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Tunneling of IPv6 ND in a VLT Domain
Tunneling an NA packet from one VLT node to its peer is required because an NA may reach the wrong VLT node instead of arriving
at the destined VLT node. This may occur because of LAG hashing at the top of the rack (ToR) switch. The tunneled NA will carry
some control information along with it so that the appropriate VLT node can mimic the ingress port as the VLT interface rather than
pointing to VLT node’s interconnecting link (ICL link).
The overall tunneling process involves the VLT nodes that are connected from TOR through a LAG. The picture below is a basic VLT
setup, which describes the communication between VLT nodes to tunnel the NA from one VLT node to its peer.
NA messages can be sent in two types of scenarios:
•
Sometimes NA messages are sent by a node when its link-layer address is changed. This NA message is sent as an unsolicited
NA to advertise its new address and the destination address field is set to the link-local scope of all-nodes multicast address. This
unsolicited NA packet need not be tunneled.
•
NA messages are almost always sent in response to an NS message from a node. In this case the solicited NA has the
destination address field set to the unicast MAC address of the initial NS sender. This solicited NA need to be tunneled when
they reach the wrong peer.
Consider a sample scenario in which two VLT nodes, Unit1 and Unit2, are connected in a VLT domain using an ICL or VLTi link. To the
south of the VLT domain, Unit1 and Unit2 are connected to a ToR switch named Node B. Also, Unit1 is connected to another node,
Node A, and Unit2 is linked to a node, Node C. When an NS traverses from Unit2 to Node B(TOR) and a corresponding NA reaches
Unit1 because of LAG hashing , this NA must be tunneled to Unit 2 along with some control information. The control information
present in the tunneled NA packet is processed in such a way that the ingress port is marked as the link from Node B to Unit 2
rather than pointing to ICL link through which tunneled NA arrived.
Figure 144. Sample Configuration of IPv6 Peer Routing in a VLT Domain
Sample Configuration of IPv6 Peer Routing in a VLT Domain
Consider a sample scenario as shown in the following figure in which two VLT nodes, Unit1 and Unit2, are connected in a VLT domain
using an ICL or VLTi link. To the south of the VLT domain, UNit1 and Unit2 are connected to a ToR switch named Node B. Also, Unit1
is connected to another node, Node A, and Unit2 is linked to a node, Node C. The network between TOR to VLT Nodes is purely L2
in nature. Servers or hosts that are connected to the ToR (Node B) generate the L3 control/data traffic from the South or lower-end
of the vertically-aligned network.
Virtual Link Trunking (VLT)
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Summary of Contents for S4048-ON
Page 1: ...Dell Configuration Guide for the S4048 ON System 9 9 0 0 ...
Page 146: ...Figure 14 BFD Three Way Handshake State Changes 146 Bidirectional Forwarding Detection BFD ...
Page 522: ...Figure 87 Configuring Interfaces for MSDP 522 Multicast Source Discovery Protocol MSDP ...
Page 523: ...Figure 88 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 523 ...
Page 528: ...Figure 91 MSDP Default Peer Scenario 1 528 Multicast Source Discovery Protocol MSDP ...
Page 529: ...Figure 92 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 529 ...
Page 530: ...Figure 93 MSDP Default Peer Scenario 3 530 Multicast Source Discovery Protocol MSDP ...
Page 633: ...Policy based Routing PBR 633 ...
Page 777: ...Figure 119 Single and Double Tag TPID Match Service Provider Bridging 777 ...
Page 778: ...Figure 120 Single and Double Tag First byte TPID Match 778 Service Provider Bridging ...