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Cisco Nexus 1000V Troubleshooting Guide, Release 5.2(1)SV3(1.1)
OL-31593-01
Chapter 25 VXLANs
Information About VXLANs
Import RT chg/chg-pending : 0/0
A few additional commands are as follows:
•
show bgp event-history msgs
•
show bgp event-history events
Multi-MAC Capability
You can use multi-MAC addresses to mark a virtual Ethernet interface as capable of sourcing packets
from multiple MAC addresses. For example, you can use this feature if you have a virtual Ethernet port
and you have enabled VXLAN trunking on it and the VM that is connected to the port bridges packets
that are sourced from multiple MAC addresses.
By using this feature, you can easily identify multi-MAC capable ports and handle live migration
scenarios correctly for those ports.
Fragmentation
The VXLAN encapsulation overhead is 50 bytes. To prevent performance degradation due to
fragmentation, the entire interconnection infrastructure between all VEMs exchange VXLAN packets
must be configured to carry 50 bytes more than what the VM VNICs are configured to send. For
example, if the default VNIC configuration is 1500 bytes, you must configure the VEM uplink port
profile, upstream physical switch port, interswitch links, and any routers to carry a maximum
transmission unit (MTU) of at least 1550 bytes. If that is not possible, we recommend that the MTU
within the guest VMs you configure to be smaller by 50 bytes.
If you do not configure a smaller MTU, the VEM attempts to notify the VM if it performs Path MTU
(PMTU) Discovery. If the VM does not send packets with a smaller MTU, the VM fragments the IP
packets. Fragmentation occurs only at the IP layer. If the VM sends a frame that is too large, the frame
is to be dropped after VXLAN encapsulation and if the frame does not contain an IP packet.
Scalability
Maximum Number of VXLANs
The Cisco Nexus 1000V supports a total of 4000 and 6144 bridge domains.
VSM-DAOX(config-port-prof-srv)#
show resource-availability vlan
Maximum number of user VLANs supported: 4093
Number of user VLANs created : 3968
Total number of available user VLANs : 125
Note: Total number of available user VLANs additionally depend on number of
bridge-domains under usage. Please verify the usage of bridge-domains too.
VSM-DAOX(config-port-prof-srv)#
show resource-availability bridge-domain
Maximum number of bridge-domains per DVS: 6144
Number of bridge-domains currently created: 5004
Number of bridge-domains available*: 1140
* available bridge-domains do not account for created VLANs