Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.112.0P1 - Page 365

Fast Convergence after MSTP Topology Changes When a port transitions to the Forwarding state as a result of an STP or MSTP topology change, Dell Networking OS sends a general query out of all ports except the multicast router ports. The host sends a response to the general query and the forwarding database is updated without having to wait for the query interval to expire. When an IGMP snooping switch is not acting as a querier, it sends out the general query in response to the MSTP triggered link-layer topology change, with the source IP address of 0.0.0.0 to avoid triggering querier election. Egress Interface Selection (EIS) for HTTP and IGMP Applications You can use the Egress Interface Selection (EIS) feature to isolate the management and front-end port domains for HTTP and IGMP traffic. Also, EIS enables you to configure the responses to switch-destined traffic by using the management port IP address as the source IP address. This information is sent out of the switch through the management port instead of the front-end port. The management EIS feature is applicable only for the out-of-band (OOB) management port. References in this section to the management default route or static route denote the routes configured using the management route command. The management default route can be either configured statically or returned dynamically by the DHCP client. A static route points to the management interface or a forwarding router. Transit traffic (destination IP not configured in the switch) that is received on the front-end port with destination on the management port is dropped and received in the management port with destination on the front-end port is dropped. Switch-destined traffic (destination IP configured in the switch) is: • Received in the front-end port with destination IP equal to management port IP address or management port subnet broadcast address is dropped. • Received in the management port with destination IP not equal to management IP address or management subnet broadcast address is dropped. Traffic (switch initiated management traffic or responses to switch-destined traffic with management port IP address as the source IP address) for user-specified management protocols must exit out of the management port. In this chapter, all the references to traffic indicate switch-initiated traffic and responses to switch-destined traffic with management port IP address as the source IP address. In customer deployment topologies, it might be required that the traffic for certain management applications needs to exit out of the management port only. You can use EIS to control and the traffic can exit out of any port based on the route lookup in the IP stack. One typical example is an SSH session to an unknown destination or an SSH connection that is destined to the management port IP address. The management default route can coexist with front-end default routes. If SSH is specified as a management application, SSH links to and from an unknown destination uses the management default route. Protocol Separation When you configure the application application-type command to configure a set of management applications with TCP/UDP port numbers to the OS, the following table describes the association between applications and their port numbers. Internet Group Management Protocol (IGMP) 365