sh ip arp
This will help map the IPs to MACs, very helpful in vPC environments.
sh mac address table
This will help map the IPs to MACs, very helpful in vPC environments.
sh mac address table
Friday, October 9, 2015
Thursday, October 8, 2015
VNTag- 802.1br and Instantiation of Virtual Interfaces
VN-Tag
VN-Tag refers to the format of the information tag inserted into each frame exchanged between the Cisco fabric extenders and the Nexus parent switch. It helps create a virtual link/path between different vif (virtual interfaces) residing within the single host and tied to single/multiple VMs.
Basically, it used by the NIV adapter to tag egressing packets which will be passed on to the FI through the FEX (VNTag is transparent to FEX).
For a non-NIV adapter, the switch applies the VNTag to egressing packets.
Virtual Interfaces (VIFs) are used for virtualized Ethernet (Veths) and FC (Vfc) interfaces.
They can also help us identify the origin server to which these vifs belong to.
On SP association, the VIFs are created on the FI (samdb) and correspond to frame-level tags assigned to blade/rack physical adapters.
A 6-byte tag(VN-Tag) is inserted into the frame at egress on the server port by the adapter firmware and helps identify the interface. Every VIF (Veth or Vfc) will have a VN-Tag associated with it.
Each EthX/Y/Z interface (northbound ports) of a blade/rack server will have one or more VIFs associated with it.
Destination Bit [1-bit] – Indicates which direction the frame is flowing.
Pointer bit [1-bit] – indicated that a vif_list_id is included in the tag.
Destination VIF – [14-bits] – Identifies the destination port.
Looped – Identifies the source vNIC, ment to identify multicast frames to ensure it is not forwarded back to where it originated.
Reserved [2-bits] – For future use.
Source VIF [12-bits] – vif_id of the downstream port.
Version [2-bits] – Set to 0
VNTag-802.1br - IEEE
VN-Tag refers to the format of the information tag inserted into each frame exchanged between the Cisco fabric extenders and the Nexus parent switch. It helps create a virtual link/path between different vif (virtual interfaces) residing within the single host and tied to single/multiple VMs.
Basically, it used by the NIV adapter to tag egressing packets which will be passed on to the FI through the FEX (VNTag is transparent to FEX).
For a non-NIV adapter, the switch applies the VNTag to egressing packets.
In short, VNTAG/VN-Link is MAC-in-MAC encapsulation to enable virtualization of network traffic
VIFs
They can also help us identify the origin server to which these vifs belong to.
On SP association, the VIFs are created on the FI (samdb) and correspond to frame-level tags assigned to blade/rack physical adapters.
A 6-byte tag(VN-Tag) is inserted into the frame at egress on the server port by the adapter firmware and helps identify the interface. Every VIF (Veth or Vfc) will have a VN-Tag associated with it.
Each EthX/Y/Z interface (northbound ports) of a blade/rack server will have one or more VIFs associated with it.
VN-TAG FORMAT
EtherType [16-bits] = 0x8926Destination Bit [1-bit] – Indicates which direction the frame is flowing.
Pointer bit [1-bit] – indicated that a vif_list_id is included in the tag.
Destination VIF – [14-bits] – Identifies the destination port.
Looped – Identifies the source vNIC, ment to identify multicast frames to ensure it is not forwarded back to where it originated.
Reserved [2-bits] – For future use.
Source VIF [12-bits] – vif_id of the downstream port.
Version [2-bits] – Set to 0
VNTag-802.1br - IEEE
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