Cisco Cisco Nexus 5010 Switch デザインガイド
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The Cisco Nexus 5000 Series performs a Layer 2 MAC address table lookup based on the destination MAC
address of the frame, and it performs learning based on the source VIF and populates the destination VIF in case
the destination is attached to a fabric extender (a different fabric extender or the same one).
The traffic sent to a fabric extender (N2H) includes a VN-Tag, with the destination VIF information populated to
indicate the port on the fabric extender for which the traffic is destined, and with the “d” bit set to 1 to indicate the
indicate the port on the fabric extender for which the traffic is destined, and with the “d” bit set to 1 to indicate the
N2H direction.
In case the traffic is multicast, the VN-
Tag is configured with the “p” bit set to 1 to indicate that the content of the
destination VIF is not a destination port, but a pointer to a list of ports.
In the case of multicast traffic on the fabric extender, the replication occurs on the fabric extender itself for the ports
connected to the fabric extender, and not on the Cisco Nexus 5000 Series Switch.
Different multicast groups with fanouts (outgoing interface lists) that differ only based on fabric extender ports will
appear within a Cisco Nexus 5000 Series Switch as if they had the same fanout. In other words, what matters to
the Cisco Nexus 5000 Series in terms of fanout is the fabric interface to which the traffic goes, and not the HIF to
which it goes.
If a Cisco Nexus 5000 Series Switch sends a packet out the same physical port through which the packet entered
(for example, if the source and destination interfaces reside on the same physical interface), the Cisco Nexus 5000
Series Switch sets the L bit (loop bit) in the VN-Tag packet and copies the source VIF of the original packet in its
VN-Tag packet to the fabric extender. This process allows the source VIF interface to recognize its packet and
drop it.
Note that when the L bit is not set, the VN-Tag packet from the Cisco Nexus 5000 Series Switch carries zero in the
source VIF of the VN-Tag.
Given that the multicast indexes are based on the destinations that need to receive the frame (VLAN flood or
multicast group), when the source is part of the group, the looped check prevents the frame from returning to the
sender.
Topology Choices for Connecting Cisco Nexus 5000 and 2000 Series
A fabric extender can connect to the Cisco Nexus 5000 Series Switch with a single-homed topology, often referred
to as a straight-through connection without vPC, shown in Figure 32. With the single-homed topology, each fabric
extender is attached to a single Cisco Nexus 5000 Series Switch.
As of Cisco NX-OS 5.1(3)N1(1) up to 24 fabric extenders can be attached to a single Cisco Nexus 5500 platform
switch, for a total of up to 1152 host ports for each Cisco Nexus 5500 platform switch.
As of Cisco NX-OS 5.1(3)N1(1) up to 12 fabric extenders can be attached to a single Cisco Nexus 5020 or 5010
Switch, for a total of up to 576 host ports for each Cisco Nexus 5020 or 5010 Switch.
In a typical deployment, you would use two Cisco Nexus 5000 Series Switches for redundancy, and servers would
connect redundantly to a fabric extender that depends on n5k01 and another fabric extender that depends on
n5k02.
NIC teaming options supported in this topology are:
●
Active-standby mode
●
Active-active transmit load-balancing mode