Ethernet Switching
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Contributor
JulioCassettez
Posts: 77
Registered: ‎12-08-2010
0

Operational Duplex Resolution

This seems like a dumb question, but is it me, or is it difficult to determine whether the EX switch has actually negotiated to full duplex when connected to legacy 10/100m devices?

 

It's 2012, so I'm assuming when connected to 1g devices, interfaces are running at full duplex.

 

But we still have some older 10/100 devices out there.  A previous post got me thinking about troubleshooting such devices.

 

How come a "show interface x extensive" is so vague regarding the operational state of the duplex?

 

Here's from a switchport connected to a Cisco router that only does 10/100 and is set to auto.  Where does the EX say something like "I'm set to auto, but based on the advertised characteristics of the neighbor, I'm actually running at 100-full"?

 

dude@ex3200-1# run show interfaces ge-0/0/19 extensive 
Physical interface: ge-0/0/19, Enabled, Physical link is Up
  Interface index: 149, SNMP ifIndex: 512, Generation: 152
  Link-level type: Ethernet, MTU: 1514, Speed: Auto, Duplex: Auto, BPDU Error: None, MAC-REWRITE Error: None,
  Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled,
  Remote fault: Online
  Device flags   : Present Running
  Interface flags: SNMP-Traps Internal: 0x0
  Link flags     : None
  CoS queues     : 8 supported, 8 maximum usable queues
  Hold-times     : Up 0 ms, Down 0 ms
  Current address: b0:c6:9a:69:d7:93, Hardware address: b0:c6:9a:69:d7:93
  Last flapped   : 2012-02-24 02:21:15 UTC (2w2d 13:49 ago)
  Statistics last cleared: Never
  Traffic statistics:
   Input  bytes  :           9781395486                 1072 bps
   Output bytes  :           1583949372                  512 bps
   Input  packets:              8177242                    1 pps
   Output packets:              6109773                    1 pps
   IPv6 transit statistics:
    Input  bytes  :                   0 
    Output bytes  :                   0
    Input  packets:                   0
    Output packets:                   0
  Input errors:
    Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Policed discards: 0, L3 incompletes: 0, L2 channel errors: 0,
    L2 mismatch timeouts: 0, FIFO errors: 0, Resource errors: 0
  Output errors:
    Carrier transitions: 3, Errors: 0, Drops: 0, Collisions: 0, Aged packets: 0, FIFO errors: 0, HS link CRC errors: 0,
    MTU errors: 0, Resource errors: 0
  Egress queues: 8 supported, 4 in use
  Queue counters:       Queued packets  Transmitted packets      Dropped packets
    0 best-effort                    0              5441462                 5559
    1 assured-forw                   0                    0                    0
    5 expedited-fo                   0                    0                    0
    7 network-cont                   0               668312                    0
  Queue number:         Mapped forwarding classes
    0                   best-effort 
    1                   assured-forwarding
    5                   expedited-forwarding
    7                   network-control 
  Active alarms  : None
  Active defects : None
  MAC statistics:                      Receive         Transmit
    Total octets                    9781395486       1583949372
    Total packets                      8177242          6109773
    Unicast packets                    7794195          5006374
    Broadcast packets                       95           290759
    Multicast packets                   382952           812640
    CRC/Align errors                         0                0
    FIFO errors                              0                0
    MAC control frames                       0                0
    MAC pause frames                         0                0
    Oversized frames                         0
    Jabber frames                            0
    Fragment frames                          0
    Code violations                          0
  Autonegotiation information:
    Negotiation status: Complete
    Link partner:
        Link mode: Full-duplex, Flow control: None, Remote fault: OK, Link partner Speed: 100 Mbps
    Local resolution:
        Flow control: Symmetric, Remote fault: Link OK
  Packet Forwarding Engine configuration:
    Destination slot: 0
  CoS information:
    Direction : Output 
    CoS transmit queue               Bandwidth               Buffer Priority   Limit
                              %            bps     %           usec
    0 best-effort            95       95000000    95             NA      low    none
    7 network-control         5        5000000     5             NA      low    none
  Interface transmit statistics: Disabled

  Logical interface ge-0/0/19.0 (Index 88) (SNMP ifIndex 536) (Generation 153)
    Flags: SNMP-Traps Encapsulation: ENET2
    Bandwidth: 0
    Traffic statistics:
     Input  bytes  :             47508867
     Output bytes  :             77061469
     Input  packets:               364685
     Output packets:               672908
    Local statistics:
     Input  bytes  :             47508867
     Output bytes  :             77061469
     Input  packets:               364685
     Output packets:               672908
    Transit statistics:
     Input  bytes  :                    0                    0 bps
     Output bytes  :                    0                    0 bps
     Input  packets:                    0                    0 pps
     Output packets:                    0                    0 pps
    Protocol eth-switch, Generation: 167, Route table: 0
      Flags: None

[edit]
dude@ex3200-1# 

 

 

Cisco's implementation is virtually dummy proof:

 

sw-3560#show int status

Port      Name               Status       Vlan       Duplex  Speed Type
Fa0/1                        notconnect   1            auto   auto 10/100BaseTX
Fa0/2                        notconnect   1            auto   auto 10/100BaseTX
Fa0/3                        connected    trunk      a-full  a-100 10/100BaseTX
Fa0/4                        connected    trunk      a-full  a-100 10/100BaseTX
Fa0/5                        connected    1          a-full  a-100 10/100BaseTX
Fa0/6                        notconnect   1            auto   auto 10/100BaseTX
Fa0/7                        notconnect   routed       auto   auto 10/100BaseTX
Fa0/8                        notconnect   1            auto   auto 10/100BaseTX
Gi0/1                        notconnect   1            auto   auto Not Present
Po1                          notconnect   1            auto   auto 

 

Contributor
jackycheung
Posts: 52
Registered: ‎02-02-2010
0

Re: Operational Duplex Resolution

Juniper seems can't see what exactly running wen you configured with auto:

 

  Link-level type: Ethernet, MTU: 1514, Speed: Auto, Duplex: Auto, BPDU Error: None, MAC-REWRITE Error: None,
  Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled,

 

You may need to hardcore the link speed and duplex if you want to see so.....

JNCIP-SP/ENT/SEC
Super Contributor
motd
Posts: 221
Registered: ‎12-16-2008
0

Re: Operational Duplex Resolution

This bit shows the autoneg results:


  Autonegotiation information:
    Negotiation status: Complete
    Link partner:
        Link mode: Full-duplex, Flow control: None, Remote fault: OK, Link partner Speed: 100 Mbps
    Local resolution:
        Flow control: Symmetric, Remote fault: Link OK


This is the output of "show interface X media".  If autoneg fails (or is disabled in config), the status will be "Incomplete".

In this case the link is operating at 100Mbps Full-duplex.

 

Contributor
JulioCassettez
Posts: 77
Registered: ‎12-08-2010
0

Re: Operational Duplex Resolution

Maybe the indentations are misleading me.  To me, it looks like the output is describing 3 separate things:

 

1.  Negotiation Status:

2.  Link partner:

3.  Local resolution:

 

I have 3 examples (also described in the descriptions of the interfaces).  First one should see that the other end doesn't support autonegotiation and fallback to 10/half.  Second one should autonegotiate to 100/full.  Third one should autonegotiate to 1000/full.

 

The only one that seems to be clear is when autonegotiation isn't supported (is "incomplete").  Only then does it clearly state "local link speed: 10 Mbps, Link mode: Half-duplex".  All others just say "Negotiation status:  Complete" and goes on to say what the neighbor is capable of.  Are we to assume that "complete" always means the duplex resolved to full?

 

Is anybody else surprised by the lack of clear, consise display of the *resulting* negotiation status of the speed/duplex on a Juniper switch?  Of all the things to be unclear about on an ethernet switch!

 

root@ex3200-1# run show interfaces ge-0/0/18 media                          
Physical interface: ge-0/0/18, Enabled, Physical link is Up
  Interface index: 148, SNMP ifIndex: 511
  Description: Old Cisco 2511 that doesn't support auto negotiation - goes to 10/half
  Link-level type: Ethernet, MTU: 1514, Speed: Auto, Duplex: Auto,
  BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled,
  Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled,
  Remote fault: Online
  Device flags   : Present Running
  Interface flags: SNMP-Traps Internal: 0x0
  Link flags     : None
  CoS queues     : 8 supported, 8 maximum usable queues
  Current address: b0:c6:9a:69:d7:92, Hardware address: b0:c6:9a:69:d7:92
  Last flapped   : 2012-02-26 20:25:24 UTC (2w3d 19:43 ago)
  Input rate     : 6720 bps (12 pps)
  Output rate    : 5112 bps (9 pps)
  Active alarms  : None
  Active defects : None
  MAC statistics:
    Input bytes: 26159527, Input packets: 267578, Output bytes: 362013605,
    Output packets: 1951007
  Autonegotiation information:
    Negotiation status: Incomplete
    Local resolution:                   
        Local link Speed: 10 Mbps, Link mode: Half-duplex
  Interface transmit statistics: Disabled

[edit]
root@ex3200-1# run show interfaces ge-0/0/19 media    
Physical interface: ge-0/0/19, Enabled, Physical link is Up
  Interface index: 149, SNMP ifIndex: 512
  Description: Cisco 1841 that supports 10/100 and left to autonegotiate
  Link-level type: Ethernet, MTU: 1514, Speed: Auto, Duplex: Auto,
  BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled,
  Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled,
  Remote fault: Online
  Device flags   : Present Running
  Interface flags: SNMP-Traps Internal: 0x0
  Link flags     : None
  CoS queues     : 8 supported, 8 maximum usable queues
  Current address: b0:c6:9a:69:d7:93, Hardware address: b0:c6:9a:69:d7:93
  Last flapped   : 2012-02-24 02:21:15 UTC (2w6d 13:47 ago)
  Input rate     : 3040 bps (4 pps)
  Output rate    : 7048 bps (8 pps)
  Active alarms  : None
  Active defects : None
  MAC statistics:
    Input bytes: 12310006470, Input packets: 10482434, Output bytes: 1818743012,
    Output packets: 8859350
  Autonegotiation information:
    Negotiation status: Complete
    Link partner:
        Link mode: Full-duplex, Flow control: None, Remote fault: OK,
        Link partner Speed: 100 Mbps
    Local resolution:
        Flow control: Symmetric, Remote fault: Link OK
  Interface transmit statistics: Disabled

[edit]
root@ex3200-1# run show interfaces ge-0/0/9 media     
Physical interface: ge-0/0/9, Enabled, Physical link is Up
  Interface index: 139, SNMP ifIndex: 520
  Description: Modern 10/100/1000 Laptop
  Link-level type: Ethernet, MTU: 1514, Speed: Auto, Duplex: Auto,
  BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled,
  Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled,
  Remote fault: Online
  Device flags   : Present Running
  Interface flags: SNMP-Traps Internal: 0x0
  Link flags     : None
  CoS queues     : 8 supported, 8 maximum usable queues
  Current address: b0:c6:9a:69:d7:89, Hardware address: b0:c6:9a:69:d7:89
  Last flapped   : 2012-03-15 13:53:29 UTC (02:15:43 ago)
  Input rate     : 0 bps (0 pps)
  Output rate    : 1016 bps (1 pps)
  Active alarms  : None
  Active defects : None
  MAC statistics:
    Input bytes: 3180669573, Input packets: 4310798, Output bytes: 2829825265,
    Output packets: 3440813
  Autonegotiation information:
    Negotiation status: Complete
    Link partner:
        Link mode: Full-duplex, Flow control: None, Remote fault: OK,
        Link partner Speed: 1000 Mbps
    Local resolution:
        Flow control: Symmetric, Remote fault: Link OK
  Interface transmit statistics: Disabled

 

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