CCNA_642-802_ICND3000_Improving_Performance

1、 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-1Medium-Sized Switched Network Construction Improving Performance with Spanning Tree 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-2Outline Learning Addresses Transmitting Frames EtherChannel Introducing STP Terminology Introducing

2、 Spanning Tree Protocol Overview STP electoral process Spanning Tree Port States Spanning Tree Path Costs Spanning Tree Recalculation Rapid Spanning Tree Protocol Summary 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-3 Station D sends a broadcast frame. Broadcast frames are flooded to all

3、 ports except the originating port.Broadcast Frames 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-4Transmitting Frames 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-5Interconnection TechnologiesTechnologyUseFast EthernetConnects end-user devices to the access layer switchGigabi

4、t EthernetConnects access switch to distribution switch and high use servers to switches 10-Gigabit EthernetProvides high-speed switch to switch links, backbonesEtherChannelProvides high-speed switch to switch links, backbones with redundancy 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-

5、6Determining Equipment and Cabling NeedsEach link provides adequate bandwidth for the total aggregate traffic over that link. 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-7Advantages of EtherChannel Logical aggregation of similar links between switches Load-shares across links Viewed as

6、one logical port to STP Redundancy 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-8Redundant Topology Redundant topology eliminates single points of failure. Redundant topology causes broadcast storms, multiple frame copies, and MAC address table instability problems. 2007 Cisco Systems, I

7、nc. All rights reserved.ICND2 v1.02-9Broadcast Storms Host X sends a broadcast. Switches continue to propagate broadcast traffic over and over. 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-10Multiple Frame Copies Host X sends a unicast frame to router Y. The MAC address of router Y has n

8、ot been learned by either switch. Router Y will receive two copies of the same frame. 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-11 Host X sends a unicast frame to router Y. The MAC address of router Y has not been learned by either switch. Switches A and B learn the MAC address of hos

9、t X on port 1. The frame to router Y is flooded. Switches A and B incorrectly learn the MAC address of host X on port 2.MAC Database Instability 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-12 Provides a loop-free redundant network topology by placing certain ports in the blocking state

10、Published in the IEEE 802.1D specification Enhanced with the Cisco PVST+ implementationLoop Resolution with STP 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-13Spanning-Tree Operation One root bridge per broadcast domain. One root port per nonroot bridge. One designated port per segment.

11、Nondesignated ports are unused. 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-14Spanning-Tree Operation1. 每個(gè)網(wǎng)絡(luò)都有一個(gè)根網(wǎng)橋，根網(wǎng)橋上所有端口都是指定端口2. 每一個(gè)非根網(wǎng)橋，都有一個(gè)根端口3. 每一個(gè)直連網(wǎng)段上有一個(gè)指定端口;指定端口的選取通過以下三點(diǎn)依次判斷： 1）到根網(wǎng)橋根路徑成本最低 （cost） 2）所在網(wǎng)橋ID小 (bridgeID) 3）端口ID小 （PortID）4. 非指定端口就為阻塞端口Dp用于發(fā)送根橋BPDU ; RP接收根橋BPDU 200

12、7 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-15STP Root Bridge Selection BPDU (default = sent every 2 seconds) Root bridge = bridge with the lowest bridge ID Bridge ID =BridgePriorityMACAddress 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-16Spanning-Tree Path CostLink SpeedCost

13、(Revised IEEE Specification)Cost (Previous IEEE Specification)10 Gb/s211 Gb/s41100 Mb/s191010 Mb/s100100 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-17Spanning-Tree Operation Example 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-18Spanning-Tree Recalculation 2007 Cisco System

14、s, Inc. All rights reserved.ICND2 v1.02-19Spanning tree transits each port through several different states:Spanning-Tree Port States 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-20Describing PortFastPortFast is configured on access ports, not trunk ports. 2007 Cisco Systems, Inc. All ri

15、ghts reserved.ICND2 v1.02-21Configuring and Verifying PortFastspanning-tree portfastSwitchX(config-if)# Configures PortFast on an interfacespanning-tree portfast defaultSwitchX(config)# Enables PortFast on all non-trunking interfacesshow running-config interface interfaceSwitchX# Verifies that PortF

16、ast has been configured on an interfaceOR 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-22uplinkfastUplinkfast當(dāng)鏈路失效時(shí)，它可以用來改進(jìn)STP的收斂時(shí)間。 Uplinkfast允許在主鏈路失效前，找到根橋的可選路徑，當(dāng)主鏈路失效時(shí)，備份鏈路更快的啟用端口不會(huì)等待50秒的收斂時(shí)間 如果你正在用802.1d STP,而且接入層有冗余鏈路肯定就需要打開Uplinkfast配置上行速鏈路 Switch(config)#spanning-tree uplinkfast 2

17、007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-23 backbonefast 當(dāng)某條鏈路并沒有直連到失效的交換機(jī)，它會(huì)收到指定橋的一個(gè)次等BPDU,它就知道路徑中到根網(wǎng)橋路徑失效，這時(shí)使用BACKbonefast加速收斂。 backbonefast可以在所有catalyst交換機(jī)上啟用，以便檢測非直連的鏈路失效，它能更快速啟用生成樹50秒的默認(rèn)時(shí)間，它能節(jié)省20秒配置主干快速 switch(config)# spanning-tree backbonefast 2007 Cisco Systems, Inc. All right

18、s reserved.ICND2 v1.02-24快速生成樹（快速生成樹（RSTP）802.1W 交換式網(wǎng)絡(luò)（不論交換機(jī)品牌），有沒好的STP運(yùn)行，內(nèi)置了之前討論過的加快收斂特性并啟用在每臺(tái)交換機(jī)上呢？歡迎進(jìn)入RSTP的世界 Cisco創(chuàng)建了portfast,uplinkfast,backbonefast來修補(bǔ)802.1D的漏洞，這些需要額外配置，802.1W將這些“問題”封包解決了，只要打開RSTP就可以了快速生成樹配置 switch(config)#spanning-tree mode rstp 2007 Cisco Systems, Inc. All rights reserved.IC

19、ND2 v1.02-25Rapid Spanning Tree Protocol 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-26Rapid Spanning Tree Protocol (Cont.) 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-27Per VLAN Spanning Tree Plus 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-28PVST+ Extended Br

20、idge IDBridge ID without the extended system IDExtended bridge ID with system IDSystem ID = VLAN 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-29PVRST+ Configuration Guidelines1.Enable PVRST+.2.Designate and configure a switch to be the root bridge.3.Designate and configure a switch to be

21、 the secondary root bridge.4.Verify the configuration. 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-30Configuring the Root and Secondary Bridges 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-31PVRST+ Implementation Commandsspanning-tree mode rapid-pvstSwitchX(config)# Configur

22、es PVRST+show spanning-tree vlan vlan# detailSwitchX# Verifies the spanning-tree configurationdebug spanning-tree pvst+SwitchX# Displays PVST+ event debug messages 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-32Configuring the Root and Secondary Bridges: SwitchAspanning-tree vlan 1 root

23、primary This command forces this switch to be the root for VLAN 1.spanning-tree vlan 2 root secondary This command configures this switch to be the secondary root for VLAN 2.ORspanning-tree vlan # priority priority This command statically configures the priority (increments of 4096).SwitchA(config)#

24、SwitchA(config)#SwitchA(config)# 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-33Configuring the Root and Secondary Bridges: SwitchBspanning-tree vlan 2 root primary This command forces the switch to be the root for VLAN 2.spanning-tree vlan 1 root secondary This command configures the sw

25、itch to be the secondary root VLAN 1.ORspanning-tree vlan # priority priority This command statically configures the priority (increments of 4096).SwitchB(config)#SwitchB(config)#SwitchB(config)# 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-34Verifying PVRST+The spanning-tree mode is set

26、 to PVRST.SwitchX# show spanning-tree vlan 30 VLAN0030Spanning tree enabled protocol rstpRoot ID Priority 24606Address 00d0.047b.2800This bridge is the rootHello Time 2 sec Max Age 20 sec Forward Delay 15 secBridge ID Priority 24606 (priority 24576 sys-id-ext 30) Address 00d0.047b.2800Hello Time 2 s

27、ec Max Age 20 sec Forward Delay 15 secAging Time 300Interface Role Sts Cost Prio.Nbr Type- - - - - -Gi1/1 Desg FWD 4 128.1 P2pGi1/2 Desg FWD 4 128.2 P2pGi5/1 Desg FWD 4 128.257 P2p 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-35Per VLAN Spanning Tree Plus 2007 Cisco Systems, Inc. All rig

28、hts reserved.ICND2 v1.02-36PVST+ Extended Bridge IDBridge ID without the extended system IDExtended bridge ID with system IDSystem ID = VLAN多生成樹情況下每個(gè)網(wǎng)橋?qū)?yīng)每個(gè)vlan的優(yōu)先級會(huì)作不同的設(shè)置， 便于針對每一個(gè)VLAN來定義網(wǎng)橋的優(yōu)先級 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-37PVRST+ Configuration Guidelines1.Enable PVRST+.2

29、.Designate and configure a switch to be the root bridge.3.Designate and configure a switch to be the secondary root bridge.4.Verify the configuration. 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-38PVRST+ Implementation Commandsspanning-tree mode rapid-pvstSwitchX(config)# Configures PVR

30、ST+show spanning-tree vlan vlan# detailSwitchX# Verifies the spanning-tree configurationdebug spanning-tree pvst+SwitchX# Displays PVST+ event debug messages 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-39Verifying PVRST+The spanning-tree mode is set to PVRST.SwitchX# show spanning-tree

31、vlan 30 VLAN0030Spanning tree enabled protocol rstpRoot ID Priority 24606Address 00d0.047b.2800This bridge is the rootHello Time 2 sec Max Age 20 sec Forward Delay 15 secBridge ID Priority 24606 (priority 24576 sys-id-ext 30) Address 00d0.047b.2800Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

32、Aging Time 300Interface Role Sts Cost Prio.Nbr Type- - - - - -Gi1/1 Desg FWD 4 128.1 P2pGi1/2 Desg FWD 4 128.2 P2pGi5/1 Desg FWD 4 128.257 P2p 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-40Configuring the Root and Secondary Bridges 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.0

33、2-41Configuring the Root and Secondary Bridges: SwitchAspanning-tree vlan 1 root primary This command forces this switch to be the root for VLAN 1.spanning-tree vlan 2 root secondary This command configures this switch to be the secondary root for VLAN 2.ORspanning-tree vlan # priority priority This

34、 command statically configures the priority (increments of 4096).SwitchA(config)#SwitchA(config)#SwitchA(config)# 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-42Configuring the Root and Secondary Bridges: SwitchBspanning-tree vlan 2 root primary This command forces the switch to be the r

35、oot for VLAN 2.spanning-tree vlan 1 root secondary This command configures the switch to be the secondary root VLAN 1.ORspanning-tree vlan # priority priority This command statically configures the priority (increments of 4096).SwitchB(config)#SwitchB(config)#SwitchB(config)# 2007 Cisco Systems, Inc

36、. All rights reserved.ICND2 v1.02-43Default Spanning-Tree Configuration Cisco Catalyst switches support three types of STPs: PVST+ PVRST+ MSTP The default STP for Cisco Catalyst switches is PVST+ : A separate STP instance for each VLAN One root bridge for all VLANs No load sharing 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-44生成樹協(xié)議生成樹協(xié)議STP / RSTP 開天辟地的第一代生成樹協(xié)議，基于端口，單生成樹協(xié)議PVST / PVST+ 聰明伶俐的第二代生成樹協(xié)議，基于VLA