Dell S4048T-ON, Configuration Manual

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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 configuration. For more information, see the
Dell Networking OS Command Line Reference Guide .
Topics:
• Proxy Gateway in VLT Domains
• Configuring a Static VLT Proxy Gateway
• Configuring an LLDP VLT Proxy Gateway
• VLT Proxy Gateway Sample Topology
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 benefits:
• 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 figure 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.
For more information about eVLT, refer to the Virtual Link Trunking (VLT) chapter. 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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