© 2008 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialBSCI 1 BSCI Module 7 Lesson 2 IGMP and Layer 2 issues IP Multicasting © 2008 Cisco Systems, Inc. All rights reserved.BSCI 2 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Objectives  Explain the operations of IGMPv2 and how IGMPv2 utilizes Join Group and Leave Group messages.  Explain the operations of IGMPv3 and how IGMPv2 and IGMPv3 interoperate.  Describe the methods used to deal with multicast in a Layer 2 switching environment. © 2008 Cisco Systems, Inc. All rights reserved.BSCI 3 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com IGMP Overview © 2008 Cisco Systems, Inc. All rights reserved.BSCI 4 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Internet Group Management Protocol (IGMP) How hosts tell routers about group membership  Routers solicit group membership from directly connected hosts –RFC 1112 specifies IGMPv1 • Supported on Windows 95 –RFC 2236 specifies IGMPv2 •Supported on latest service pack for Windows and most UNIX systems –RFC 3376 specifies IGMPv3 •Supported in Window XP and various UNIX systems © 2008 Cisco Systems, Inc. All rights reserved.BSCI 5 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com IGMPv1  IGMP is a host-to-router protocol used when hosts want to join a multicast group.  With IGMPv1, routers send periodic membership queries to the multicast address 224.0.0.1.  Hosts send membership reports to the group multicast address they want to join.  Hosts silently leave the multicast group.  IGMPv2 is backward compatible with IGMPv1. © 2008 Cisco Systems, Inc. All rights reserved.BSCI 6 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com IGMPv2 RFC 2236  Group-specific query –Router sends query membership message to a single group rather than all hosts (reduces traffic).  Leave group message –Host sends leave message if it leaves the group and is the last member (reduces leave latency in comparison to v1).  Query-interval response time –The Query router sets the maximum Query-Response time (controls burstiness and fine-tunes leave latencies). - how much time they have to respond to a query with a report.  Querier election process –IGMPv2 routers can elect the Query Router without relying on the multicast routing protocol. Highest IP address is Querier © 2008 Cisco Systems, Inc. All rights reserved.BSCI 7 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com IGMPv2—Joining a Group 224.1.1.1 Join Group Join without waiting query msg from router © 2008 Cisco Systems, Inc. All rights reserved.BSCI 8 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com IGMPv2—Leaving a Group IGMPv2 has explicit Leave Group messages, which reduces overall leave latency. © 2008 Cisco Systems, Inc. All rights reserved.BSCI 9 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com IGMPv2—Leaving a Group (Cont.) Hosts H2 and H3 are members of group 224.1.1.1. 1. H2 sends a leave message. © 2008 Cisco Systems, Inc. All rights reserved.BSCI 10 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com IGMPv2—Leaving a Group (Cont.) 2. Router sends group-specific query. [...]... Academy Determining IGMP Version Running Determining which IGMP version is running on an interface rtr-a>show ip igmp interface e0 Ethernet0 is up, line protocol is up Internet address is 1.1.1.1, subnet mask is 25 5 .25 5 .25 5.0 IGMP is enabled on interface Current IGMP version is 2 CGMP is disabled on interface IGMP query interval is 60 seconds IGMP querier timeout is 120 seconds IGMP max query response... CGMP  Effect on switch with Layer 3-aware Hardware/ASICs –Maintain high-throughput performance but cost of switch increases BSCI © 20 08 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 23 CCNP – BSCI Bachkhoa Networking Academy IGMPv3 and IGMP Snooping  Impact of IGMPv3 on IGMP Snooping – IGMPv3 Reports are sent to a separate group (22 4.0.0 .22 ) reduces load on switch CPU... Inbound IGMP access group is not set Multicast routing is enabled on interface Multicast TTL threshold is 0 Multicast designated router (DR) is 1.1.1.1 (this system) IGMP querying router is 1.1.1.1 (this system) Multicast groups joined: 22 4.0.1.40 22 4 .2. 127 .25 4 BSCI © 20 08 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 19 CCNP – BSCI Bachkhoa Networking Academy Layer 2 Multicast... Bách Khoa - www.bkacad.com 22 CCNP – BSCI Bachkhoa Networking Academy IGMP Snooping Solution 2: IGMP snooping  Switches become IGMP- aware  IGMP packets are intercepted by the CPU or by special hardware ASICs  Switch examines contents of IGMP messages to learn which ports want what traffic  Effect on switch without Layer 3-aware Hardware/ASICs –Must process all Layer 2 multicast packets –Administration... is the primary purpose of IGMP? 2 When 2 IGMP routers are located on the same Ethernet segment, which router will be the designated querier? 3 What does the ICMPv2 Query router doe when it receives a Leave Message? BSCI © 20 08 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 17 CCNP – BSCI Bachkhoa Networking Academy IGMP Layer 2 Issues BSCI © 20 08 Cisco Systems, Inc All... IGMPv2—Leaving a Group (Cont.) BSCI © 20 08 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 13 CCNP – BSCI Bachkhoa Networking Academy IGMPv3—Joining a Group Joining member sends IGMPv3 report to 22 4.0.0 .22 immediately upon joining BSCI © 20 08 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 14 CCNP – BSCI Bachkhoa Networking Academy IGMPv3—Joining... www.bkacad.com 20 CCNP – BSCI Bachkhoa Networking Academy Layer 2 Multicast Switching Solutions  Cisco Group Management Protocol (CGMP): Simple, proprietary; routers and switches  IGMP snooping: Complex, standardized, proprietary implementations; switches only BSCI © 20 08 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 21 CCNP – BSCI Bachkhoa Networking Academy Layer 2 Multicast... No Report Suppression in IGMPv3  IGMP Snooping should not cause a serious performance problem once IGMPv3 is implemented BSCI © 20 08 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 24 CCNP – BSCI Bachkhoa Networking Academy Self Check 1 What command is used to determine the version of IGMP active on an interface? 2 How does a typical layer 2 switch treat multicast traffic?... article –http://en.wikipedia.org/wiki /IGMP  Multicast in a Campus Network: CGMP and IGMP Snooping –http://www.cisco.com/warp/public/473 /22 .html  IP Multicast Glossary of Terms –http://www.cisco.com/en/US/tech/tk 828 /tech_brief0900aecd80 1bca26.html BSCI © 20 08 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 28 CCNP – BSCI BSCI © 20 08 Cisco Systems, Inc All rights reserved... What type of switch is recommending for use with IGMP snooping? BSCI © 20 08 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 25 CCNP – BSCI Bachkhoa Networking Academy Summary  IGMPv2 is a protocol used by multicast clients to join a multicast group  IGMPv3 allows a receiver to specify a source  If controls such as CGMP and IGMP snooping are not added at the Ethernet switching . www.bkacad.com Objectives  Explain the operations of IGMPv2 and how IGMPv2 utilizes Join Group and Leave Group messages.  Explain the operations of IGMPv3 and how IGMPv2 and IGMPv3 interoperate.  Describe the. © 20 08 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialBSCI 1 BSCI Module 7 Lesson 2 IGMP and Layer 2 issues IP Multicasting © 20 08 Cisco Systems, Inc. All rights reserved.BSCI 2 CCNP. groups joined: 22 4.0.1.40 22 4 .2. 127 .25 4 © 20 08 Cisco Systems, Inc. All rights reserved.BSCI 20 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Layer 2 Multicast