Service Manual

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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
Virtual Link Trunking (VLT)
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