Administrator Guide
RRoCE packets are received and transmitted on specic interfaces called lite-subinterfaces. These interfaces are similar to the normal
Layer 3 physical interfaces except for the extra provisioning that they oer to enable the VLAN ID for encapsulation.
You can congure a physical interface or a Layer 3 Port Channel interface as a lite subinterface. When you congure a lite subinterface, only
tagged IP packets with VLAN encapsulation are processed and routed. All other data packets are discarded.
To provide lossless service for RRoCE, the QoS service policy must be congured in the ingress and egress directions on lite subinterfaces.
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.
When a storage area network (SAN) is connected over an IP network, the following conditions must be satised:
• 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 undened 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 trac-handling
operations.
RRoCE has IP headers. RRoCE is bursty and uses the entire 10-Gigabit Ethernet interface. Although RRoCE and normal data trac are
propagated in separate network portions, it may be necessary in certain topologies to combine both the RRoCE and the data trac in a
single network structure. RRoCE trac 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 trac. For normal IP or data
trac 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.
Flex Hash and Optimized Boot-Up
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