Users Guide

• When a Virtual Machine (VM) moves from one VLT domain to the another VLT domain, the VM host sends the gratuitous ARP
(GARP) , which in-turn triggers a mac movement from the previous VLT domain to the newer VLT domain.
• After a station move, if the host sends a TTL1 packet destined to its gateway; for example, a previous VLT node, the packet can be
dropped.
• After a station move, if the host first PINGs its gateway; for example, a previous VLT node it results in a 40 to 60% success rate
considering it takes a longer path.
• When you remove and add back a MAC address, L3 frames can be received out-of-order at the L3 cloud. This happens when proxy
gateway routing and sub-optimal routing intersperse with each other.
Enabling the VLT Proxy Gateway
To enable the VLT proxy gateway, the system mac addresses of C and D in the local VLT domain must be installed in C1 and D1 in the
remote VLT domain and vice versa. You can install the mac address in two methods - the proxy-gateway lldp method or the
proxy-gateway static configuration. Proxy-gateway LLDP is a dynamic method of installing the local mac addresses in the remote
VLT domain, which is achieved using a new organizational type, length, value (TLV) in LLDP packets.
You can configure the VLT proxy gateway in a VLT domain using the proxy-gateway LLDP command in proxy-gateway Configuration
mode. Specify the port-channel interface of the square VLT link on which LLDP packets are sent using thepeer-domain-link port-
channel command.
Configuring the proxy gateway lldp and the peer-domain-link port channel, LLDP sets TLV flags on the interfaces for
receiving and transmitting private TLV packets. After defining these organizational TLV settings, LLDP encodes the local system mac-
addresses as organizational TLVs for transmitting to the peer. If you specify the no proxy gateway LLDP interface command,
LLDP stops transmitting and receiving proxy gateway TLV packets on the specified interfaces. However, other TLVs are not affected.
From the interfaces on which you enabled the proxy gateway LLDP, LLDP decodes the TLV packets from the remote LLDP by using the
new organizational TLV.
The following requirements must be satisfied for LLDP proxy gateway to function correctly:
• Data centers must be directly connected.
• LLDP has a limited TLV size. As a result, information that is carried by the new TLV is limited to one or two MAC addresses.
• You must have all related systems properly configured and set up.
LLDP Organizational TLV for Proxy Gateway
• LLDP defines an organizationally specific TLV (type 127) with a unique identifier (0x0001E8) and a defined subtype (0x01) for sending
or receiving information.
• LLDP uses the existing infrastructure and adds a new TLV for sending and receiving on the configured ports.
• There are only a few MAC addresses for each unit transmitted. All currently active MAC addresses are carried on the newly defined
TLV.
• Dell Networking devices not configured with VLT proxy gateway process standard TLVs and ignore TLVs configured with VLT proxy
gateway.
The LLDP organizational TLV passes local destination MAC address information to peer VLT domain devices so they can act as a proxy
gateway. To enable proxy gateway LLDP, two configurations are required:
• You must configure the global proxy gateway LLDP to enable the proxy-gateway LLDP TLV.
• You must configure the interface proxy gateway LLDP to enable or disable a proxy-gateway LLDP TLV on specific interfaces.
• The interface is typically a VLT port-channel that connects to a remote VLT domain.
• The new proxy gateway TLV is carried on the physical links under the port channel only.
• You must have at least one link connection to each unit of the VLT domain.
Following are the prerequisites for Proxy Gateway LLDP configuration:
• You must globally enable LLDP.
• You cannot have interface–level LLDP disable commands on the interfaces configured for proxy gateway and you must enable both
transmission and reception.
• You must connect both units of the remote VLT domain by the port channel member.
• If you connect more than one port to a unit of the remote VLT domain, the connection must be completed by the time you enable the
proxy gateway LLDP.
• You cannot have other conflicting configurations (for example, you cannot have a static proxy gateway configuration).
Proxy Gateway LLDP configuration might not operate properly if one of the following conditions is true:
VLT Proxy Gateway
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