Basic About-face Anchorage Configuration
The three key agreement elements on a Cisco about-face anchorage are auto-negotiation, speed, and
duplex. Cisco switches use auto-negotiation by default; it is again disabled if both the acceleration and
duplex are manually configured. You can set the acceleration application the acceleration {auto | 10 | 100 | 1000}
interface subcommand, bold the interface supports assorted speeds. You configure the duplex
setting application the bifold {auto | bisected | full} interface subcommand.
Example 1-1 shows the chiral agreement of the acceleration and bifold on the articulation amid Switch1
and Switch4 from Figure 1-3, and the after-effects of accepting altered bifold settings. (The book
refers to specific about-face commands acclimated on IOS-based switches, referred to as “Catalyst IOS” by
the Cisco CCIE blueprint.)
Figure 1-3 Simple Switched Network with Trunk
Example 1-1 Chiral Ambience for Bifold and Speed, with Altered Duplex
switch1# appearance interface fa 0/13
FastEthernet0/13 is up, band agreement is up
Hardware is Fast Ethernet, abode is 000a.b7dc.b78d (bia 000a.b7dc.b78d)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s
! actual curve bare for brevity
! Below, Switch1’s interface abutting to Switch4 is configured for 100 Mbps,
! HDX. Note that IOS rejects the aboriginal bifold command; you cannot set bifold until
! the acceleration is manually configured.
switch1# conf t
Enter agreement commands, one per line. End with CNTL/Z.
switch1(config)# int fa 0/13
switch1(config-if)# bifold half
Duplex will not be set until acceleration is set to non-auto value
switch1(config-if)# acceleration 100
Ethernet Layer 1: Wiring, Speed, and Bifold 13
05:08:41: %LINEPROTO-5-UPDOWN: Band agreement on Interface FastEthernet0/13, afflicted state
to down
05:08:46: %LINEPROTO-5-UPDOWN: Band agreement on Interface FastEthernet0/13, afflicted state
to up
switch1(config-if)# bifold half
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! NOT SHOWN: Agreement for 100/half on Switch4’s int fa 0/13.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! Now with both switches manually configured for acceleration and duplex, neither will be
! application Ethernet auto-negotiation. As a result, beneath the bifold ambience on Switch1
! can be afflicted to FDX with Switch4 actual configured to use HDX.
switch1# conf t
Enter agreement commands, one per line. End with CNTL/Z.
switch1(config)# int fa 0/13
switch1(config-if)# bifold full
05:13:03: %LINEPROTO-5-UPDOWN: Band agreement on Interface FastEthernet0/13, afflicted state
to down
05:13:08: %LINEPROTO-5-UPDOWN: Band agreement on Interface FastEthernet0/13, afflicted state
to up
switch1(config-if)#^Z
switch1# sh int fa 0/13
FastEthernet0/13 is up, band agreement is up
! Curve bare for brevity
Full-duplex, 100Mb/s
! actual curve bare for brevity
! Below, Switch4 is apparent to be HDX. Note
! the collisions counters at the end of the appearance interface command.
switch4# sh int fa 0/13
FastEthernet0/13 is up, band agreement is up (connected)
Hardware is Fast Ethernet, abode is 000f.2343.87cd (bia 000f.2343.87cd)
MTU 1500 bytes, BW 100000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 100Mb/s
! Curve bare for brevity
5 minute achievement amount 583000 bits/sec, 117 packets/sec
25654 packets input, 19935915 bytes, 0 no buffer
Received 173 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
0 ascribe errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 173 multicast, 0 abeyance input
0 ascribe packets with distill action detected
26151 packets output, 19608901 bytes, 0 underruns
54 achievement errors, 5 collisions, 0 interface resets
0 babbles, 54 backward collision, 59 deferred
0 absent carrier, 0 no carrier, 0 PAUSE output
0 achievement absorber failures, 0 achievement buffers swapped out
continues
Example 1-1 Chiral Ambience for Bifold and Speed, with Altered Bifold (Continued)
Example 1-1 Chiral Ambience for Bifold and Speed, with Altered Bifold (Continued)
02:40:49: %CDP-4-DUPLEX_MISMATCH: bifold conflict apparent on FastEthernet0/13
(not abounding duplex), with Switch1 FastEthernet0/13 (full duplex).
! Above, CDP letters accept been exchanged over the articulation amid switches. CDP
! exchanges advice about Bifold on the link, and can apprehension (but not fix)
! the mismatch.
The statistics on switch4 abreast the end of the archetype appearance collisions (detected in the time during
which the aboriginal 64 bytes were actuality transmitted) and backward collisions (after the aboriginal 64 bytes were
transmitted). In an Ethernet that follows cabling breadth restrictions, collisions should be detected
while the aboriginal 64 bytes are actuality transmitted. In this case, Switch1 is application FDX logic, meaning
it sends frames anytime—including back Switch4 is sending frames. As a result, Switch4 receives
frames anytime, and if sending at the time, it believes a blow has occurred. Switch4 has
deferred 59 frames, acceptation that it chose to delay afore sending frames because it was currently
receiving a frame. Also, the retransmission of the frames that Switch4 anticipation were destroyed due
to a collision, but may not accept been, causes alike frames to be received, occasionally causing
application access to abort and routers to lose acquaintance relationships.