Describing the STP. Enhancements to STP. Configuring PortFast. Describing PortFast. Configuring. Verifying

Transcription

1 Enhancements to STP Describing the STP PortFast Per VLAN Spanning Tree+ (PVST+) Rapid Spanning Tree Protocol (RSTP) Multiple Spanning Tree Protocol (MSTP) MSTP is also known as Multi-Instance Spanning Tree Protocol (MISTP) on Cisco Catalyst 6500 switches and above Per VLAN Rapid Spanning Tree (PVRST) 2003, Cisco Systems, Inc. All rights reserved , Cisco Systems, Inc. All rights reserved. BCMSN v Describing PortFast Configuring PortFast Configuring spanning-tree portfast (interface command) or spanning-tree portfast default (global command) enables PortFast on all nontrunking ports Verifying show running-config interface fastethernet 1/1 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

2 Rapid Spanning Tree Protocol RSTP Port States 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v RSTP Port States RSTP Port Roles STP Port State RSTP Port State Port Included in Active Topology? Port Learning MAC Addresses? Disabled Discarding No No Blocking Discarding No No Listening Discarding No No Learning Learning No Yes Forwarding Forwarding Yes No 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

3 What Are Edge Ports? RSTP Link Types Will never have a switch connected to it Immediately transitions to forwarding Functions similarly to PortFast Configured by issuing the spanning-tree portfast command 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v RSTP BPDU Flag Byte Use RSTP Proposal and Agreement Process 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

4 Downstream RSTP Proposal and Agreement RSTP Topology Change Mechanism Root and switch A synchronize. Ports on A come out of sync. Proposal or agreement takes place between A and B. 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v PVRST Implementation Commands How to Implement Rapid PVRST Configuring spanning-tree mode rapid-pvst Verifying show spanning-tree vlan 101 Debugging debug spanning-tree 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

5 Verifying PVRST Summary Switch# show spanning-tree vlan 30 VLAN0030 Spanning tree enabled protocol rstp Root ID Priority Address 00d0.047b.2800 This bridge is the root Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority (priority sys-id-ext 30) Address 00d0.047b.2800 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 Interface Role Sts Cost Prio.Nbr Type Gi1/1 Desg FWD P2p Gi1/2 Desg FWD P2p Gi5/1 Desg FWD P2p RSTP provides faster convergence than 802.1D STP when topology changes occur. RSTP defines three port states: discarding, listening, and forwarding. RSTP defines five port roles: root, designated, alternate, backup, and disabled. Edge ports forward while topology changes occur. RSTP makes use of two link types P2P and shared w uses the BPDU differently from 802.1D. Convergence results from the proposal and agreement process conducted switch by switch. The RSTP topology change notification process differs from 802.1D. Various commands are used to configure and verify PVRST. PVRST enables RSTP while still maintaining PVST. Display spanning tree mode is set to PVRST. 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Multiple Spanning Tree Protocol Implementing MSTP Instance 1 maps to VLANs Instance 2 maps to VLANs , Cisco Systems, Inc. All rights reserved , Cisco Systems, Inc. All rights reserved. BCMSN v

6 MST Regions Extended System ID in Bridge ID Field MST configuration on each switch: Name Revision number VLAN association table 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Interacting Between MST Regions and 802.1D Configuring MSTP Switch(config)#spanning-tree mst configuration Enters MST configuration submode Switch(config-mst)#name name Sets the MST region name Switch(config-mst)#revision rev_num Sets the MST configuration revision number Switch(config-mst)#instance inst vlan range Maps the VLANs to an MST instance Switch(config-mst)#spanning-tree mst instance_number root primary secondary Establishes primary and secondary roots for MST instance 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

7 Verifying MSTP Verifying MSTP (Cont.) Switch#show spanning-tree mst configuration Displays MSTP configuration information Switch#show spanning-tree mst configuration Name [cisco] Revision 1 Instance Vlans mapped Switch#show spanning-tree mst instance_number Displays configuration information for a specific MSTP instance Switch#show spanning-tree mst 1 ###### MST01 vlans mapped: 1-10 Bridge address 00d0.00b priority (32768 sysid 1) Root this switch for MST01 Interface Role Sts Cost Prio.Nbr Status Fa4/4 Back BLK P2p Fa4/5 Desg FWD P2p Fa4/48 Boun FWD P2p Bound(STP) Switch#clear spanning-tree detected-protocols [interface interface-id] Forces renegotiation with neighboring switches during migration process 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Summary MSTP reduces the encumbrance of PVST by allowing a single instance of spanning tree to run for multiple VLANs. An MST region is a group of MSTP switches that appears as a single virtual bridge to adjacent CST and MSTP regions. Extended system ID ensures that VLAN ID or MSTP instance can be carried in the Bridge ID field of a BPDU. An MSTP region requires an IST and an arbitrary number of MSTP instances as it connects to an 802.1Q network at the MST region border. MSTP is configured with a unique set of commands. MSTP implementation requires configuration and verification using specific configuration and show commands. Configuring Link Aggregation with EtherChannel 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. 2-28

8 EtherChannel Dynamic Trunk Negotiation Protocols Logical aggregation of similar links Load balances Viewed as one logical port Redundancy PAgP Cisco proprietary LACP IEEE 802.3ad standard 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v About EtherChannel Configuration Commands Configuring Layer 2 EtherChannel Configure PAgP interface port-channel {channel-group-number} channel-protocol pagp channel-group 1 mode {mode} Verify show interfaces fastethernet 0/1 etherchannel show etherchannel 1 port-channel show etherchannel 1 summary Switch(config)#interface range interface slot/port - port Specifies the interfaces to configure in the bundle Switch(config-if-range)#channel-protocol {pagp lacp} Specifies the channel protocol either PAgP or LACP Switch(config-if-range)#channel-group number mode {active on auto desirable passive} Creates the port-channel interface and places the interfaces as members 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

9 Configuring Layer 3 EtherChannel Verifying EtherChannel Switch(config)#interface port-channel port-channel-number Creates a port-channel interface Switch(config-if)#no switchport Switch(config-if)#ip address address mask Specifies L3 and assigns an IP address and subnet mask to the EtherChannel Switch(config)#interface interface slot/port Specifies an interface to configure Switch(config-if)#no switchport Switch(config-if)#channel-group number mode {auto desirable on} Configures the interface as L3 and specifies the port channel and the PAgP mode Switch#show running-config interface port-channel num Displays port-channel information Switch#show running-config interface interface x/y Displays interface information Switch#show run interface port-channel 1 Building configuration... Current configuration : 66 bytes! interface Port-channel1 switchport mode dynamic desirable end Switch#show run interface gig 0/9 Building configuration... Current configuration : 127 bytes! interface GigabitEthernet 0/9 switchport mode dynamic desirable channel-group 2 mode desirable channel-protocol pagp end 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Verifying EtherChannel (Cont.) Guidelines for Configuring EtherChannel Switch#show interfaces gigabitethernet 0/9 etherchannel Port state = Up Mstr In-Bndl Channel group = 1 Mode = Desirable-Sl Gcchange = 0 Port-channel = Po2 GC = 0x Pseudo port-channel = Po1 Port index = 0 Load = 0x00 Flags: S - Device is sending Slow hello. C - Device is in Consistent state. A - Device is in Auto mode. P - Device learns on physical port. d - PAgP is down. Timers: H - Hello timer is running. Q - Quit timer is running. S - Switching timer is running. I - Interface timer is running. Local information: Hello Partner PAgP Learning Group Port Flags State Timers Interval Count Priority Method Ifindex Gi0/9 SC U6/S7 H 30s Any 15 Partner's information: Partner Partner Partner Partner Group Port Name Device ID Port Age Flags Cap. Gi0/9 DSW e.4780 Gi0/9 18s SC Age of the port in the current state: 00d:20h:00m:49s 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

10 Guidelines for Configuring EtherChannel (Cont.) EtherChannel Guidelines Switch#show run interface FastEthernet0/9 description DSW121 0/ DSW122 0/9-10 switchport trunk encapsulation dot1q switchport trunk allowed vlan 1,21-28 switchport mode trunk switchport nonegotiate duplex full speed 100 channel-group 2 mode desirable! interface FastEthernet0/10 description DSW121 0/ DSW122 0/9-10 switchport trunk encapsulation dot1q switchport trunk allowed vlan 1,21-28 switchport mode trunk switchport nonegotiate duplex full speed 100 channel-group 2 mode desirable 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v EtherChannel Load Balancing Configuring EtherChannel Load Balancing Switch(config)#port-channel load-balance type Configures EtherChannel load balancing Switch(config)# port-channel load-balance src-mac Switch#show etherchannel load-balance Source XOR Destination IP address 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

11 Summary EtherChannel increases bandwidth and provides redundancy by aggregating individual links between switches. EtherChannel can be dynamically configured between switches using either PAgP or LACP. Etherchannel is configured and verified using a variety of show commands. Best practices should be followed for EtherChannel configuration. EtherChannel load balances traffic over all the links in the bundle. Implementing Inter-VLAN Routing 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved Problem: Isolated Broadcast Domains Solution: Routing Between VLANs Because of their nature, VLANs inhibit communication between VLANs. Communications between VLANs requires a Layer 3 services module. 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

12 Inter-VLAN Routing with External Router Inter-VLAN Routing External Router Configuration Commands Configure on subinterface encapsulation dot1q (or isl) 10 ip address Verify show vlan 10 show ip route Single trunk link carries traffic for multiple VLANs to and from router. 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Inter-VLAN Routing on External Router: 802.1Q Trunk Link Inter-VLAN Routing on External Router: ISL Trunk Link 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

13 Verifying Inter-VLAN Routing Verifying the Inter-VLAN Routing Configuration Router#show vlan Displays the current IP configuration per VLAN Router#show ip route Displays IP route table information Router#show ip interface brief Displays IP address on interfaces and current state of interface The ping command tests connectivity to remote hosts. 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Explaining Multilayer Switching Defining Flows p3 p2 p1 Multilayer Switched Environment Host A Conventional Environment Host B 1 First Packet Host A 2 Host B Subsequent Packets Each packet of a traditional flow must be processed by the router The first packet of an MLS flow is processed by the router; all subsequent packets are switched 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

14 Layer 2 Switch Forwarding Process Logical Packet Flow for a Multilayer Switch 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Internal Router Processor Software/Hardware Requirements MLS Components Route Switch Module (RSM) Cisco IOS Release 11.3(2)WA4(4) or Later MLS-RP Multilayer Switching Route Processor RSM Cisco 85xx OR 75XX 72XX 4XXX MLS-SE Multilayer Switching Switch Engine Catalyst 2926G, 5000, or 6000 Series Switch Supervisor Engine III, FSX, III FLX, IIG, or IIIG Module Supervisor Engine Software Release 4.1(1) or Later NetFlow Feature Card (NFFC), NFFC II MLSP Multilayer Switching Protocol Multicast Hello Messages sent to MLS-SE by MLS-RP to Inform: MAC addresses used on different VLANs Routing/access lists changes occurring on MLS-RP 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

15 MLS-RP Advertisement Receiving MLSP Hello Messages Hello Message Hello Message Hello Message I am not a Layer 3 Switch but I will still pass on the message. MLS-RP sends out multicast hello messages Messages contain MAC, VLAN, and route information Messages use the CGMP multicast well-known address All switches receive the hello message Layer 3 switches process the hello message IP multicast passes transparently through non- Cisco switches 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Establishing an MLS Cache Entry Candidate Packet L3 Information Source IP = Destination IP = L2 Information Source MAC = 0010.f663.d000 Destination MAC = Cache Entry? A 0010.f663.d The MLS-SE receives initial frame 2 The MLS-SE reads and recognizes the destination MAC Address 3 The MLS-SE checks the MLS cache for like entries 4 The MLS-SE forwards the frame to the MLS-RP 2003, Cisco Systems, Inc. All rights reserved. BCMSN v B 0090.b Establishing an MLS Cache Entry (cont.) Enable Packet L3 Information Source IP = Destination IP = L2 Information Source MAC = Destination MAC = 0090.b A 0010.f663.d , Cisco Systems, Inc. All rights reserved. BCMSN v B 0090.b The MLS-RP receives the frame and consults the routing table 6 The MLS-RP rewrites the header with the new destination MAC address 7 The MLS-RP enters its own MAC address for the source address The MLS-RP forwards the frame to the MLS-SE

16 Switching Subsequent Frames in a Flow Incoming Frame L3 Information Source IP = Rewritten Frame Destination IP = L3 Information L2 Information Source IP = Destination IP = Source MAC = 0010.f663.d000 Destination MAC = L2 Information A B Source MAC = Destination MAC = 0090.b f663.d b Destination IP Source IP Port DstPrt SrcPrt Destination Mac Vlan Port UDP b /9 MLS Cache Entry IP Unicast Frame and Packet Rewrite Incoming IP Unicast Packet Rewritten IP Unicast Packet The MLS-SE receives subsequent frames in the flow The MLS-SE compares the incoming frame with the MLS cache entry The MLS-SE rewrites the frame header The MLS-SE forwards the frame to the destination 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Improving IP Routing Performance with MLS MLS Topology Example 1 In this section we discuss the following topics: Multilayer Switching Fundamentals Configuring the Multilayer Switch Route Processor Applying Flow Masks Configuring the Multilayer Switch Switching Engine MLS Topologies Topology Examples Topology Quiz Unsupported Topology Topology Changes and Routing Impacts 2003, Cisco Systems, Inc. All rights reserved. BCMSN v A 1 2 R2 R1 3 MLS-SE MLS-RP R2 1 Host A sends a packet to the default gateway 2 R1 rewrites the frame header to reflect the destination as the next-hop router (R2) 3 MLS-SE forwards the frame to R2 4 R2 rewrites the frame header to reflect the destination as Host B 5 MLS-SE forwards the frame to Host B 6 All subsequent frames are switched 2003, Cisco Systems, Inc. All rights reserved. BCMSN v B

17 MLS Topology Example 2 Quiz: MLS Topology Example 1 Host A sends a packet to the default gateway 2 MLS-SE1 forwards the frame to MLS-SE2 3 MLS-SE2 forwards the frame to MLS-SE3 4 MLS-SE3 forwards the frame to MLS-RP1 5 MLS-RP1 rewrites the frame header and forwards the frame to MLS-SE3 6 MLS-SE3 forwards the frame to MLS-SE2 7 MLS-SE2 forwards the frame to MLS-SE1 A 8 MLS-SE1 forwards the frame to Host B 9 All subsequent frames are switched through MLS-SE1 10 Entries in MLS-SE2 and 3 time out MLS-RP MLS-SE3 MLS-SE2 MLS-SE1 2003, Cisco Systems, Inc. All rights reserved. BCMSN v B S4 A S2 S1 S5 MLS-RP Port in Blocking State 2003, Cisco Systems, Inc. All rights reserved. BCMSN v S6 S3 B S7 Original MLS path was A S4 S2 S1 S3 S7 B Spanning tree blocked the link between S1 and S3 What is the next available MLS path? X Answer: MLS Topology Example Unsupported MLS Topology S1 MLS-RP Port in blocking state X RSM1 VLAN41 VLAN42 RSM2 S2 S3 S4 A S5 S6 B S7 A B First packet path = A S4 S2 S1 S2 S3 S7 B Subsequent packet path = A S4 S2 S3 S7 B 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

18 Unsupported MLS Topology Solution 1 Unsupported MLS Topology Solution 2 VLAN 41 VLAN 42 VLAN 41 VLAN 42 MLS-RP 1 MLS-RP 2 MLS-RP 1 MLS-RP 2 ISL Link MLS-SE 1 MLS-SE 2 Link 1 MLS-SE 1 Link 2 MLS-SE 2 A B A B Configure an ISL link from MLS-SE1 to MLS-RP1 to carry both VLAN41 and VLAN , Cisco Systems, Inc. All rights reserved. BCMSN v Configure a second link from MLS-SE1 to MLS-RP1 to route for Subnet , Cisco Systems, Inc. All rights reserved. BCMSN v CAM Table Requires an exact match on all bits Matching is a binary operation: 0 or 1 Provides very high-speed lookups TCAM Table Matches only significant values Matches based on three values: 0, 1, or X (either) Masks used to wildcard some content fields 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

19 Summary SVI on a Multilayer Switch A router on a stick can be used to route between VLANs using either ISL or 802.1Q as the trunking protocol. A router on a stick requires subinterfaces, one for each VLAN. Verify inter-vlan routing by generating IP packets between two subnets. Multilayer switches can forward traffic at both Layer 2 and Layer 3. Multilayer switches rewrite the Layer 2 and Layer 3 header using tables held in hardware. Configure ip routing interface vlan 10 ip address router eigrp 50 network Verify show ip route 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Configuring Inter-VLAN Routing Through an SVI Routed Ports on a Multilayer Switch (Cont.) Step 1 : Configure IP routing. Switch(config)#ip routing Step 2 : Create an SVI interface. Switch(config)#interface vlan vlan-id Step 3 : Assign an IP address to the SVI. Switch(config-if)#ip address ip-address mask Step 4 : Configure the IP routing protocol if needed. Switch(config)#router ip_routing_protocol <options> 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v

20 Routed Ports on a Multilayer Switch Configuring a Routed Port Physical switch port with Layer 3 capability Not associated with a VLAN Requires removal of Layer 2 port functionality Configure ip routing interface fa0/1 no switchport ip address router eigrp 50 network Step 1 : Configure IP routing. Switch(config)#ip routing Step 2 : Create a routed port. Switch(config-if)#no switchport Step 3 : Assign an IP address to the routed port. Switch(config-if)#ip address ip-address mask Step 4 : Configure the IP routing protocol if needed. Switch(config)#router ip_routing_protocol <options> 2003, Cisco Systems, Inc. All rights reserved. BCMSN v , Cisco Systems, Inc. All rights reserved. BCMSN v Summary SVI is a VLAN of switch ports represented by one interface to the routing system. Specific commands are used to configure and verify routing on multilayer switch interfaces. The interface vlan command creates the SVI. A routed port has Layer 3 attributes. A routed port requires the removal of Layer 2 port functionality with the no switchport command. To receive dynamic updates, a routing protocol is required. 2003, Cisco Systems, Inc. All rights reserved. BCMSN v