Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 1070

* In one possible topology, a switch uses the BMP feature to receive its IP address, configuration files, and boot image from a DHCP server that connects to the switch through the VLT domain. In the port-channel used by the switch to connect to the VLT domain, configure the port interfaces on each VLT peer as hybrid ports before adding them to the port channel (refer to Connecting a VLT Domain to an Attached Access Device (Switch or Server)). To configure a port in Hybrid mode so that it can carry untagged, single-tagged, and double-tagged traffic, use the portmode hybrid command in Interface Configuration mode as described in Configuring Native VLANs. * For example, if the DHCP server is on the ToR and VLTi (ICL) is down (due to either an unavailable peer or a link failure), whether you configured the VLT LAG as static or LACP, when a single VLT peer is rebooted in BMP mode, it cannot reach the DHCP server, resulting in BMP failure. • Software features supported on VLT port-channels - In a VLT domain, the following software features are supported on VLT port-channels: 802.1p, ingress and egress ACLs, BGP, DHCP relay, IS-IS, OSPF, active-active PIM-SM, PIM-SSM, VRRP, Layer 3 VLANs, LLDP, flow control, port monitoring, jumbo frames, IGMP snooping, sFlow, ingress and egress ACLs, and Layer 2 control protocols RSTP only). NOTE: PVST+ passthrough is supported in a VLT domain. PVST+ BPDUs does not result in an interface shutdown. PVST+ BPDUs for a nondefault VLAN is flooded out as any other L2 multicast packet. On a default VLAN, RTSP is part of the PVST+ topology in that specific VLAN (default VLAN). - For detailed information about how to use VRRP in a VLT domain, see the following VLT and VRRP interoperability section. - For information about configuring IGMP Snooping in a VLT domain, see VLT and IGMP Snooping. - All system management protocols are supported on VLT ports, including SNMP, RMON, AAA, ACL, DNS, FTP, SSH, Syslog, NTP, RADIUS, SCP, TACACS+, Telnet, and LLDP. - Enable Layer 3 VLAN connectivity VLT peers by configuring a VLAN network interface for the same VLAN on both switches. - Dell Networking does not recommend enabling peer-routing if the CAM is full. To enable peer- routing, a minimum of two local DA spaces for wild card functionality are required. • Software features supported on VLT physical ports - In a VLT domain, the following software features are supported on VLT physical ports: 802.1p, LLDP, IPv6 dynamic routing, flow control, port monitoring, and jumbo frames. - In a VLT domain, ingress and egress QoS policies are supported on physical VLT ports, which can be members of VLT port channels in the domain. * Ingress and egress QoS policies applied on VLT ports must be the same on both VLT peers. * You should apply the same ingress and egress QoS policies on VLTi (ICL) member ports to handle failed links. • Software features not supported with VLT - In a VLT domain, the following software features are not supported on non-VLT ports: 802.1x, DHCP snooping, and FRRP. • VLT and VRRP interoperability - In a VLT domain, VRRP interoperates with virtual link trunks that carry traffic to and from access devices (see Overview). The VLT peers belong to the same VRRP group and are assigned master and backup roles. Each peer actively forwards L3 traffic, reducing the traffic flow over the VLT interconnect. - VRRP elects the router with the highest priority as the master in the VRRP group. To ensure VRRP operation in a VLT domain, configure VRRP group priority on each VLT peer so that a peer is either the master or backup for all VRRP groups configured on its interfaces. For more information, see Setting VRRP Group (Virtual Router) Priority. 1070 Virtual Link Trunking (VLT)