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Table Of Contents
Monitoring and Verifying Bridging
Configuring Bridges
This chapter describes how to configure bridging for the ML-Series card. For more information about the Cisco IOS commands used in this chapter, refer to the Cisco IOS Command Reference publication.
This chapter includes the following major sections:
• Monitoring and Verifying Bridging
Caution Cisco Inter-Switch Link (ISL) and Cisco Dynamic Trunking Protocol (DTP) are not supported by the ML-Series cards, but the ML-Series broadcast forwards these formats. Using ISL or DTP on connecting devices is not recommended. Some Cisco devices attempt to use ISL or DTP by default.
Understanding Bridging
The ML-Series card supports transparent bridging for Fast Ethernet, Gigabit Ethernet and POS ports. It supports a maximum of 255 active bridge groups. Transparent bridging combines the speed and protocol transparency of a spanning-tree bridge, along with the functionality, reliability, and security of a router.
To configure bridging, you must perform the following tasks in the modes indicated:
•In global configuration mode:
–Enable bridging of IP packets.
–Select the type of Spanning Tree Protocol (STP) (optional).
•In interface configuration mode:
–Determine which interfaces belong to the same bridge group.
The ML-Series card bridges all nonrouted traffic among the network interfaces comprising the bridge group. If spanning tree is enabled, the interfaces became part of the same spanning tree. Interfaces not participating in a bridge group cannot forward bridged traffic.
If the destination address of the packet is known in the bridge table, the packet is forwarded on a single interface in the bridge group. If the packet's destination is unknown in the bridge table, the packet 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.
Spanning tree is not mandatory for an ML-Series card bridge group. But if it is configured, a separate spanning-tree process runs for each configured bridge group. A bridge group establishes a spanning tree based on the bridge protocol data units (BPDUs) it receives on only its member interfaces. The ML-Series card has a 255 active bridge group maximum.
Configuring Bridging
Use the following steps to configure bridging:
Figure 6-1 shows a bridging example. Example 6-1 shows the code used to configure ML-Series A. Example 6-2 shows the code used to configure ML-Series B.
Figure 6-1 Bridging Example
Example 6-1 Router A Configuration
bridge 1 protocol ieee
!
!
interface FastEthernet0
no ip address
bridge-group 1
!
interface POS0
no ip address
crc 32
bridge-group 1
pos flag c2 1
Example 6-2 Router B Configuration
bridge 1 protocol ieee
!
!
interface FastEthernet0
no ip address
bridge-group 1
!
interface POS0
no ip address
crc 32
bridge-group 1
pos flag c2 1
Monitoring and Verifying Bridging
After you have set up the ML-Series card for bridging, you can monitor and verify its operation by performing the following procedure in privileged EXEC mode:
Example 6-3 shows an example of the monitoring and verifying bridging.
Example 6-3 Monitoring and Verifying Bridging
ML-Series# show bridge
Total of 300 station blocks, 298 free
Codes: P - permanent, S - self
Bridge Group 1:
Maximum dynamic entries allowed: 1000
Current dynamic entry count: 2
Address Action Interface
0000.0001.6000 forward FastEthernet0
0000.0001.6100 forward POS0
ML-Series# show bridge verbose
Total of 300 station blocks, 298 free
Codes: P - permanent, S - self
Maximum dynamic entries allowed: 1000
Current dynamic entry count: 2
BG Hash Address Action Interface VC Age RX count TX co
unt
1 60/0 0000.0001.6000 forward FastEthernet0 -
1 61/0 0000.0001.6100 forward POS0 -
Flood ports
FastEthernet0
POS0
ML-Series# show spanning-tree brief
Bridge group 1
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 0005.9a39.6634
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 0005.9a39.6634
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0 Desg FWD 19 128.3 P2p
PO0 Desg FWD 9 128.20 P2p
Posted: Mon Dec 3 02:58:46 PST 2007
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