Dell Force10 S4820T S4820T Configuration Guide - Page 1010

www.dell.com | support.dell.com • If the DHCP server is located on the ToR and the VLTi (ICL) is down due to a failed link when a VLT node is rebooted in JumpStart mode, it will not be able to reach the DHCP server, resulting in BMP failure. Configuration Notes When you configure VLT, the following conditions apply: • VLT domain • A VLT domain supports two chassis members, which appear as a single logical device to network access devices connected to VLT ports through a port channel. • A VLT domain consists of the two core chassis, the interconnect trunk, backup link, and the LAG members connected to attached devices. • Each VLT domain has a a unique MAC address that is created automatically by VLT or user-configured. • ARP tables are synchronized between the VLT peer nodes. • VLT peer switches operate as separate chassis with independent control and data planes for devices attached on non-VLT ports. • One chassis in the VLT domain is assigned a primary role; the other chassis takes the secondary role. The primary and secondary roles are required for scenarios when connectivity between the chassis is lost. VLT assigns the primary chassis role according to the lowest MAC address. The primary role is also user-configurable. • In a VLT domain, the peer switches must run the same FTOS software version • You must separately configure each VLT peer switch with the same VLT domain ID and the VLT version. If the system detects mismatches between VLT peer switches in the VLT domain ID or VLT version, the VLT Interconnect (VLTi) will not activate. To find the reason for the VLTi being down, use the show vlt statistics command to verify there are mismatch errors, then use the show vlt brief command on each VLT peer to view the VLT version on the peer switch. If the VLT version is more than one release different from the current version in use, the VLTi will not activate. • The chassis members in a VLT domain support connection to orphan hosts and switches that are not connected to both switches in the VLT core. • VLT interconnect (VLTi) • The VLT interconnect must consist of either 10G or 40G ports. A maximum of eight 10G or four 40G ports is supported. A combination of 10G and 40G ports is not supported. • A VLT interconnect over 1G ports is not supported. • The port channel must be in default mode (not switchport) to be recognized by VLTi. • The system will automatically include required VLANs in VLTi. You do not need to manually select VLANs. • VLT peer switches operate as separate chassis with independent control and data planes for devices attached on non-VLT ports. • Port-channel link aggregation (LAG) across the ports in the VLT interconnect is required; individual ports are not supported. Dell Force10 strongly recommends configuring a static LAG for VLTi. • The VLT interconnect synchronizes L2 and L3 control-plane information across the two chassis. 1010 | Virtual Link Trunking (VLT)