Users Guide

● 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 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 field 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 142. 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 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 traffic from
the South or lower-end of the vertically-aligned network.
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Virtual Link Trunking (VLT)