first enter a user ID and password for authentication. IEEE 802. 3ac Defines frame extensions for VLAN tagging. IEEE 802. 3x Defines Ethernet frame start/stop requests and timers used for flow control on full-duplex links. (Now incorporated in IEEE 802. 3-2002) Glossary-2 Glossary IGMP Snooping Listening to IGMP Query and IGMP Report packets transferred between IP Multicast Routers and IP Multicast host groups to identify IP Multicast group members. IGMP Query On each subnetwork, one IGMP-capable device will act as the querier -- that is, the device that asks all hosts to report on the IP multicast groups they wish to join or to which they already belong. The elected querier will be the device with the lowest IP address in the subnetwork. Internet Group Management Protocol (IGMP) A protocol through which hosts can register with their local router for multicast services. [. . . ]