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
