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Virtual Link Trunking (VLT)
Virtual link trunking (VLT) allows physical links between two chassis to appear as a single virtual link to the network core or other
switches such as Edge, Access, or top-of-rack (ToR).
Overview
VLT reduces the role of spanning tree protocols (STPs) by allowing link aggregation group (LAG) terminations on two separate
distribution or core switches and supporting a loop-free topology.
To prevent the initial loop that may occur prior to VLT being established, use a spanning tree protocol. After VLT is established, you
may use rapid spanning tree protocol (RSTP) to prevent loops from forming with new links that are incorrectly connected and
outside the VLT domain.
VLT provides Layer 2 multipathing, creating redundancy through increased bandwidth, enabling multiple parallel paths between
nodes and load-balancing traffic where alternative paths exist.
Virtual link trunking offers the following benefits:
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Allows a single device to use a LAG across two upstream devices.
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Eliminates STP-blocked ports.
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Provides a loop-free topology.
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Uses all available uplink bandwidth.
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Provides fast convergence if either the link or a device fails.
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Optimized forwarding with virtual router redundancy protocol (VRRP).
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Provides link-level resiliency.
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Assures high availability.
CAUTION: Dell Networking does not recommend enabling Stacking and VLT simultaneously. If you enable both features
at the same time, unexpected behavior occurs.
As shown in the following example, VLT presents a single logical Layer 2 domain from the perspective of attached devices that have
a virtual link trunk terminating on separate chassis in the VLT domain. However, the two VLT chassis are independent Layer2/Layer3
(L2/L3) switches for devices in the upstream network. L2/L3 control plane protocols and system management features function
normally in VLT mode. Features such as VRRP and internet group management protocol (IGMP) snooping require state information
coordinating between the two VLT chassis. IGMP and VLT configurations must be identical on both sides of the trunk to ensure the
same behavior on both sides.
The following example shows how VLT is deployed. The switches appear as a single virtual switch from the point of view of the
switch or server supporting link aggregation control protocol (LACP).
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Virtual Link Trunking (VLT)
Содержание S4048-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 9 0 0 ...
Страница 146: ...Figure 14 BFD Three Way Handshake State Changes 146 Bidirectional Forwarding Detection BFD ...
Страница 477: ...Figure 68 Inspecting Configuration of LAG 10 on ALPHA Link Aggregation Control Protocol LACP 477 ...
Страница 480: ...Figure 70 Inspecting a LAG Port on BRAVO Using the show interface Command 480 Link Aggregation Control Protocol LACP ...
Страница 481: ...Figure 71 Inspecting LAG 10 Using the show interfaces port channel Command Link Aggregation Control Protocol LACP 481 ...
Страница 522: ...Figure 87 Configuring Interfaces for MSDP 522 Multicast Source Discovery Protocol MSDP ...
Страница 523: ...Figure 88 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 523 ...
Страница 524: ...Figure 89 Configuring PIM in Multiple Routing Domains 524 Multicast Source Discovery Protocol MSDP ...
Страница 528: ...Figure 91 MSDP Default Peer Scenario 1 528 Multicast Source Discovery Protocol MSDP ...
Страница 529: ...Figure 92 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 529 ...
Страница 530: ...Figure 93 MSDP Default Peer Scenario 3 530 Multicast Source Discovery Protocol MSDP ...
Страница 633: ...Policy based Routing PBR 633 ...
Страница 777: ...Figure 119 Single and Double Tag TPID Match Service Provider Bridging 777 ...
Страница 778: ...Figure 120 Single and Double Tag First byte TPID Match 778 Service Provider Bridging ...