Users Guide

VLT Proxy Gateway

The virtual link trucking (VLT) proxy gateway feature allows a VLT domain to locally terminate and route L3 packets that are destined to a

Layer 3 (L3) end point in another VLT domain. Enable the VLT proxy gateway using the link layer discover protocol (LLDP) method or the

static conguration. For more information, see the Dell Networking OS Command Line Reference Guide.

Topics:

• Proxy Gateway in VLT Domains

• Conguring a Static VLT Proxy Gateway

• Conguring an LLDP VLT Proxy Gateway

Proxy Gateway in VLT Domains

Using a proxy gateway, the VLT peers in a domain can route the L3 packets destined for VLT peers in another domain as long as they have

L3 reachability for the IP destinations.

A proxy gateway in a VLT domain provides the following benets:

• Avoids sub-optimal routing of packets by a VLT domain when packets are destined to the endpoint in another VLT domain.

• Provides resiliency if a VLT peer goes down by performing proxy routing for the peer’s destination MAC address in another VLT domain.

A typical scenario is virtual movement of servers across data centers. Virtual movement enables live migration of running virtual machines

(VMs) from one host to another without downtime. For example, consider a square VLT connecting two data centers. If a VM, VM1 on

Server Rack 1 has C as its default gateway and VM1 performs a virtual movement to Server Rack 2 with no change in default gateway. In

this case, L3 packets destined for C can be routed either by C1 or D1 locally. To do this, install the local system mac address of C and D in

both C1 and D1 so the packets for C and D could have a hit at C1 /D1 and be routed locally.

The following gure shows:

• Server racks, named Rack 1 and Rack 2, are part of data centers named DC1 and DC2, respectively.

• Rack 1 is connected to devices A and B in Layer 2.

• Rack 2 is connected to devices A and B in Layer 2.

• A VLT link aggregation group (LAG) is present between A and B.

• A and B are connected to core routers, C and D.

• VLT routing is present between C and D.

• C1 and D1 are Layer 3 core routers in DC2, in which VLT routing is enabled.

• The core routers C and D in the local VLT domain is connected to the core routers C1 and D1 in the remote VLT Domain using VLT links

in eVLT fashion.

The core or Layer 3 routers C and D in local VLT Domain and C1 and D1 in the remote VLT Domain are then part of a Layer 3 cloud.

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