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Cisco Bug: CSCvh81489 - Cosmetic:N9K with Copper Port 'show interface capabilities' reports MDIX no, but it is enabled

Last Modified

Aug 13, 2019

Products (1)

  • Cisco Nexus 9000 Series Switches

Known Affected Releases

7.0(3)I2(4)

Description (partial)

Symptom:
Cosmetic: on N9K copper ports, MDIX is enabled by default.  However the 'show interface capabilities' command reports incorrectly MDIX:   no. 

When performing a physical loopback between 2 routed ports, we can see that the copper link comes up and that MDIX is enabled.


Physical loopback:  1/4 (copper) <---STRAIGHT-THROUGH cable ----> 1/5 (copper) 

9K# show int e1/4 capabilities | in MDIX
  MDIX:                  no   <<----------------------------  incorrect

9K# show int e1/5 capabilities | in MDIX
  MDIX:                  no    <<---------------------------- incorrect

sh cdp ne int e1/4
Capability Codes: R - Router, T - Trans-Bridge, B - Source-Route-Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater,
                  V - VoIP-Phone, D - Remotely-Managed-Device,
                  s - Supports-STP-Dispute

Device-ID          Local Intrfce  Hldtme Capability  Platform      Port ID
9K(SAL19079J8T)     Eth1/4         143    R S s     N9K-C93120TX  Eth1/5

9K# sh system internal ethpm info interface e1/4 | egrep -i  "mdix|^Admin|^Operational \("
Admin Config Information:
  auto neg(on), auto mdix(on), beacon(off), num_of_si(0)
Operational (Runtime) Information:
  mdix mode(mdix), primary vlan(1), cfg_acc_vlan(1)    <<--------- mdix mode(mdix)


9K# sh system internal ethpm info interface e1/5 | egrep -i  "mdix|^Admin|^Operational \("
Admin Config Information:
  auto neg(on), auto mdix(on), beacon(off), num_of_si(0)
Operational (Runtime) Information:
  mdix mode(mdix), primary vlan(1), cfg_acc_vlan(1)    <<--------- mdix mode(mdix)

T2 platform:

9K# bcm-shell module 1 "port xe3"
PORT: Status (* indicates PHY link up)
  xe3     LS(SW) Auto(no link) Ability (fd = 100MB,1000MB,10GB hd =  intf = xgmii medium = copper pause = pause_tx,pause_rx,pause_asymm lb = none,MAC,PHY flags = autoneg )Local (fd = 100MB,1000MB,10GB hd =  intf = medium =  pause =  lb =  flags =  )Stad(84:b8:02:78:fe:0b) STP(Block) Lrn(ARL,FWD) UtPri(0) Pfm(FloodNone) IF(XGMII) PH(Auto) Max_frame(1582) MDIX(Auto, Xover) Medium(Copper) Fault(LocalRemote) VLANFILTER(3)  <<--------  MDIX kicked in (Auto,Xover)

9K# bcm-shell module 1 "port xe4"
PORT: Status (* indicates PHY link up)
 *xe4     LS(SW) Auto(10GFD) Ability (fd = 100MB,1000MB,10GB hd =  intf = xgmii medium = copper pause = pause_tx,pause_rx,pause_asymm lb = none,MAC,PHY flags = autoneg )Local (fd = 100MB,1000MB,10GB hd =  intf = medium =  pause =  lb =  flags =  )Remote (fd = 100MB,1000MB,10GB hd =  intf =  medium =  pause =  lb =  flags =  )Stad(84:b8:02:78:fe:0c) STP(Block) Lrn(ARL,FWD) UtPri(0) Pfm(FloodNone) IF(XGMII) PH(Auto) Max_frame(1582) MDIX(Auto, Normal) Medium(Copper) VLANFILTER(3)

Conditions:
Physical loopback between 2 copper ports: e.g. 1/4 <-------> 1/5  using a straight-through cable

9K# sh run int e1/4-5

!Command: show running-config interface Ethernet1/4-5
!Time: Mon Jan 29 23:34:47 2018

version 7.0(3)I2(4)

interface Ethernet1/4
  description straight-through
  no switchport
  vrf member TAC
  no shutdown

interface Ethernet1/5
  description straight-through
  no switchport
  no shutdown
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