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Chapter 18 Configuring Transparent Bridging and Integrated Routing and Bridging.

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Presentation on theme: "Chapter 18 Configuring Transparent Bridging and Integrated Routing and Bridging."— Presentation transcript:

1 Chapter 18 Configuring Transparent Bridging and Integrated Routing and Bridging

2 Objectives Upon completion of this chapter, you will be able to perform the following tasks: Configure transparent bridging Configure Integrated Routed and Bridging (IRB)

3 Transparent Bridging Configuration

4 Transparent Bridging overview  Three major functions — Learning — Forwarding/filtering frames — Loop avoidance E0E1

5 How Bridges Learn Hosts’ Locations  Source MAC address associated with interface E0E1 E0: c E0: c E1: c E1: c Bridging Table c c c c

6 How Bridges Forward Frames  Occurs when destination is known E0E1 E0: c E0: c E1: c c c c c E1: c

7 How Bridges Filter Frames  Occurs when destination is known to exist on source’s segment E0E1 E0: c E1: c E1: c c c c c E0: c X

8 Topological Loops  Bridging loops can cause problems X Y Segment 1 Segment 2 Broadcast

9 Loop Avoidance  Spanning-tree algorithm disables interfaces X Y X

10 Transparent Configuration Tasks  Global configuration – Select a spanning-tree protocol – Assign a priority to the bridge Interface configuration –Assign the interface to a spanning-tree group –Assign a cost to the outgoing interface TB

11 Transparent Commands  Selects the spanning tree protocol Router (config) # bridge bridge-group protocol {ieee | dec} Router (config-if) # bridge bridge-group Assigns an interface to a bridge group Bridge group 1 E0 E1 E2 E3 E4 E5 bridge 1 protocol ieee int e 0 bridge-group 1 int e 1 bridge-group1 int e 3 bridge-group 1 bridge 1 protocol ieee int e 0 bridge-group 1 int e 1 bridge-group1 int e 3 bridge-group 1

12 Spanning -Tree Commands  Assigns a priority to the bridge Router (config) # bridge bridge-group priority number Router (config-if) # bridge-group bridge-group path-cost cost Assigns a cost to use the outgoing interface

13 Transparent Bridging Example bridge 1 protocol dec bridge 1 priority 100 interface ethernet 0 bridge-group 1 bridge-group 1 path-cost 10 interface ethernet 1 bridge-group 1 bridge-group 1 path-cost 10 bridge 1 protocol dec bridge 1 priority 100 interface ethernet 0 bridge-group 1 bridge-group 1 path-cost 10 interface ethernet 1 bridge-group 1 bridge-group 1 path-cost 10 E0 E1 Cisco B Cisco D Cisco A E0 E1 Cisco C Cisco E E0E1 Segment 1 bridge 1 protocol dec bridge 1 priority 1 interface ethernet 0 bridge-group 1 interface ethernet 1 bridge-group 1 bridge 1 protocol dec bridge 1 priority 1 interface ethernet 0 bridge-group 1 interface ethernet 1 bridge-group 1

14 Verifying Transparent Bridging Router# show bridge Total of 300 station blocks, 295 free BG Hash Address Action Int. Age RX count TX count 1 09/ C forward E / C forward E CA/0 AA CC forward E Router# Router# show bridge Total of 300 station blocks, 295 free BG Hash Address Action Int. Age RX count TX count 1 09/ C forward E / C forward E CA/0 AA CC forward E Router# 1 00/0 FFFF.FFFF.FFFF discard - P 0 0

15 Verifying Spanning Tree Router# show span Bridge Group 1 is executing the IEEE compatible spanning tree protocol IEEE bridge domains are not used for this bridge group Bridge Identifier has priority 32768, address 000.0c00.ab40 Configured hello time 2, max age 20, forward delay 15 We are the root of the spanning tree Acquisition of new addresses is enabled LAT service filtering is disabled Topology change flag not set, detected flag not set Times:hold 1, topology change 30, notification 30 hello 2, max age 20, forward delay 15 Timers: hello 2, topology change 0, notification 0 Port 9 (Ethernet2) bridge group 1, forwarding. Path cost 100, priority 0 Designated root has priority 32768, address c00.ab40 Designated bridge has priority 32768, address c00.ab40 Designated port is 1, path cost 0 Timers: message age 0, forward delay 0, hold 0 Router# show span Bridge Group 1 is executing the IEEE compatible spanning tree protocol IEEE bridge domains are not used for this bridge group Bridge Identifier has priority 32768, address 000.0c00.ab40 Configured hello time 2, max age 20, forward delay 15 We are the root of the spanning tree Acquisition of new addresses is enabled LAT service filtering is disabled Topology change flag not set, detected flag not set Times:hold 1, topology change 30, notification 30 hello 2, max age 20, forward delay 15 Timers: hello 2, topology change 0, notification 0 Port 9 (Ethernet2) bridge group 1, forwarding. Path cost 100, priority 0 Designated root has priority 32768, address c00.ab40 Designated bridge has priority 32768, address c00.ab40 Designated port is 1, path cost 0 Timers: message age 0, forward delay 0, hold 0

16 Integrated Routing and Bridging Configuration

17 IRB Overview  Packets received on bridged interface can be routed through routed interface  Packets received on routed interface can be routed through bridged interface Bridge GroupRouted Interface

18 IRB Uses  Interconnect bridged and routed topologies  Conserve network address  Increase performance by bridging local traffic

19 IRB Operation  Bridge-Group Virtual Interface (BVI) represents a bridge groupt to a routing domain BVI Bridge Group 20

20 BVI Addressing  Gets MAC addresses from an interface in the bridge group  Requires network-layers address configuration Bridge Group 20 BVI 20 MAC Address = Bridge ID IP Address =

21 Bridging or Routing Decision  Destination MAC is router’s-route packet BVI = BVI’s MACA’s MACB’s NetworkA’s Network Destination Source E0 MACB’s MACB’s NetworkA’s Network 2 1 E

22 IRB Configuration Tasks Configure bridge groups and routed interfaces 1. Enable IRB 2. Configure the BVI 3. Enable the BVI to accept routed packets 4. Enable routing on the BVI for desired protocols 1. Enable bridging 2. Assign bridge groups to interfaces 3. Configure routing for desired protocols Task 1 Task 2 Configure IRB and the BVI

23 Configuring IRB and the BVI Example interface Ethernet 1 ip address ! interface Ethernet 2 bridge-group 20 ! interface Ethernet 3 bridge-group 20 ! interface BVI 20 ip address ! bridge irb bridge 20 protocol ieee bridge 20 route ip interface Ethernet 1 ip address ! interface Ethernet 2 bridge-group 20 ! interface Ethernet 3 bridge-group 20 ! interface BVI 20 ip address ! bridge irb bridge 20 protocol ieee bridge 20 route ip Bridge Group 20 BVI 20 IP Address = E E2 E3

24 Enabling Routing on the Bridge Group Bridge Group 1 BVI 1 AT Address = 33.1 E E2 E Bridge Apple Talk (AT) Route IP Bridge everything else Route Apple Talk (AT) Route IP

25 Enabling Routing and Bridging Example appletalk routing ! interface Ethernet 1 ip address appletalk cable-range appletalk zone ozone ! interface Ethernet 2 ip address bridge-group 1 ! interface Ethernet 3 ip address bridge-group 1 ! interface BVI 1 no ip address appletalk cable-range appletalk zone no parking ! bridge irb bridge 1 protocol ieee bridge 1 route appletalk bridge 1 route ip no bridge 1 bridge ip appletalk routing ! interface Ethernet 1 ip address appletalk cable-range appletalk zone ozone ! interface Ethernet 2 ip address bridge-group 1 ! interface Ethernet 3 ip address bridge-group 1 ! interface BVI 1 no ip address appletalk cable-range appletalk zone no parking ! bridge irb bridge 1 protocol ieee bridge 1 route appletalk bridge 1 route ip no bridge 1 bridge ip AppleTalk routing is enabled. IP routing is enabled by default. IP is only routed on all interfaces BVI enabled to route and bridge AppleTalk. It will not perform IRB on IP. Bridge everything except IP. BVI 1 associated with E2 and E3 because they are in bridge group 1.

26 Configuration Considerations  IRB bridges all protocols by default, so routing must be explicitly enabled for packets that require routing  Do not configure any protocol attributes on the bridge interfaces when both routing and bridging a given protocol  Do not configure bridging attributes on the BVI  Determine whether you need to redefine the BVI’s MTU size

27 Verifying IRB Operation Router# show interface bvi1 MTU 1500 bytes, BW Kbit, DLY 5000 usec, rely 255/255, load 1/255 Encapsulation ARPA, loopback not set, keepalive set (10 sec) ARP type: ARPA, ARP Timeout 04:00:00 Last input 00:00:04, output 00:00:01, output hang never Last clearing of “show interface” counters never Output queue 0/40, 0 drops; input queue 0/75, 0 drops 5 minute input rate 0 bits/sec, 1 packets/sec 5 minute output rate 0 bits/sec, 1 packets/sec 345 packets input, bytes, 0 no buffer Received 151 broadcasts, 0 runts, 0 giants 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 input packets with dribble condition detected 578 packets output, bytes, 0 underruns 1 output errors, 0 collisions, 1 interface resets 0 babbles, 0 late collision, 0 deferred 1 lost carrier, 0 no carrier 0 output buffer failures, 0 output buffers swapped out Router# show interface bvi1 MTU 1500 bytes, BW Kbit, DLY 5000 usec, rely 255/255, load 1/255 Encapsulation ARPA, loopback not set, keepalive set (10 sec) ARP type: ARPA, ARP Timeout 04:00:00 Last input 00:00:04, output 00:00:01, output hang never Last clearing of “show interface” counters never Output queue 0/40, 0 drops; input queue 0/75, 0 drops 5 minute input rate 0 bits/sec, 1 packets/sec 5 minute output rate 0 bits/sec, 1 packets/sec 345 packets input, bytes, 0 no buffer Received 151 broadcasts, 0 runts, 0 giants 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 input packets with dribble condition detected 578 packets output, bytes, 0 underruns 1 output errors, 0 collisions, 1 interface resets 0 babbles, 0 late collision, 0 deferred 1 lost carrier, 0 no carrier 0 output buffer failures, 0 output buffers swapped out BVI1 is up, line protocol is up Hardware is BVI, address is c (bia )

28 Verifying IRB Operation (cont.) Router# show interfaces ethernet 2 irb appletalk ip appletalkclnsdecnetvines apollo ipx xns Software MAC address filter on Ethernet2 Hash LenAddress Matches ActType 0x00: 0ffff.ffff.ffff 4886 RCVPhysical broadcast 0x1F: e2b.a RCVInterface MAC address 0x1F: e2b.a2210 RCVBridge-group Virtual Interface 0x2A: b RCVDEC spanning tree 0xA5: a20RCVAppletalk zone 0xC2: c RCVIEEE spanning tree 0xF8: ff.ffff2110RCVAppletalk broadcast Router# show interfaces ethernet 2 irb appletalk ip appletalkclnsdecnetvines apollo ipx xns Software MAC address filter on Ethernet2 Hash LenAddress Matches ActType 0x00: 0ffff.ffff.ffff 4886 RCVPhysical broadcast 0x1F: e2b.a RCVInterface MAC address 0x1F: e2b.a2210 RCVBridge-group Virtual Interface 0x2A: b RCVDEC spanning tree 0xA5: a20RCVAppletalk zone 0xC2: c RCVIEEE spanning tree 0xF8: ff.ffff2110RCVAppletalk broadcast Ethernet2 Routed protocolson Ethernet2: Bridged protocolson Ethernet2:

29 Summary Transparent bridging is predominantly used in Ethernet environments Spanning-tree algorithm eliminates loops IRB is used in the following situations: To migrate a bridged network to a routed network To connect a remote site that does not have routing capabilities To conserve IP, IPX, and Apple Talk addresses To increase performances by keeping local bridged traffic local


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