Users Guide
NA messages can be sent in two scenarios:
• 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 eld set to the unicast MAC address of the initial NS sender. This solicited NA must be tunneled when they reach the wrong
peer.
• Sometimes NA messages are sent by a node when its link-layer address changes. This NA message is sent as an unsolicited NA to
advertise its new address and the destination address eld is set to the link-local scope of all-nodes multicast address. This unsolicited
NA packet does not have to be tunneled.
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 is tunneled to Unit 2 along with some control information. The control information present in the tunneled NA packet
is processed in such a way so 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 127. Sample
Conguration of IPv6 Peer Routing in a VLT Domain
Sample Conguration of IPv6 Peer Routing in a VLT Domain
Consider a sample scenario as shown in the following gure 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 the ToR and the VLT nodes is Layer 2. Servers or
hosts that are connected to the ToR (Node B) generate Layer 3 control/data trac from the South or lower-end of the vertically-aligned
network.
Virtual Link Trunking (VLT)
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