Table of Contents
This document describes the features, caveats, and limitations for the Cisco Nexus 6000 Series devices and the Cisco Nexus 2000 Series Fabric Extenders. Use this document in combination with documents listed in the “Obtaining Documentation and Submitting a Service Request” section.
Note Release notes are sometimes updated with new information about restrictions and caveats. See the following website for the most recent version of the Cisco Nexus 6000 and Cisco Nexus 2000 Series release notes: http://www.cisco.com/en/US/docs/switches/datacenter/nexus6000/sw/release/notes/Nexus_6000_Release_Notes.html
Note Table 1 shows the online change history for this document.
The Cisco NX-OS software is a data center-class operating system built with modularity, resiliency, and serviceability at its foundation. Based on the industry-proven Cisco NX-OS software, Cisco NX-OS helps ensure continuous availability and sets the standard for mission-critical data center environments. The highly modular design of Cisco NX-OS makes zero-effect operations a reality and enables exceptional operational flexibility.
Several new hardware and software features are introduced for the Cisco Nexus 6000 Series device and the Cisco Nexus 2000 Series Fabric Extender (FEX) to improve the performance, scalability, and management of the product line.
The Cisco Nexus 6000 Series includes 10- and 40-Gigabit Ethernet density in energy-efficient compact form factor switches. The Cisco Nexus 6000 Series Layer 2 and Layer 3 set allow for multiple scenarios such as direct-attach 10- and 40-Gigabit Ethernet access and high-density Cisco Fabric Extender (FEX) aggregation deployments, leaf and spine architectures, or compact aggregation to build scalable Cisco Unified Fabric in the data centers.
Cisco Nexus 6000 Series products use the same set of Cisco application-specific integrated circuits (ASICs) and a single software image across the products within the family, which offers feature consistency and operational simplicity. Cisco Nexus 6000 Series switches support robust Layer 2 and Layer 3 functions, industry-leading FEX architecture with Cisco Nexus 2000 and Cisco Nexus B22 Blade FEX, in-service software upgrades (ISSUs), and Cisco FabricPath. Operational efficiency and programmability are enhanced on the Cisco Nexus 6000 Series through advanced analytics, PowerOn Auto Provisioning (POAP), and Python/Tool Command Language (Tcl) scripting.
The Cisco Nexus devices include a family of line-rate, low-latency, lossless 10-Gigabit Ethernet, Cisco Data Center Ethernet, Fibre Channel over Ethernet (FCoE), and native Fibre Channel devices for data center applications.
The Cisco Nexus 2000 Series Fabric Extender (FEX) is a highly scalable and flexible server networking solution that works with the Cisco Nexus 6000 Series devices to provide high-density and low-cost connectivity for server aggregation. Scaling across 1-Gigabit Ethernet, 10-Gigabit Ethernet, and 40-Gigabit Ethernet, unified fabric, rack, and blade server environments, the FEX is designed to simplify data center architecture and operations.
The FEX integrates with its parent Cisco Nexus device, which allows zero-touch provisioning and automatic configuration. The FEX provides a single point of management that supports a large numbers of servers and hosts that can be configured with the same feature set as the parent Cisco Nexus 6000 Series switch, including security and quality of service (QoS) configuration parameters. Spanning Tree Protocol (STP) is not required between the Fabric Extender and its parent switch, because the Fabric Extender and its parent switch allow you to enable a large multi-path, loop-free, active-active topology.
Software is not included with the Fabric Extender. Cisco NX-OS software is automatically downloaded and upgraded from its parent switch. For information about configuring the Cisco Nexus 2000 FEX, see the “Configuring the Fabric Extender” chapter in the Cisco Nexus 6000 Series Layer 2 Switching Configuration Guide .
Table 2 shows the hardware supported by Cisco NX-OS Release 7.x software.
Cisco Nexus 2248PQ FEX1
Table 3 shows the hardware and Cisco NX-OS Release 7.x software that supports online insertion and removal (OIR)
- New Software Features in Cisco NX-OS Release 7.0(4)N1(1)
- New Hardware Features in Cisco NX-OS Release 7.0(4)N1(1)
- New Software Features in Cisco NX-OS Release 7.0(3)N1(1)
- New Hardware Features in Cisco NX-OS Release 7.0(3)N1(1)
- New Software Features in Cisco NX-OS Release 7.0(2)N1(1)
- New Hardware Features in Cisco NX-OS Release 7.0(2)N1(1)
- New Software Features in Cisco NX-OS Release 7.0(1)N1(1)
- New Hardware Features in Cisco NX-OS Release 7.0(1)N1(1)
- New Software Features in Cisco NX-OS Release 7.0(0)N1(1)
- New Hardware Features in Cisco NX-OS Release 7.0(0)N1(1)
The FEX-based ACL Classification feature uses TCAM resources on a FEX to perform ACL-based packet classification of incoming packets on the switch. When QoS policies are processed on a FEX, the policies are enforced on the switch and on the associated FEX or FEXes.
Dynamic FCoE extends the capability and reliability of storage networks by leveraging FabricPath technology to create logical separation of SAN A and SAN B. FCoE VFCs and Interswitch-Links (ISLs) are dynamically configured, simplifying multihop FCoE deployments in leaf-spine topologies.
The Cisco TrustSec security architecture builds secure networks by establishing clouds of trusted network devices. Cisco TrustSec also uses the device information acquired during authentication for classifying, or coloring, the packets as they enter the network. This packet classification is maintained by tagging packets on ingress to the Cisco TrustSec network so that they can be properly identified for the purpose of applying security and other policy criteria along the data path.
- Anycast HSRP
- Data Analytics
- Dynamic Fabric Automation
- Early Warning for FIB Exhaustion
- ECN with WRED
- ERSPAN with ACL Filtering
- FabricPath Operations, Administration, and Management
- Intermediate System to Intermediate System Protocol
- Layer 2 Bidirectional Forwarding Detection
- Multi-Destination Switch Port Analyzer
- Multi-Destination Tree
- OpenFlow v1.0
- Overload Bit
- Port Channel Max Links
- Q-in-Q VLAN Tunneling
- Sampled NetFlow
- Switch Port Analyzer with ACL Filtering
- Static/Dynamic Network Address Translation
- TCAM Carving
Anycast HSRP is a FabricPath-based feature in which the traditional HSRP can be extended to an n-Gateway solution with all the gateways actively forwarding traffic. This feature supports active load balancing of traffic among all the gateways configured apart for redundancy. A maximum of 4 Gateways is supported.
This feature provides the capability of advanced analytics for network visibility and management. Critical analytics for network monitoring is supported including Latency Based SPAN, SPAN on Drop, Micro-Burst Monitor and Switch Latency.
This software release is the first release to support Cisco's Evolutionary Data Center Fabric solution called Dynamic Fabric Automation (DFA). DFA is evolutionary and is based on the industry leading Unified Fabric solution.
DFA focuses on simplifying, optimizing and automating data center fabric environments by offering an architecture based on four major pillars namely Fabric Management, Workload Automation, Optimized Networking and Virtual Fabrics. Each of these pillars provide a set of modular functions which can be used together or independently for easiness of adoption of new technologies in the data center environment.
Complete details on the DFA architecture can be found at: http://www.cisco.com/go/dfa.
Currently, the congestion control and avoidance algorithms for Transmission Control Protocol (TCP) are based on the idea that packet loss is an appropriate indication of congestion on networks transmitting data using the best-effort service model. When a network uses the best-effort service model, the network delivers data if it can, without any assurance of reliability, delay bounds, or throughput. However, these algorithms and the best-effort service model are not suited to applications that are sensitive to delay or packet loss (for instance, interactive traffic including Telnet, web-browsing, and transfer of audio and video data). Weighted Random Early Detection (WRED), and by extension, Explicit Congestion Notification (ECN), solves this problem.
With ERSPAN traffic the destination is remote and the overall impact of bandwidth congestion can be significant. The ERSPAN with ACL filtering feature allows you to filter ERSPAN traffic so that you can reduce bandwidth congestion. To configure ERSPAN with ACL filtering, you use ACL’s for the session to filter out traffic that you do not to span. An ACL is a list of permissions associated to any entity in the system; in the context of a monitoring session, an ACL is a list of rules which results in the spanning of traffic that matches the ACL criteria, saving bandwidth for more meaningful data. The filter would apply on all sources in the session (VLAN or interface).
Intermediate System to Intermediate System (IS-IS) is an Interior Gateway Protocol (IGP) based on Standardization (ISO)/International Engineering Consortium (IEC) 10589. Cisco Nexus devices support Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6). IS-IS is a dynamic link-state routing protocol that can detect changes in the network topology and calculate loop-free routes to other nodes in the network. Each router maintains a link-state database that describes the state of the network and sends packets on every configured link to discover neighbors. IS-IS floods the link-state information across the network to each neighbor. The router also sends advertisements and updates on the link-state database through all the existing neighbors.
The Bidirectional Forwarding Detection (BFD) provides fast forwarding-path failure detection times for media types, encapsulations, topologies, and routing protocols. You can use BFD to detect forwarding path failures at a uniform rate, rather than at variable rates for different protocol hello mechanisms. BFD makes network profiling and planning easier and reconvergence time consistent and predictable.
Local Switch Port Analyzer (SPAN) and SPAN-on-Drop sessions can support multiple destination ports. This allows traffic in a single local SPAN session or a SPAN-on-Drop session also to be monitored and sent to multiple destinations.
A Multi-Destination Tree (MDT), also referred to as a forwarding tag or ftag, is a spanning-tree used for forwarding packets within a topology. A topology has two MDTs/ ftags: topology 0 has ftag 1 and 2, topology 1 has ftag 3 and 4.
The OpenFlow feature is a specification from the Open Networking Foundation (ONF) that defines a flow-based forwarding infrastructure (L2-L4 Ethernet switch model) and a standardized application programmatic interface (protocol definition) to learn capabilities, add and remove flow control entries and request statistics. OpenFlow allows a controller to direct the forwarding functions of a switch through a secure channel.
Support has been added for One Platform Kit (onePK) Turbo API. OnePK is a cross-platform API and software development kit that enables you to develop applications that interact directly with Cisco networking devices. onePK provides you access to networking services by using a set of controlled APIs that share the same programming model and style. For more information, see the following URL:
Intermediate System to Intermediate System (IS-IS) uses the overload bit to tell other routers not to use the local router to forward traffic but to continue routing traffic destined for that local router.
A Q-in-Q VLAN tunnel enables a service provider to segregate the traffic of different customers in their infrastructure, while still giving the customer a full range of VLANs for their internal use by adding a second 802.1Q tag to an already tagged frame.
The Sampled NetFlow feature samples incoming packets on an interface. The packets sampled then qualify to create flows. Sampled NetFlow reduces the amount of export data sent to the collector by limiting the number of packets that create flows and the number of flows. It is essential when flows are created on a line card or external device, instead of on the forwarding engine.
The Switch Port Analyzer (SPAN) with Access Control List (ACL) filtering feature allows you to filter SPAN traffic so that you can reduce bandwidth congestion. To configure SPAN with ACL filtering, you use ACL’s for the session to filter out traffic that you do not want to span. An ACL is a list of permissions associated to any entity in the system; in the context of a monitoring session, an ACL is a list of rules which results in spanning only the traffic that matches the ACL criteria, saving bandwidth for more meaningful data. The filter can apply to all sources in the session.
Network Address Translation (NAT) enables private IP internetworks that use nonregistered IP addresses to connect to the Internet. NAT operates on a device, usually connecting two networks, and translates private (not globally unique) IP addresses in the internal network into legal IP addresses before packets are forwarded to another network. You can configure NAT to advertise only one IP address for the entire network to the outside world. This ability provides additional security, effectively hiding the entire internal network behind one IP address.
The VN-Segment feature defines a new way to "tag" packets on the wire replacing the traditional 802.1Q VLAN tag. This feature uses a 24-bit tag also referred to as a Virtual Network Identifier (VNI). CE links (access and trunk) carry traditional VLAN tagged/untagged frames. These are the VN-Segment Edge ports.
WCCPv2 specifies interactions between one or more Cisco NX-OS routers and one or more cache engines. WCCPv2 transparently redirects selected types of traffic through a group of routers. The selected traffic is redirected to a group of cache engines to optimize resource usage and lower response times.
Table 4 shows the upgrade and downgrade possibilities for Cisco NX-OS Release 7.0(3)N1(1). For more information, see the Cisco Nexus 6000 Series NX-OS Software Upgrade and Downgrade Guide, Release 7.0.
Nondisruptive upgrade 2
- The Server Virtualization Switch (SVS) connection is not deleted during a rollback when NIV is enabled. To resolve this issue, delete the current SVS connection and reapply the original SVS connection. For details, see CSCts17033.
- If you configure a Cisco Nexus 2248TP port to 100 Mbps instead of autonegotiation, then autonegotiation does not occur, which is the expected behavior. Both sides of the link should be configured to both hardwired speed or both autonegotiate.
- When a private VLAN port is configured as a TX (egress) SPAN source, the traffic seen at the SPAN destination port is marked with the VLAN of the ingressed frame. There is no workaround.
- In large-scale configurations, some Cisco Nexus 2000 Series Fabric Extenders might take up to 3 minutes to appear online after entering the reload command. A configuration can be termed large scale when the maximum permissible Cisco Nexus 2000 Series Fabric Extenders are connected to a Cisco Nexus 6000 Series switch, all host-facing ports are connected, and each host-facing interface has a large configuration that supports the maximum permissible ACEs per interface.
- The Cisco Nexus 2148 Fabric Extender does not support frames with the dot1q vlan 0 tag.
- VACLs of more than one type on a single VLAN are unsupported. Cisco NX-OS software supports only a single type of VACL (either MAC, IPv4, or IPv6) applied on a VLAN. When a VACL is applied to a VLAN, it replaces the existing VACL if the new VACL is a different type. For instance, if a MAC VACL is configured on a VLAN and then an IPv6 VACL is configured on the same VLAN, the IPv6 VACL is applied, and the MAC VACL is removed.
- A MAC ACL is applied only on non-IP packets. Even if there is a match eth type = ipv4 statement in the MAC ACL, it does not match an IP packet. To avoid this situation, use IP ACLs to apply access control to the IP traffic instead of using a MAC ACL that matches the EtherType to IPv4 or IPv6.
- Multiple boot kickstart statements in the configuration are not supported.
- If you configure Multiple Spanning Tree (MST) on a Cisco Nexus 6000 Series switch, avoid partitioning the network into a large number of regions.
- By design, vEth interfaces do not share the underlying behavior of a vPC port. As a result, a VLAN is not suspended when the peer switch suspends it. For example, when you shut a VLAN on a primary switch, the VLAN continues to be up on the secondary switch when the vEth interface is on a FEX. When the VLAN on the primary switch goes down, the VLAN on the vEth interface on the primary is suspended, but the vEth on the secondary switch remains up because it is an active VLAN on the secondary switch.
- The packet length in the IP GRE header of a packet exiting from the switch is not equal to the MTU value configured in the ERSPAN source session. This is true for SPAN or ERSPAN. The Cisco Nexus 6000 Series switch terminates in multiples of 16 bytes. If MTU is configured as 100 bytes, then the actual truncated packet is 96 bytes.
- Unknown unicast packets in FabricPath ports are counted as multicast packets in interface counters. This issue occurs when unknown Unicast packets are sent and received with a reserved multicast address (that floods to a VLAN) in the outer FabricPath header, and the Cisco Nexus 6000 Series switch increments the interface counter based on the outer FabricPath header. As a result, Multicast counters are incremented. There is no workaround for this issue.
- In an emulated switch setup, an inband keepalive does not work. The following steps are recommended for peer keepalive over SVI when a switch is in FabricPath mode:
- The limit of the table that holds the Router MAC and Virtual MAC entries for determining packet routing or switching is 500 entries. The Virtual MAC entries, the MAC used for HSRP/VRRP that is also programmed in this table, can be shared across multiple Layer 3 interfaces. If SVIs 1–100 all have the same group number configured, just one entry needs to be programmed in this table. We recommend that you configure the same group ID across all or multiple Layer 3 interfaces/SVIs. If multiple group IDs are configured on an Layer 3 interface, we recommend that you configure the same set of group IDs across all or multiple Layer 3 interfaces. This configuration supports HSRP/VRRP on more interfaces.
- The maximum IP MTU that can be set on Layer 3 interfaces running Layer 3 protocols is 9192 because of the internal header used inside the switch. The related network-qos policy must be set to 9216.
- On a Cisco Nexus device, if the SPAN source is a FEX port, the frames will always be tagged when leaving the SPAN destination.
- On a Cisco Nexus 6000 Series switch, if the SPAN source is an access port on a switch port or FEX port, the spanned frames at the SPAN destination will be tagged.
- On a Cisco Nexus 6000 Series switch, if the SPAN source is on an access port on the switch port, the frames will not be tagged when leaving the SPAN destination.
- Ports on a FEX can be configured as a tx-source in one session only.
If two ports on the same FEX are enabled to be tx-source, the ports need to be in the same session. If you configure a FEX port as a tx-source and another port belonging to the same FEX is already configured as a tx-source on a different SPAN session, an error is displayed on the CLI.
- When a FEX port is configured as a tx-source, the multicast traffic is spanned on all VLANs that the tx-source port is a member of. The FEX port sends out only multicast packets that are not filtered by IGMP snooping. For example, if FEX ports 100/1/1–12 are configured on VLAN 11 and the switch port 1/5 sends multicast traffic on VLAN 11 in a multicast group, and hosts connected to FEX ports 100/1/3–12 are interested in receiving that multicast traffic (through IGMP), then that multicast traffic goes out on FEX ports 100/1/3–12, but not on 100/1/1–2.
If you configure SPAN Tx on port 100/1/1, although the multicast traffic does not egress out of port 100/1/1, the SPAN destination does receive that multicast traffic, which is due to a design limitation.
- When a FEX port is configured as both SPAN rx-source and tx-source, broadcast non-IGMP Layer-2 multicast frames as well as unknown unicast frames originating from that port might be seen twice on the SPAN destination: once on the ingress and once on the egress path. On the egress path, the frames are filtered by the FEX to prevent them from going out on the same port on which they were received. For example, if FEX port 100/1/1 is configured on VLAN 11 and is also configured as SPAN rx-source and tx-source and a broadcast frame is received on that port, the SPAN destination recognizes two copies of the frame, even though the frame is not sent back on port 100/1/1.
- A FEX port cannot be configured as a SPAN destination. Only a switch port can be configured and used as a SPAN destination.
- With a SPAN on Latency session, FEX ports cannot be configured as source or destination.
In a vPC topology, two Cisco Nexus 6000 Series switches configured as vPC peer switches need to be configured symmetrically for Layer 3 configurations such as SVIs, a peer gateway, routing protocol and policies, and RACLs.
- Open Caveats
- Resolved Caveats in Cisco NX-OS Release 7.0(4)N1(1)
- Resolved Caveats in Cisco NX-OS Release 7.0(3)N1(1)
- Resolved Caveats in Cisco NX-OS Release 7.0(2)N1(1)
- Resolved Caveats in Cisco NX-OS Release 7.0(1)N1(1)
- Resolved Caveats in Cisco NX-OS Release 7.0(0)N1(1)
Table 5 lists descriptions of open caveats in Cisco NX-OS Release 7.0(2)N1(1)
The Cisco Management Information Base (MIB) list includes Cisco proprietary MIBs and many other Internet Engineering Task Force (IETF) standard MIBs. These standard MIBs are defined in Requests for Comments (RFCs). To find specific MIB information, you must examine the Cisco proprietary MIB structure and related IETF-standard MIBs supported by the Cisco Nexus 6000 Series switch.
For information on obtaining documentation, using the Cisco Bug Search Tool (BST), submitting a service request, and gathering additional information, see What’s New in Cisco Product Documentation at: http://www.cisco.com/c/en/us/td/docs/general/whatsnew/whatsnew.html .
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