cc/td/doc/product/atm/c8540/12_0/13_19
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Table of Contents

Troubleshooting Layer 2 Interfaces
Layer 2 Switching and Bridging Overview
Troubleshooting Layer 2 Switching
Troubleshooting Integrated Routing and Bridging
Troubleshooting Trunk Port Problems
Troubleshooting Fast EtherChannel Problems

Troubleshooting Layer 2 Interfaces


This chapter provides troubleshooting information about connectivity and performance problems in the Layer 2 network connections of an ATM switch router and includes the following sections:

Layer 2 Switching and Bridging Overview

This section provides some overview information about Layer 2 switching and bridging.

Layer 2 Switching

The difference between Layer 2 and Layer 3 switching is the type of information inside the frame that is used to determine the correct output interface. With Layer 2 switching, frames are switched based on MAC address information. With Layer 3 switching, frames are switched based on network-layer information.

Layer 2 switching does not look inside a packet for network-layer information as does Layer 3 switching. Layer 2 switching is performed by looking at a destination MAC address within a frame. It looks at the frame destination address and sends it to the appropriate interface if the switch knows the destination address location. Layer 2 switching builds and maintains a switching table that keeps track of which MAC addresses belong to each port or interface.

If the Layer 2 switch does not know where to send the frame, it broadcasts the frame out to all its ports on the network, to learn the correct destination. When the frame reply is returned, the switch learns the location of the new address, and adds the information to the switching table.

The switch router performs Layer 2 switching using the following functions:

Bridging

Cisco IOS software supports transparent bridging for Ethernet. In addition, Cisco supports all the mandatory Management Information Base (MIB) variables specified for transparent bridging in RFC 1286.

Cisco IOS software bridging functionality combines the advantages of a spanning tree bridge and a full multiprotocol router. This combination provides the speed and protocol transparency of an adaptive spanning tree bridge, along with the functionality, reliability, and security of a router.

The switch router can be configured to serve as both an IP and IPX router and a MAC-level bridge, bridging any traffic that cannot otherwise be routed. For example, a router routing IP traffic can also bridge the Digital local-area transport (LAT) protocol or NetBIOS traffic.

To configure bridging, you must perform the following tasks:

These interfaces will be part of the same spanning tree. This allows the switch router to bridge all nonrouted traffic among the network interfaces comprising the bridge group. Interfaces not participating in a bridge group cannot forward bridged traffic.

If the packet's destination address is known in the bridge table, it is forwarded on a single interface in the bridge group. If the packet's destination is unknown in the bridge table, it is flooded on all forwarding interfaces in the bridge group. The bridge places source addresses in the bridge table as it learns them during the process of bridging.

A separate spanning tree process runs for each configured bridge group. Each bridge group participates in a separate spanning tree. A bridge group establishes a spanning tree based on the BPDUs it receives on only its member interfaces.

Troubleshooting Layer 2 Switching

This section describes Layer 2 Switching troubleshooting and includes the following sections:

Layer 2 Switching Broadcasts

Figure 12-1 shows the broadcast process all interfaces use to update all the other CAM tables in the bridge group using the following processes:


Figure 12-1   Layer 2 Switching Broadcasts Used to distribute CAM Updates


Following is the process the switch uses to learn the MAC addresses as show in Figure 12-2:

1. Interface module microcode learns a new MAC Address

2. Interface module microcode sends an IPC to the route processor to update the bridging table

3. Aged entries are removed from the CAM

4. Interface module microcode sends an IPC to the route processor to remove the aged entry from bridging tables

Layer 2 unknown unicast switching is accomplished by the following:


Figure 12-2   Layer 2 Learning Process


Bridging over Fast EtherChannel

MAC address learning in the switch router occurs differently depending on the IOS version installed.

For Cisco IOS Release 12.0(4a)W5(11a) and earlier, MAC address learning occurs as follows:

For Cisco IOS Release 12.0(5)W5(13) and later, MAC address learning occurs as follows:

Troubleshooting Layer 2 Switching

To troubleshoot a Layer 2 switching problems, use the following commands:

Command Purpose

show bridge group

Displays bridge group configuration and status information.

show bridge

Displays the status of all the bridge groups on the switch router.

show spanning-tree number

Displays the spanning tree topology for a bridge group.

show interfaces bvi number

Displays BVI interface configuration, status, and statistics. Use this command when the BVI is part of a bridge group.

show interfaces {fastethernet | gigabitethernet} slot/subslot/port
(on the ingress interface)

Displays interface configuration, status, and statistics on the ingress interface.

show interfaces {fastethernet | gigabitethernet} slot/subslot/port
(on the egress interface)

Displays interface configuration, status, and statistics on the egress interface.

show switch bridge-table entry

Displays bridge table entry summary.

show epc freecam interface {fastethernet | gigabitethernet} slot/subslot/port

Displays information about free space in the content addressable memory.

show epc if-entry interface {fastethernet | gigabitethernet} slot/subslot/port all

Displays all interface entry information for the specific interface.

show epc patricia interface {fastethernet | gigabitethernet} slot/subslot/port mac detail (on the ingress interface)

Displays the MAC patricia tree for the ingress interface.

show epc patricia interface {fastethernet | gigabitethernet} slot/subslot/port mac detail (on the egress interface)

Displays the MAC patricia tree for the egress interface.

As stated before, once the first interface learns a new destination address, source address, and VLAN, that information must be broadcasts to all other interfaces to allow them to update their CAM. That information is broadcast using the Broute VC to communicate with ports on other modules in the same bridge group. Figure 12-3 shows interface Fast Ethernet 0/0/0 using broadcast VC 0 to broadcast an update (to the CAM) to interfaces Fast Ethernet 0/0/1 and 0/0/2.


Figure 12-3   Broadcasting CAM Updates


To confirm that Broute VC 0 is up, use the show atm vc cast p2mp interface fastethernet slot/subslot/port command as shown in the following example.

Switch# show atm vc cast p2mp interface fastethernet 0/0/0
Interface          VPI   VCI   Type X-Interface X-VPI X-VCI Encap Status
FastEthernet0/0/0   0    202   PVC FastEthernet0/0/1 0 227         UP
                                       FastEthernet0/0/2 0 228         UP

Using the cross-connect VCI information from the previous output, confirm that Broute VC 0 is configured on the other interfaces in the bridge group use the show atm vc traffic interface fastethernet slot/subslot/port 0 X-VCI command as shown in the following examples:

Switch# show atm vc traffic interface fastethernet 0/0/0 0 202
Interface VPI VCI Type rx-cell-cnts tx-cell-cnts
FastEthernet 0 202 PVC 0 0
Switch# show atm vc traffic interface fastethernet 0/0/1 0 227
Interface VPI VCI Type rx-cell-cnts tx-cell-cnts
FastEthernet 0 227 PVC 0 0
Switch# show atm vc traffic interface fastethernet 0/0/2 0 228
Interface VPI VCI Type rx-cell-cnts tx-cell-cnts
FastEthernet 0 228 PVC 0 0

Figure 12-4 is an example network of two Layer 2 switches, and is used in the following troubleshooting steps.


Figure 12-4   Layer 2 Troubleshooting Example Network


The following are the processes used to troubleshoot Layer 2 switching connections:

To troubleshoot Layer 2 switching, perform the following steps:


Step 1   Use the show spanning-tree command to display bridge group information as shown in Figure 12-4.

Switch# show spanning-tree 1
Bridge group 1 is executing the IEEE compatible Spanning Tree protocol
.
(Information Deleted)
.
Port 43 (FastEthernet12/0/1) of Bridge group 1 is forwarding
.
(Information Deleted)
.
Port 58 (GigabitEthernet11/0/1.1 ISL) of Bridge group 1 is forwarding

Step 2   Find the entries in the show spanning-tree command output for the interfaces in question and check the Port fields to confirm the ports at Fast Ethernet12/0/1 and Gigabit Ethernet 11/0/1.1 ISL are forwarding.

Step 3   Use the show bridge command to display bridge group information.

Switch# show bridge 1
.
(Information Deleted)
.
Bridge Group 1:
Address     Action     Interface
0010.e3aa.aaaa   forward    Fa12/0/1
0090.21bb.bbbb   forward    Gi11/0/1.1

Find the entries for those interfaces in the show bridge command output. Note the Address fields to see that the MAC addresses being forwarded to the Fast Ethernet12/0/1 and Gigabit Ethernet 11/0/1.1 ISL connections are in the bridge table. These addresses are used in the following step.

Step 4   Use the show epc mac interface FastEthernet interface command with the MAC address parameter. Add the MAC address being forwarded to interface FastEthernet 12/0/1.

Switch# show epc mac interface FastEthernet 12/0/1 0010.e3aa.aaaa
MACaddr:0010.e3aa.aaaa    IF Number:43 MAC Local

Note the IF Number field; in this example, the number is "43." You will need this number in the following command.

Step 5   Use the show epc mac interface GigabitEthernet interface command with the MAC address parameter. Add the MAC address being forwarded to interface GigabitEthernet 11/0/1.1 ISL.

Switch# show epc mac interface FastEthernet 12/0/1 0090.21bb.bbbb
MACaddr:0090.21bb.bbbb     IF Number:58

Note the IF Number field; in this example, the number is "58." You will need this number in the following command.

Step 6   Use the show epc patricia interface FastEthernet interface command with the mac detail parameters.

Switch# show epc patricia interface FastEthernet 12/0/1 mac detail
.
(Information Deleted)
.
7# MAC addr:0090.21bb.bbbb   IF Number:58 Entry:Remote
Learned 10450 times used
CAM location: 101D
8# MAC addr:0010.e3aa.aaaa   IF Number:43 Entry:Local
Learned 0 times used
CAM location: 0FF8
Total number of MAC entries: 8

Step 7   Verify that the information from this command is consistent with the command outputs in Step 5.

If there are inconsistencies or non-zero invalid entries in the tables, you can use the clear bridge command to rebuild the tables.

Step 8   Check the Entry field.

Interface Number 58 has learned of this entry via the flooding from IF Number 42 and it is marked as Remote. Interface number 43 has learned these entries as local entries, which is typical bridge behavior.


Note   Entries marked as MyMac are for internal use. These are static entries and are for spanning tree BPDUs and CDP. The MAC address marked as HSRP is the actual BIA Mac address of the port. This entry is only present if there is a BVI defined for that bridge group.

Verify that the information from the show epc patricia command output is consistent with the command outputs in Step 4.

If there are inconsistencies or non-zero invalid entries in the tables, you can use the clear bridge command to rebuild the tables.


Caution   Use the clear bridge command carefully. It causes a temporary increase in switch router activity which can lead to traffic disruptions.

Step 9   Use the show epc patricia interface GigabitEthernet interface command with the vlan number and details parameters.

Switch# show epc patricia interface GigabitEthernet 11/0/1 vlan 1 detail
15# MAC addr:0090.21bb.bbbb   IF Number:58 Entry:Local
Learned 0 times used
CAM location: 1034
16# MAC addr:0010.e3aa.aaaa   IF Number:43 Entry:Remote
Learned 6029 times used
CAM location: 101B

Step 10   Check the Entry field. The Entry field descriptions are the same as those in Step 8.

Verify that the information from the show epc patricia command output is consistent with the command outputs in Step 4.

If there are inconsistencies or non-zero invalid entries in the tables, you can use the clear bridge command to rebuild the tables.

Step 11   Use the show epc if-entry interface FastEthernet interface entry GigabitEthernet interface.subinterface command to display the CAM table entry.

Switch# show epc if-entry interface FastEthernet 12/0/1 entry GigabitEthernet 11/0/1.1
IF Entry for GigabitEthernet11/0/1.1 on FastEthernet12/0/1
Mac(hex) - 00:90:21:dd:dd:dd
isMyInteface : False isSubInterface : True
      Status Up Broute VC - 662 Bcast VC - 747
Netmask: 32
FEC disabled
ISL, Vlan 1
      State : Forwarding
Bridge-Group enabled
      IP routing off bridging on
      IPX routing off bridging on
      Appletalk routing off
In Encapsulation:
ICMP Redirect disabled Unreachable disabled
IP Multicast disabled: ttl-threshold: 0

Step 12   Confirm the following:

Step 13   Use the same command again but with the interface entries reversed.

Switch# show epc if-entry interface GigabitEthernet 11/0/1.1 entry FastEthernet 12/0/1
IF Entry for FastEthernet12/0/1 on GigabitEthernet11/0/1
Mac(hex) - 00:90:21:cc:cc:cc
isMyInteface : False isSubInterface : False
      Status Up Broute VC - 622 Bcast VC - 747
Netmask: 32
FEC disabled
Trunking Disabled
      State : Forwarding
Bridge-Group enabled
      IP routing off bridging on
      IPX routing off bridging on
      Appletalk routing off
In Encapsulation:
ICMP Redirect disabled Unreachable disabled
IP Multicast disabled: ttl-threshold: 0

Step 14   Confirm the following:

Troubleshooting Layer 2 connections differs from troubleshooting Layer 3 connections in the following ways:

Refer to the Layer 3 Software Feature and Configuration Guide if any changes are necessary to the configuration of the interface.



Other Layer 2 Switching Problems

This sections describes the following, less common, Layer 2 switching connection problems:

Layer 2 Connection is Flooding

If you determine the Layer 2 connection is flooding instead of switching, check the following:

Packets are Switched but are Not Appearing on the Wire

If you are sure the packets are being switched but the connection does not appear on the wire, try the following:

Layer 2 CAM Display

You might need to check for a specific MAC address on an interface. If so, use the show epc patricia interface {FastEthernet | GigabitEthernet} card/subcard/port mac command. The following is an example with a description of some useful MAC addresses:

Switch# show epc patricia interface fastethernet 0/0/0 mac
1# MAC addr:0000.0000.0000          VC:0     Entry:
2# MAC addr:0900.2b01.0001 MyMAC VC:4 Entry:
3# MAC addr:0180.c200.0000 MyMAC VC:4 Entry:
4# MAC addr:0100.0ccc.cccc  MyMAC VC:4 Entry:
5# MAC addr:0010.073d.8207 HsrpMAC  VC:4 Entry:
6# MAC addr:0008.e0bc.4190 MyMAC VC:4 Entry:
Total number of MAC entries: 6

In this example check the following:

Check for Spanning Tree Loop

The spanning-tree algorithm in the IOS software is probably not the source of the spanning tree loop. The spanning-tree loop probably exists because of a problem in the end-to-end connectivity. Try one of the following tests to confirm you do not have a spanning-tree loop:

If the spanning tree MAC address is not in the output, then spanning tree is the problem.

Refer to the Layer 3 Software Feature and Configuration Guide if any changes are necessary to the configuration of the interface.



Layer 2 Bridging Troubleshooting Commands

To troubleshoot a Layer 2 bridging problem, use the following commands:

Command Purpose

show bridge group

Displays bridge group configuration and status information.

show bridge

Displays the status of all the bridge groups on the switch router.

show spanning-tree number

Displays the spanning tree topology for a bridge group.

show interfaces bvi number

Displays BVI interface configuration, status, and statistics. Use this command when the BVI is part of a bridge group.

show interfaces {fastethernet | gigabitethernet} slot/subslot/port
(on the ingress interface)

Displays interface configuration, status, and statistics on the ingress interface.

show interfaces {fastethernet | gigabitethernet} slot/subslot/port
(on the egress interface)

Displays interface configuration, status, and statistics on the egress interface.

show switch bridge-table entry

Displays bridge table entry summary.

show epc freecam interface {fastethernet | gigabitethernet} slot/subslot/port

Displays information about free space in the content addressable memory.

show epc if-entry interface {fastethernet | gigabitethernet} slot/subslot/port all

Displays all interface entry information for the specific interface.

show epc patricia interface {fastethernet | gigabitethernet} slot/subslot/port mac detail (on the ingress interface)

Displays the MAC patricia tree for the ingress interface.

show epc patricia interface {fastethernet | gigabitethernet} slot/subslot/port mac detail (on the egress interface)

Displays the MAC patricia tree for the egress interface.

If a BVI is involved, use the following commands:

Command Purpose

show bridge group

Displays bridge group configuration and status information.

show interfaces irb

Displays integrated routing and bridging configuration and status for all interfaces.

show smf

Displays software MAC address information.

show interfaces bvi number

Displays BVI interface information.

show bridge number group

Displays the status of the member ports in the specified bridge group.

show bridge number

Displays the status of the bridge group.

show epc patricia interface {fastethernet | gigabitethernet} slot/subslot/port mac detail

Displays the MAC patricia tree for the specified interface physical interface in the bridge group with a problem.

Troubleshooting Integrated Routing and Bridging

This section describes troubleshooting Integrated Routing and Bridging (IRB) on the Catalyst 8510 MSR and Catalyst 8540 MSR and Catalyst 8510 CSR and Catalyst 8540 CSR switches.

Your network may require you to bridge local traffic within several segments while having hosts on the bridged segments reach the hosts or routers on routed networks. For example, if you are migrating bridged topologies into routed topologies, you may want to start by connecting some of the bridged segments to the routed networks.

IP Switching with IRB Overview

Using the IRB feature, you can route a given protocol between routed interfaces and bridge groups within a single switch router. Specifically, local or unroutable traffic will be bridged among the bridged interfaces in the same bridge group, while routable traffic will be routed to other routed interfaces or bridge groups.

Because bridging is in the data-link layer (Layer 2) and routing is in the network layer (Layer 3), they have different protocol configuration models. With IP, for example, bridge group interfaces belong to the same network and have a collective IP network address. In contrast, each routed interface represents a distinct network and has its own IP network address. Integrated routing and bridging uses the concept of a Bridge-Group Virtual Interface (BVI) to enable these interfaces to exchange packets for a given protocol.

A BVI is a virtual interface within the campus switch router that acts like a normal routed interface. A BVI does not support bridging, but it actually represents the corresponding bridge group to routed interfaces within the switch router. The interface number is the link between the BVI and the bridge group.

Layer 3 switching software supports the routing of IP and IPX between routed interfaces and bridged interfaces in the same router, in both fast-switching and process-switching paths.


Note   BVIs do not support IP multicast routing.

Before Configuring IRB

Consider the following before configuring IRB:

Troubleshooting IRB Connections

To troubleshoot the IRB configuration, use the following commands:

Command Purpose

show interfaces bvi interface-name

Displays BVI information, such as the BVI MAC address and processing statistics.

show interfaces irb

Displays the following BVI information:

  • Protocols that this bridged interface can route to the other routed interface if this packet is routable
  • Protocols that this bridged interface bridges
  • Entries in the software MAC-address filter

Troubleshooting IRB is a combination of both Layer 2 and Layer 3 troubleshooting. Check the following:

When using these processes be aware of the following differences:

Follow these steps to troubleshoot the status of an IRB configuration:


Step 1   Use the show interface bvi number command to check the configuration and status of the BVI.

Switch# show interface bvi 1
BVI1 is up, line protocol is up
Hardware is BVI, address is 0000.0ccb.292c (bia 0000.0000.0000)
  Internet address is 172.20.52.123/29
MTU 1500 bytes, BW 10000 Kbit, DLY 5000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
ARP type: ARPA, ARP Timeout 04:00:00
Queueing strategy: fifo
Output queue 0/0, 0 drops; input queue 0/75, 0 drops
Switch#

Step 2   Check the BVI field. It should indicate up.

Step 3   Check the Internet address field. It should include a valid address for routing.

Step 4   Use the show interface irb command to check the configuration and status of the IRB connections.

Switch# show interface irb
ATM0/0/0
.
(Information Deleted)
.
FastEthernet3/0/5
Routed protocols on FastEthernet3/0/5:
ip
Bridged protocols on FastEthernet3/0/5:
appletalk clns ip ipx
Software MAC address filter on FastEthernet3/0/5
Hash Len Address Matches Act Type
0x00: 0 ffff.ffff.ffff 0 RCV Physical broadcast
0x1D: 0 0090.2156.d83c 0 RCV Interface MAC address
0x20: 0 0000.0ccb.292c 0 RCV Bridge-group Virtual Interface
0x2A: 0 0900.2b01.0001 0 RCV DEC spanning tree
0xC0: 0 0100.0ccc.cccc 1185 RCV CDP
0xC1: 0 0100.0ccc.cccd 0 RCV SSTP MAC address
0xC2: 0 0180.c200.0000 0 RCV IEEE spanning tree
0xC2: 1 0180.c200.0000 0 RCV IBM spanning tree
0xC2: 2 0100.0ccd.cdce 0 RCV VLAN Bridge STP
FastEthernet3/0/6
.
(Information Deleted)
.
BVI1
Routed protocols on BVI1:
ip
Tunnel0
Switch#



If you determine that IRB is configured incorrectly, refer to the "Configuring Bridging" chapter in the Layer 3 Switching Feature and Configuration Guide .

Troubleshooting Trunk Port Problems

The switch router software provides several show commands that can be used for troubleshooting.

Troubleshooting Trunk Port Problems

To troubleshoot trunk port problems, use the following command:

Command Purpose

show epc patricia interface {fastethernet | gigabitethernet} slot/subslot/port vlan vlan detail

Displays the patricia tree information for the specified VLAN (for each VLAN on trunk).

Troubleshooting Fast EtherChannel Problems

This section describes troubleshooting Fast EtherChannel problems and includes the following:

Bridging Over Fast EtherChannel Overview

Ether Channel is a trunking technology that groups together multiple full-duplex 802.3 Ethernet interfaces to provide fault-tolerant, high-speed links between switches, routers, and servers. EtherChannel is a logical aggregation of multiple Ethernet interfaces. EtherChannel forms a single higher bandwidth routing or bridging endpoint. EtherChannel is designed primarily for host-to-switch connectivity or Inter-Switch Link (ISL) switch-to-switch connectivity (for example, connectivity to a Catalyst 5500 switch).

In summary, EtherChannel provides the following benefits:

The EtherChannel interface (consisting of up to four Ethernet interfaces) is treated as a single interface, which is called a port channel. You must configure EtherChannel on the EtherChannel interface rather than on the individual member Ethernet interfaces. You create the EtherChannel interface by using the interface port-channel interface configuration command. The switch router supports up to 64 port channels.

EtherChannel connections are fully compatible with Cisco IOS VLAN and routing technologies. The ISL VLAN trunking protocol can carry multiple VLANs across an EtherChannel, and routers attached to EtherChannel links can provide full multiprotocol routing with support for host standby using Host Standby Router Protocol (HSRP).

Your switch router supports Fast EtherChannel (FEC) and Gigabit EtherChannel (GEC).

Cisco Fast EtherChannel technology builds upon standards-based 802.3 full-duplex Fast Ethernet to provide a reliable high-speed solution for the campus network backbone. Fast EtherChannel provides bandwidth scalability within the campus by providing increments of 200 Mbps to 800 Mbps.

Cisco Gigabit EtherChannel technology provides bandwidth scalability within the campus by providing increments of 2 Gbps to 8 Gbps.


Note   EtherChannel does not support IP/IPX filtering at Layer 3 with the ACL daughter card.


Note   For more detailed information about EtherChannel, refer to the "Configuring LAN Interfaces" chapter in the C isco IOS Interface Configuration Guide.

Troubleshooting Bridging Over Fast EtherChannel

To troubleshoot the EtherChannel status and configuration, use the following commands:

Command Purpose

show interfaces port-channel number

Displays the status of the physical interface.

show epc fe-channel interface {fastethernet | gigabitethernet} slot/subslot/port channel port-channel number

Displays all EPC interface information for the specific interface and port channel.

show epc if-entry interface {fastethernet | gigabitethernet} slot/subslot/port entry port-channel number

Displays interface entry information for the specific interface.

Follow these steps to troubleshoot the EtherChannel status and configuration:


Step 1   Use the show interfaces port-channel number command to confirm the EtherChannel status and configuration.

Switch# show interfaces port-channel 1
Port-channel1 is up, line protocol is up
  Hardware is FEChannel, address is 0010.073c.0513 (bia 0000.0000.0000)
MTU 1500 bytes, BW 300000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Unknown duplex, Unknown Speed
ARP type: ARPA, ARP Timeout 04:00:00
No. of active members in this channel: 3
Member 0 : FastEthernet1/0/4 , Full-duplex, 100Mb/s
Member 1 : FastEthernet1/0/6 , Full-duplex, 100Mb/s
Member 2 : FastEthernet1/0/7 , Full-duplex, 100Mb/s
Last input 00:00:00, output never, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/120, 0 drops; input queue 0/225, 0 drops
5 minute input rate 13000 bits/sec, 17 packets/sec
5 minute output rate 2000 bits/sec, 1 packets/sec
24335602 packets input, 2345055668 bytes
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 0 abort
0 watchdog, 0 multicast
0 input packets with dribble condition detected
1366573 packets output, 289782286 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
Switch#

Step 2   Check the Port-channel field. It should indicate up.

Step 3   Note the MAC address assigned to the port channel. It will be used in Step 4.

Step 4   Use the show epc if-entry interface command with the entry interface parameters to display the status of the Broute VCs.

Switch# show epc if-entry interface fastEthernet 1/0/4 entry port-channel 1
IF Entry for Port-channel1 on FastEthernet1/0/4
    Mac(hex) - 00:10:07:3C:05:13
isMyInteface : True isSubInterface : False
    Status Up Broute VC - 97 Bcast VC - 0
Netmask: 32
FEC enabled ( Flow-based Load-balancing )
Trunking Enabled
State : Not-Applicable/Listening/Blocking
Bridge-Group disabled
IP routing off bridging off
IPX routing off bridging off
Appletalk routing off
In Encapsulation:
ICMP Redirect enabled Unreachable enabled
IP Multicast disabled: ttl-threshold: 0
ACL Indexs:
Input ACL: 0 Output ACL: 0
ACL Flags:
Input IP: OFF Output IP: OFF
Input IPX: OFF Output IPX: OFF
Switch#

Step 5   Confirm that the MAC address in this step matches the MAC address displayed in Step 1.

For inconsistencies between the adjacency table and the EPC IP address table, use the clear arp or clear adjacencies command to rebuild the tables. When you use these commands, the router will send an ARP request for all entries in the ARP cache. As replies come back, it will refresh the cache. If any entries time out, they will be cleared from the table. The router will then build the adjacency table using this information, and populate the interface EPC IP address table.

Step 6   Use the show epc if-entry interface command with the entry interface parameters to display the status of the VCs.

Switch# show epc fe-channel interface fastEthernet 1/0/4 channel port-channel 1
FEC Group (Port-channel1) Information on FastEthernet1/0/4
Member 0 VC - 97
Member 1 VC - 177
Member 2 VC - 217
Member 3 VC - 217
Member Ship BitMap 0x7
Switch#



If you determine that the EtherChannel interface is configured incorrectly, refer to the "Configuring EtherChannel" chapter in the Layer 3 Switching Feature and Configuration Guide .


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Posted: Wed Jan 22 00:29:21 PST 2003
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