Fabric Extender (FEX)
- EoR + ToR
- Nexus 2k
- no local switching
- cannot be connected to switch (hardcoded BPDU guard), only end host on L2
- VN-tag between FEX and parent:
- IEEE 802.1BR
- VIF: virtual interface
- edge ports
- static pinning: if uplink fails, all downlinks mapped to it → down
(config)# install feature-set fex
(config)# feature-set fex
; ID – unique across VDCs
(config)# fex <ID>
(config-fex)# type <TYPE>
; 1 default ≡ all hosts via single link, static pinning
(config-fex)# pinning max-links <N>
; enable FCoE
(config-fex)# fcoe
(config)# interface port-channel <N>
(config-if)# switchport mode fex-fabric
; dynamic pinning, max-links = 1 ≡ all traffic via port-channel
(config-if)# fex-associate <ID>
# show fex
# show interface port-channel <N> fex-intf
VN-tag
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EtherType |d|p| Destination VIF |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L|R|Ver| Source VIF |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
d: direction
- 0 ≡ host-to-network
- 1 ≡ network-to-host
p: pointer, 1 ≡ mcast frame, egress replication
L: looped, 1 ≡ frame is sent back to source N2k
R: reserved
Destination VIF: 0 ≡ from N2k, undefined
Source VIF:
- set by N2k
- set by master (copied), if received from N2k