- About this Manual
- Chapter 1, Overview
- Chapter 2, CTC Operations
- Chapter 3, Initial Configuration
- Chapter 4, Configuring Interfaces
- Chapter 5, Configuring Bridging
- Chapter 6, Configuring STP and RSTP
- Chapter 7, Configuring VLANs
- Chapter 8, Configuring 802.1Q and Layer 2 Protocol Tunneling
- Chapter 9, Configuring Link Aggregation
- Chapter 10, Configuring Networking Protocols
- Chapter 11, Configuring IRB
- Chapter 12, Configuring VRF Lite
- Chapter 13, Configuring Quality of Service
- Chapter 14, Configuring the Switching Database Manager
- Chapter 15, Configuring Access Control Lists
- Appendix A, Command Reference
- Appendix B Cisco IOS Commands Not Supported in ML-Series Card Software
- Appendix C, Using Technical Support
Configuring Bridging
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
Bridging
The ML-Series card can be configured to serve as an IP router and a bridge. Cisco IOS software supports transparent bridging for Fast Ethernet, Gigabit Ethernet, and POS. Cisco IOS software functionality combines the advantages of a spanning-tree bridge and a router. This combination provides 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.
•In interface configuration mode:
–Determine which interfaces belong to the same bridge group.
These interfaces become part of the same spanning tree, allowing the ML-Series card 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 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.
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 bridge protocol data units (BPDUs) it receives on only its member interfaces.
Configuring Bridging
1 This command only needs to be executed once per card. It does not need to be executed separately for each bridge group on the card. 2 This step is not done for integrated routing and bridging (IRB). |
Configuring Bridging Example
Figure 5-1 illustrates an example of bridging.
Figure 5-1 Bridging Example
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
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:
Router# 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
Router# 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
Router# show spanning-tree
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