Implementing Inter-VLAN Routing

Transcription

1 Internetwork Communications C:>ping Implementing Inter-VLN Routing Can two hosts on different subnets communicate without a router? No What would happen if a host tried to ping another host? They could not communicate. Would it send an RP Request? Why or why not? The host would not send an RP Request because there is no defaultgateway. 2003, Cisco Systems, Inc. ll rights reserved , Cisco Systems, Inc. ll rights reserved. CMSN v Internetwork Communications InterVLN Routing External Router VLN VLN 2 VLN 3 Router on a stick VLNs, 2, 3 Trunk Multilayer Switch VLN VLN 2 VLN 3 Or Trunk 2003, Cisco Systems, Inc. ll rights reserved. CMSN v External Router Router(config)# inter fa 0/ Router(config-if) ip address Router(config)# inter fa 0/2 Router(config-if) ip address Router(config)# inter fa 0/3 Router(config-if) ip address , Cisco Systems, Inc. ll rights reserved. CMSN v

2 Inter-VLN Routing External Router Configuration Commands Inter-VLN Routing on External Router: 802.Q Trunk Link Configure on subinterface encapsulation dotq (or isl) 0 ip address Verify show vlan 0 show ip route Router on a stick VLNs, 2, 3 Trunk 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v Inter-VLN Routing on External Router: ISL Trunk Link Verifying Inter-VLN Routing The ping command tests connectivity to remote hosts. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

3 Verifying the Inter-VLN Routing Configuration Router#show vlan Displays the current IP configuration per VLN Router#show ip route Displays IP route table information Router#show ip interface brief Multilayer Switching Displays IP address on interfaces and current state of interface 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. 2-0 Explaining Multilayer Switching 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

4 Multilayer Switch Interfaces Layer 2: ccess or Trunk Ports Multilayer Switch Interfaces Layer 2: ccess or Trunk Ports Logical Interface (SVI) Physical Interface Logical Interface (SVI-L3) Physical Interface (L3) DLS# show interface gig 0/2 switchport Name: Gig0/2 Switchport: Enabled <output omitted> 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v Multilayer Switch Interfaces Layer 3 Port Configuration Physical Interfaces DLS(config)# interface gig 0/ DLS(config-if)# no switchport DLS(config-if)# ip address DLS2(config)# interface gig 0/ DLS2(config-if)# no switchport DLS2(config-if)# ip address If in Layer 3 mode switchport interface command puts the port into Layer 2 mode. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

5 Physical Interfaces and EtherChannel Switch(config)# interface port-channel 5 Switch(config-if)# no switchport Switch(config-if)# ip address Switch(config)# interface port-channel 5 Switch(config-if)# no switchport Switch(config-if)# ip address If several interfaces are bundled together using EtherChannel the IP address is assigned to the port-channel interface, not the individual physical links. To configure Layer 3 EtherChannels,: First you must create the port-channel logical interface Then you add the Ethernet ports into the port-channel 2003, Cisco Systems, Inc. ll rights reserved. CMSN v What about EtherChannel Interfaces? Port-channel 5 Port-channel Fa 0/ Fa 0/ Fa 0/2 Fa 0/2 Switch(config)# interface port-channel 5 Switch(config-if)# no switchport Switch(config-if)# ip address Switch(config)# interface range fa 0/ - 2 Switch(config-if-range)# no ip address Switch(config-if-range)# no switchport Switch(config-if-range)# channel-group 5 mode active Switch(config)# interface port-channel 5 Switch(config-if)# no switchport Switch(config-if)# ip address Switch(config)# interface range fa 0/ - 2 Switch(config-if-range)# no ip address Switch(config-if-range)# no switchport Switch(config-if-range)# channel-group 5 mode active First you must create the port-channel logical interface Then you add the Ethernet ports into the port-channel Using LCP in this example. Remember, the channel-group number is associated with the port-channel interface. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v SVI Interfaces - Logical Interfaces Switch(config)# vlan vlan-number Switch(config-vlan)# name vlan-name Switch(config)# interface vlan vlan-number Switch(config-if)# ip address ip-address mask Switch(config-if)# no shutdown Layer 3 functionality can also be enabled for an entire VLN. The IP address is assigned to the logical interface the VLN. This is needed when routing is required between VLNs. SVI (Switched Virtual Interface) No physical connection VLNs must be created before the SVI can be used. The IP address associated of the VLN interface is the default gateway of the workstation. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

6 Configuring a Routed Port Configuring Inter-VLN Routing Through an SVI Step : Configure IP routing. Switch(config)#ip routing Step 2 : Create a routed port. Switch(config-if)#no switchport Step 3 : ssign 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. ll rights reserved. CMSN v Step : Configure IP routing. Switch(config)#ip routing Step 2 : Create an SVI interface. Switch(config)#interface vlan vlan-id Step 3 : ssign 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. ll rights reserved. 22 CMSN v Routing Verifying Enable routing on DLS and DLS2. Configure EIGRP DLS and DLS2. Turn off auto-summarization DLS(config)# ip routing DLS(config)# router eigrp DLS(config-router)# network DLS(config-router)# network DLS(config-router)# no auto-summary DLS2(config)# ip routing DLS2(config)# router eigrp DLS2(config-router)# network DLS2(config-router)# network DLS2(config-router)# no auto-summary 2003, Cisco Systems, Inc. ll rights reserved. CMSN v DLS#show ip route Core Network.0.0.0/24 is subnetted, subnets D...0 [90/ ] via , 00:00:07, FastEthernet0/ /24 is subnetted, 5 subnets C is directly connected, Vlan0 C is directly connected, Vlan D [90/ ] via , 0:29:4, GigabitEthernet0/ DLS2 Networks (VLNs) D [90/ ] via , 0:29:4, GigabitEthernet0/ C is directly connected, Vlan /30 is subnetted, 3 subnets C is directly connected, GigabitEthernet0/ C is directly connected, FastEthernet0/ D [90/2846] via , 0:7:8, GigabitEthernet0/ DLS# Network between DLS2 and Core 2003, Cisco Systems, Inc. ll rights reserved. 24 CMSN v

7 Defining Flows - MLS Layer 2 Switch Forwarding Process p3 p2 p Multilayer Switched Environment Host Conventional Environment Host First Packet Host 2 Host 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. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v Logical Packet Flow for a Multilayer Switch Establishing an MLS Cache Entry Candidate Packet L3 Information Source IP = Destination IP = L2 Information Source MC = 000.f663.d000 Destination MC = Cache Entry? 000.f663.d The MLS-SE receives initial frame 2 The MLS-SE reads and recognizes the destination MC ddress 3 The MLS-SE checks the MLS cache for like entries 4 The MLS-SE forwards the frame to the MLS-RP 0090.b , Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

8 Establishing an MLS Cache Entry (cont.) Enable Packet L3 Information Source IP = Destination IP = L2 Information Source MC = Destination MC = 0090.b f663.d , Cisco Systems, Inc. ll rights reserved. CMSN v b The MLS-RP receives the frame and consults the routing table 6 The MLS-RP rewrites the header with the new destination MC address 7 The MLS-RP enters its own MC address for the source address The MLS-RP forwards the frame to the MLS-SE 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 MC = 000.f663.d000 Destination MC = L2 Information Source MC = Destination MC = 0090.b f663.d b Destination IP Source IP Port DstPrt SrcPrt Destination Mac Vlan Port UDP b /9 MLS Cache Entry 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. ll rights reserved. CMSN v IP Unicast Frame and Packet Rewrite Improving IP Routing Performance with MLS Incoming IP Unicast Packet Rewritten IP Unicast Packet In this section we discuss the following topics: Multilayer Switching Fundamentals Configuring the Multilayer Switch Route Processor pplying 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. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

9 MLS Topology Example MLS Topology Example 2 2 R2 R 3 MLS-SE MLS-RP R2 Host sends a packet to the default gateway 2 R 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 5 MLS-SE forwards the frame to Host 6 ll subsequent frames are switched 2003, Cisco Systems, Inc. ll rights reserved. CMSN v Host sends a packet to the default gateway MLS-SE forwards the frame to MLS-SE2 MLS-SE2 forwards the frame to MLS-SE3 MLS-SE3 forwards the frame to MLS-RP MLS-RP rewrites the frame header and forwards the frame to MLS-SE MLS-SE3 forwards the frame to MLS-SE2 MLS-SE2 forwards the frame to MLS-SE MLS-SE forwards the frame to Host ll subsequent frames are switched through MLS-SE 0 Entries in MLS-SE2 and 3 time out MLS-RP MLS-SE3 MLS-SE2 MLS-SE 2003, Cisco Systems, Inc. ll rights reserved. CMSN v MLS-RP dvertisement 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 MC, VLN, and route information Messages use the CGMP multicast well-known address ll switches receive the hello message Layer 3 switches process the hello message IP multicast passes transparently through non- Cisco switches 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

10 Quiz: MLS Topology Example nswer: MLS Topology Example S MLS-RP Port in locking State X S MLS-RP Port in blocking state X S2 S3 S2 S3 S4 S5 S6 S7 S4 S5 S6 S7 Original MLS path was S4 S2 S S3 S7 Spanning tree blocked the link between S and S3 What is the next available MLS path? 2003, Cisco Systems, Inc. ll rights reserved. CMSN v First packet path = S4 S2 S S2 S3 S7 Subsequent packet path = S4 S2 S3 S7 2003, Cisco Systems, Inc. ll rights reserved. CMSN v Unsupported MLS Topology Unsupported MLS Topology Solution VLN4 VLN42 RSM RSM2 VLN 4 VLN 42 MLS-RP MLS-RP 2 ISL Link MLS-SE MLS-SE 2 Configure an ISL link from MLS-SE to MLS-RP to carry both VLN4 and VLN , Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

11 Unsupported MLS Topology Solution 2 Summary VLN 4 VLN 42 MLS-RP Link Link 2 MLS-SE MLS-RP 2 MLS-SE 2 router on a stick can be used to route between VLNs using either ISL or 802.Q as the trunking protocol. router on a stick requires subinterfaces, one for each VLN. Verify inter-vln 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 a second link from MLS-SE to MLS-RP to route for Subnet , Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v Multilayer Switching Deploying CEF-ased Multilayer Switching Traditional MLS CEF-ased MLS Multilayer switching - ability of a Catalyst switch to support switching and routing of packets in hardware. Optional support for Layers 4 through 7 switching in hardware as well. route processor (or Layer 3 engine) must download software-based routing, switching, access lists, QoS, and other information to the hardware for packet processing. 2003, Cisco Systems, Inc. ll rights reserved , Cisco Systems, Inc. ll rights reserved. CMSN v

12 Traditional MLS RP Traditional MLS Dual effort between: Route Processor (RP) Switching Engine (SE) Traditional MLS: Route once, switch many Specialized pplication-specific Integrated Circuits (SICs) perform Layer 2 rewrite operations of routed packets: Source MC address Destination MC address Cyclic redundancy check (CRC). ecause the source and destination MC addresses change during Layer 3 rewrites, the switch must recalculate the CRC for these new MC addresses. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v SE SE: Listens in to the first packet going to the router (RP) and going from the router (RP). If the SE can switch the packet in both directions: It can learn a shortcut path for subsequent packets to use. Thus, bypassing the router (RP). This technique is also known as: Netflow-based switching. With traditional MLS, the Layer 3 engine (route processor) and switching SICs work together to build Layer 3 entries on the switch. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v Traditional MLS Candidate Packet Info Layer 3 Info S-IP D-IP Layer 2 Info S-MC D-MC C--- MLS- RP The Destination MC ddress is one of the router s interfaces. There is not an existing flow, so I will flag this as a candidate packet. MLS- SE dotq Tag (inside Eth. Hdr) VLN Ethernet Header IP Header IP Data D-MC= C--- S-MC= S-MC= S-IP = D-IP = dotq Tag (inside Eth. Hdr) VLN D-MC= C--- Ethernet Header IP Header IP Data S-MC= S-IP = D-IP = The switch forwards the first packet in any flow to the Layer 3 engine for processing using software switching/routing. fter the routing of the first packet in the flow, the Layer 3 engine programs the hardware-switching components for routing for subsequent packets. Workstation sends a packet to workstation, Workstation sends the packet to its default gateway (which is the RSM). Switch (MLS-SE) recognizes this packet as an MLS candidate packet because the destination MC address matches the MC address of the MLS router (MLS-RP). s a result, the switch creates a candidate entry for this flow. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

13 MLS- RP MLS- RP Candidate Packet Info MLS- SE Layer 3 Info S-IP D-IP Layer 2 Info S-MC D-MC C--- MLS- SE dotq Tag (inside Eth. Hdr) VLN 2 D-MC= Ethernet Header IP Header IP Data S-MC= C S-IP = D-IP = dotq Tag (inside Eth. Hdr) VLN 2 D-MC= Ethernet Header IP Header IP Data S-MC= C S-IP = D-IP = Next, the router accepts the packets from workstation, rewrites the Layer 2 MC addresses and CRC, and forwards the packet to workstation. The switch refers to the routed packet from the RSM as the enabler packet. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v MLS-SE recognizes various matches including CM, details not included. asically, the MLS-SE recognizes that the packet going out of VLN 2 was the same one that came in on VLN. The switch, upon seeing both the candidate and enabler packets, creates an MLS entry in hardware (MLS Cache) such that the switch rewrites and forwards all future packets matching this flow. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v Candidate Packet Info Layer 3 Info S-IP D-IP Layer 2 Info S-MC D-MC C--- MLS- RP Found match in MLS Cache, rewrite Ethernet Header and send directly to Host, forget the router! CEF-ased Multilayer Switches CEF caches routing information in the FI table and Layer 2 next-hop addresses in the adjacency table. Future Packets MLS- SE MLS Cache Dst IP Src IP Port Dst Port Src Port Dst MC TCP Src MC C VLN Interface 2 3/ s future packets from the flow arrive, the MLS-SE uses the destination IP address to look up the entry in the MLS cache. Finding a match, rewrite engine modifies the necessary header information and forwards the frame (the packet is not forwarded to the router). The rewrite operation modifies all the same fields initially modified by the router for the first packet, including the source MC and destination MC addresses. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

14 CEF CEF Routing Table CEF-based MLS forwarding model is used to: Download the control plane information (such as the access lists) to the data plane (on the supervisor, port, or line card) for hardware switching of packets. Control plane represents the Layer 3 engine (route processor) Data plane represents the hardware components such as SICs used by the switch for hardware switching. CEF is a topology-based forwarding model in which all routing information is prepopulated into a forwarding information base (FI). Result is switches can quickly look up routing information such as IP adjacencies and next-hop IP and MC addresses. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v The two main components of CEF are :. FI 2. djacency Table DLS#show ip cef Prefix Next Hop Interface /0 no route /32 receive...0/ FastEthernet0/ /24 attached Vlan /32 receive Vlan /32 receive Vlan /32 receive Vlan /24 attached Vlan /32 receive Vlan /32 receive Vlan /32 receive Vlan / GigabitEthernet0/ / GigabitEthernet0/ /24 attached Vlan /32 receive Vlan /32 receive Vlan /32 receive Vlan /30 attached GigabitEthernet0/ /32 receive GigabitEthernet0/ /32 receive GigabitEthernet0/ for each IP network/subnet in the routing /32 table GigabitEthernet0/ /32 receive GigabitEthernet0/ Ordered with most specific (longest /30 match) first followed attached by less specific FastEthernet0/ subnets /32 receive FastEthernet0/ Mirror image of the forwarding information /32 contained in the IP routing FastEthernet0/ table /32 receive FastEthernet0/ When routing or topology changes /32 occur in the network, receive the IP routing FastEthernet0/ table is updated, and those changes are reflected /30 in the FI GigabitEthernet0/ /4 drop Maintains next-hop address information /24 based on the receive information in the IP routing table /32 receive DLS# 2003, Cisco Systems, Inc. ll rights reserved. CMSN v Forwarding information base Makes IP destination switching decisions. Similar to a routing table: Reformatted into an ordered list with most specific route first 54 CEF CEF-ased MLS Lookups djacency tables Network nodes in the network are said to be adjacent if they can reach each other with a single hop across a link layer. (OSPF, EIGRP) router normally maintains: Routing table containing Layer 3 network and next-hop information RP table containing Layer 3 to Layer 2 address mapping. These tables are kept independently.. Layer 3 packets initiate TCM lookup. 2. The longest match returns adjacency with rewrite information. 3. The packet is rewritten per adjacency information and forwarded. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

15 CEF-ased MLS Operation Packet Rewrite Egress Packet 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v Packet Rewrite Host s MC ddress Packet Rewrite Host s MC ddress L2 Checksum L3 Checksum L2 Checksum L3 Checksum Default Gateway Host TTL Default Host Gateway MC dd Host L3 switch outbound interface TTL - The switch receives another packet: fter a multilayer switch finds valid entries in the FI and adjacency tables, a packet is almost ready to be forwarded. One step remains the packet header information must be rewritten. Multilayer switching occurs as quick table lookups: Find the next-hop address Outbound switch port. The IP header must also be adjusted, as if a traditional router had done the forwarding (TTL). 2003, Cisco Systems, Inc. ll rights reserved. CMSN v The packet rewrite engine makes the following changes to the packet just prior to forwarding: Layer 2 destination address Changed to the next-hop device's MC address Layer 2 source address Changed to the outbound Layer 3 switch interface's MC address Layer 3 IP Time To Live (TTL) Decremented by one, as one router hop has just occurred Layer 2 frame checksum Recalculated to include changes to the Layer 2 and Layer 3 headers Layer 3 IP checksum Recalculated to include changes to the IP header 2003, Cisco Systems, Inc. ll rights reserved. CMSN v

16 Packet Rewrite Host s MC ddress Packet Rewrite Host s MC ddress L2 Checksum L3 Checksum L2 Checksum L3 Checksum Default Host Gateway MC dd Host L3 switch outbound interface TTL - The packet rewrite engine makes the following changes to the packet just prior to forwarding: Layer 2 destination address Changed to the next-hop device's MC address Layer 2 source address Changed to the outbound Layer 3 switch interface's MC address Layer 3 IP Time To Live (TTL) Decremented by one, as one router hop has just occurred Layer 2 frame checksum Recalculated to include changes to the Layer 2 and Layer 3 headers Layer 3 IP checksum Recalculated to include changes to the IP header Default Host Gateway MC dd Host L3 switch outbound interface TTL - traditional router would normally make the same changes to each packet. The multilayer switch must act as if a traditional router were being used, making identical changes. The multilayer switch: Can do this very efficiently with dedicated packet rewrite hardware and with address information obtained from table lookups. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v Packet Rewrite Host s MC ddress CEF L2 Checksum L3 Checksum Default Host Gateway MC dd Host L3 switch outbound interface TTL - The switch performs a Layer 3 lookup and finds a CEF entry for Host. The switch rewrites packets per the adjacency information and forwards the packet to Host on its VLN. 2003, Cisco Systems, Inc. ll rights reserved. 63 CMSN v Catalyst switches do not support routing of all types of frames in hardware. For example, the following list details common frame types that are not supported by hardware switching: Packets with IP header options Packets sourced from or destined to tunnel interfaces Packets using Ethernet encapsulation types other than RP Packets that require fragmentation (exceed MTU of the interface) Two types of CEF Central CEF or ccelerated CEF Forwarding decisions done by SIC that is central to all interfaces. Distributed CEF (dcef) Forwarding decisions done on independently on interfaces or line modules line cards (faster). 2003, Cisco Systems, Inc. ll rights reserved. CMSN v

17 Multilayer Switch Packet Forwarding Process Enabling CEF Some IP packets cannot be processed in hardware. If an IP packet cannot be processed in hardware, it is processed by the Layer 3 engine. The commands required to enable CEF are platform dependent: On the Cisco Catalyst 4000 switch Switch(config-if)#ip cef On the Cisco Catalyst 3550 switch Switch(config-if)#ip route-cache cef 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v Verifying CEF Verify Layer 3 Switching Switch#show ip cef [type mod/port vlan_interface] [detail] Switch# show ip cef vlan detail IP CEF with switching (Table Version ), flags=0x0 0 routes, 0 reresolve, 0 unresolved (0 old, 0 new), peak 0 3 leaves, 2 nodes, 4248 bytes, 4 inserts, invalidations 0 load sharing elements, 0 bytes, 0 references universal per-destination load sharing algorithm, id (0) CEF resets, 0 revisions of existing leaves Resolution Timer: Exponential (currently s, peak s) 0 in-place/0 aborted modifications refcounts: 06 leaf, 052 node Table epoch: 0 (3 entries at this epoch) Switch#show interface {{type mod/port} {port-channel number}} begin L3 Switch#show interface fastethernet 3/3 begin L3 L3 in Switched: ucast: 0 pkt, 0 bytes - mcast: 2 pkt, 778 bytes mcast L3 out Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes packets input, bytes, 0 no buffer Received broadcasts, 2 runts, 0 giants, 0 throttles... Switch# /24, version 6, epoch 0, attached, connected 0 packets, 0 bytes via Vlan, 0 dependencies valid glean adjacency 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v

18 Displaying Hardware Layer 3 Switching Statistics djacency Information Switch#show interfaces {{type mod/port} {port-channel number}} include switched Switch#show adjacency [{{type mod/port} {port-channel number}} detail internal summary] Switch#show interfaces gigabitethernet 9/5 include switched L2 Switched: ucast: 899 pkt, bytes - mcast: 6980 pkt, bytes L3 in Switched: ucast: 3045 pkt, bytes - mcast: 0 pkt, 0 bytes mcast L3 out Switched: ucast: 2975 pkt, 6934 bytes - mcast: 0 pkt, 0 bytes Switch#show adjacency gigabitethernet 9/5 detail Protocol Interface ddress IP GigabitEthernet9/ () 504 packets, 60 bytes 00605C F83F50800 RP 03:49:3 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v Debugging CEF Operations Summary Switch#debug ip cef {drops access-list receive events prefix-ipc table} Displays debug information for CEF Switch#debug ip cef {ipc interface-ipc} Displays debug information related to IPC in CEF Switch#ping ip Performs an extended ping Layer 3 switching is high-performance packet switching in hardware. MLS functionality can be implemented through CEF. CEF uses tables in hardware to forward packets. Specific commands are used to enable and verify CEF operations. Commands to enable CEF are platform dependent. CEF problems can be matched to specific solutions. Specific commands are used to troubleshoot and solve CEF problems. Ordered steps assist in troubleshooting CEF-based problems. 2003, Cisco Systems, Inc. ll rights reserved. CMSN v , Cisco Systems, Inc. ll rights reserved. CMSN v