Cisco Certification: An Introduction To Multilayer Switching And SVIs |
|
By: Chris Bryant Posted: 2007-08-01 10:35:02 |
| Sure, you have to know all about SVIs and multilayer switching to earn your CCNP, but you also need to know about them because they're so commonplace in today's networks!Why? We can use an SVI to allow inter-VLAN communication on a multilayer switch, eliminating the need for a separate router to get involved.In this example, we have Host_1 in VLAN 11 and Host_3 in VLAN 33. Before we begin configuring, we'll send pings between the two hosts. (We'll use Cisco routers for the hosts in this lab, which is why the ping output may look familiar!)HOST_1#ping 30.1.1.1Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds:.....Success rate is 0 percent (0/5)HOST_3#ping 20.1.1.1Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 20.1.1.1, timeout is 2 seconds:.....Success rate is 0 percent (0/5)As we expect, there's no IP connectivity between the hosts. Assuming the appropriate switch ports are already placed in VLAN 11 and VLAN 33, we'll now create two switched virtual interfaces on this multilayer switch. One will represent VLAN 33, and the other will represent VLAN 11.SW1(config)#int vlan1101:30:04: %LINK-3-UPDOWN: Interface Vlan11, changed state to up01:30:05: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan11, changed state to upSW1(config-if)#ip address 20.1.1.11 255.255.255.0SW1(config-if)#int vlan3301:30:11: %LINK-3-UPDOWN: Interface Vlan33, changed state to up01:30:12: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan33, changed state to upSW1(config-if)#ip address 30.1.1.11 255.255.255.0At this point, we've still got a problem when we look at the routing table.SW1# show ip routeDefault gateway is not setHost Gateway Last Use Total Uses InterfaceICMP redirect cache is emptyThe problem is that we don't have a routing table, because IP routing is off by default on a multilayer switch. Let's turn IP routing on and then check the routing table.SW1(config)#ip routingSW1(config)#^ZSW1#show ip routeGateway of last resort is not set20.0.0.0/24 is subnetted, 1 subnetsC 20.1.1.0 is directly connected, Vlan1130.0.0.0/24 is subnetted, 1 subnetsC 30.1.1.0 is directly connected, Vlan33Now we're in good shape! The hosts need to have their default gateway set to the appropriate SVI IP address; here, Host_1 should have its gateway set to 20.1.1.11, and Host_3 to 30.1.1.11. After doing so, inter-VLAN communication is now in place, as shown by the ping output below.HOST_1#ping 30.1.1.1Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds: !!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 msHOST_3#ping 20.1.1.1Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 20.1.1.1, timeout is 2 seconds: !!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 msIn a future Cisco certification tutorial, we'll take a look at configuring a multilayer switch port as a routed port, and assign an IP address to that port. See you then!Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free Cisco CCNP Certification and CCNA Certification Exam tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages.You can also visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and daily CCNA / CCNP exam questions! Details are on the website.For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", just visit the website! You can also get FREE CCNA and CCNP exam questions every day!Take the exclusive CCNA Mastermind Boot Camp with The Bryant Advantage! |
| Trackback url: https://article.abc-directory.com/article/2807 |