Reference Guide
2. Use the load-balance flexhash command to specify whether IPv4 or IPv6 packets must be subjected to the flex hash
functionality, a unique protocol number, the offset of hash fields from the start of the L4 header to be used for hash
calculation, and a meaningful description to associate the protocol number with the name.
CONFIGURATION mode
Dell(conf)# load-balance flexhash ipv4/ipv6 ip-proto <protocol number> <description
string> offset1 <offset1 value> [offset2 <offset2 value>]
To delete the configured flex hash setting, use the no version of the command.
RDMA Over Converged Ethernet (RoCE) Overview
This functionality is supported on the Z9500 platform.
RDMA is a technology that a virtual machine (VM) uses to directly transfer information to the memory of another VM, thus
enabling VMs to be connected to storage networks. With RoCE, RDMA enables data to be forwarded without passing through
the CPU and the main memory path of TCP/IP. In a deployment that contains both the RoCE network and the normal IP
network on two different networks, RRoCE combines the RoCE and the IP networks and sends the RoCE frames over the IP
network. This method of transmission, called RRoCE, results in the encapsulation of RoCE packets to IP packets. RRoCE sends
Infini Band (IB) packets over IP. IB supports input and output connectivity for the internet infrastructure. Infini Band enables the
expansion of network topologies over large geographical boundaries and the creation of next-generation I/O interconnect
standards in servers.
When a storage area network (SAN) is connected over an IP network, the following conditions must be satisfied:
● Faster Connectivity: QoS for RRoCE enables faster and lossless nature of disk input and output services.
● Lossless connectivity: VMs require the connectivity to the storage network to be lossless always. When a planned upgrade
of the network nodes happens, especially with top-of-rack (ToR) nodes where there is a single point of failure for the VMs,
disk I/O operations are expected to occur in 20 seconds. If disk in not accessible in 20 seconds, unexpected and undefined
behavior of the VMs occurs. You can optimize the booting time of the ToR nodes that experience a single point of failure to
reduce the outage in traffic-handling operations.
RRoCE is bursty and uses the entire 10-Gigabit Ethernet interface. Although RRoCE and normal data traffic are propagated in
separate network portions, it may be necessary in certain topologies to combine both the RRoCE and the data traffic in a single
network structure. RRoCE traffic is marked with dot1p priorities 3 and 4 (code points 011 and 100, respectively) and these
queues are strict and lossless. DSCP code points are not tagged for RRoCE. Both ECN and PFC are enabled for RRoCE traffic.
For normal IP or data traffic that is not RRoCE-enabled, the packets comprise TCP and UDP packets and they can be marked
with DSCP code points. Multicast is not supported in that network.
RRoCE packets are received and transmitted on specific interfaces called lite-subinterfaces. These interfaces are similar to the
normal Layer 3 physical interfaces except for the extra provisioning that they offer to enable the VLAN ID for encapsulation.
You can configure a physical interface or a Layer 3 Port Channel interface as a lite subinterface. When you configure a lite
subinterface, only tagged IP packets with VLAN encapsulation are processed and routed. All other data packets are discarded.
A normal Layer 3 physical interface processes only untagged packets and makes routing decisions based on the default Layer 3
VLAN ID (4095).
To enable routing of RRoCE packets, the VLAN ID is mapped to the default VLAN ID of 4095 using VLAN translation. After the
VLAN translation, the RRoCE packets are processed in the same way as normal IP packets that a Layer 3 interface receives and
routes in the egress direction. At the egress interface, the VLAN ID is appended to the packet and transmitted out of the
interface as a tagged packet with the dot1Q value preserved.
To provide lossless service for RRoCE, the QoS service policy must be configured in the ingress and egress directions on lite sub
interfaces.
Preserving 802.1Q VLAN Tag Value for Lite
Subinterfaces
This functionality is supported on the platform.
All the frames in a Layer 2 VLAN are identified using a tag defined in the IEEE 802.1Q standard to determine the VLAN to which
the frames or traffic are relevant or associated. Such frames are encapsulated with the 802.1Q tags. If a single VLAN is
configured in a network topology, all the traffic packets contain the same do1q tag, which is the tag value of the 802.1Q header.
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Flex Hash