CCNA Lab - Solution Rev1.0 Multicast I

Multicast Groups and IGMP Task 6.1: Configure on all routers: PE3-RACK1config#ip multicast-routing PE3-RACK1#show ip multicast Multicast Routing: enabled Multicast Multipath: disabled

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Before you begin, make sure you have Unicast routing connectivity between CE1, CE2, CE8, PE1, PE2, and PE3 Otherwise, you will get RPF checks failures and Multicast won’t work One of the

workarounds is to use ip mroute static statements RPF is checked

against them before using Unicast IP routing table

Multicast Groups and IGMP Task 6.1:

Configure on all routers:

PE3-RACK1(config)#ip multicast-routing

PE3-RACK1#show ip multicast Multicast Routing: enabled Multicast Multipath: disabled Multicast Route limit: No limit Multicast Triggered RPF check: enabled Multicast Fallback group mode: Dense

Task 6.2:

CE8-RACK1(config)#int FastEthernet0/1 CE8-RACK1(config-if)#ip igmp join-group 224.8.8.8 CE8-RACK1(config-if)#ip igmp join-group 225.8.8.8 CE8-RACK1(config-if)#ip igmp join-group 235.235.235.235 CE8-RACK1(config-if)#ip igmp join-group 229.0.0.1 CE8-RACK1(config-if)#ip igmp join-group 229.0.0.2

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CE8-RACK1#show ip igmp groups IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter 235.235.235.235 FastEthernet1/0 00:00:25 stopped 192.168.100.8 224.8.8.8 FastEthernet1/0 00:00:25 stopped 192.168.100.8 225.8.8.8 FastEthernet1/0 00:00:25 stopped 192.168.100.8 229.0.0.1 FastEthernet1/0 00:00:25 stopped 192.168.100.8 229.0.0.2 FastEthernet1/0 00:00:25 stopped 192.168.100.8

The IGMP join-group command makes a router advertise Multicast

groups to itself Now, CE8 wants to receive Multicast traffic on the specified Multicast group addresses

Task 6.3:

CE2-RACK1(config)#int ethernet0/0 CE2-RACK1(config-if)#ip igmp join-group 224.2.2.2 CE2-RACK1(config-if)#ip igmp join-group 225.2.2.2 CE2-RACK1(config-if)#ip igmp join-group 235.235.235.235

CE2-RACK1#show ip igmp groups IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter 235.235.235.235 Ethernet0/0 00:00:17 never 10.23.1.1 224.2.2.2 Ethernet0/0 00:00:28 never 10.23.1.1 225.2.2.2 Ethernet0/0 00:00:23 never 10.23.1.1

Task 6.4:

CE1-RACK1(config)#int ethernet0/0 CE1-RACK1(config-if)#ip igmp join-group 224.1.1.1 CE1-RACK1(config-if)#ip igmp join-group 225.1.1.1 CE1-RACK1(config-if)#ip igmp join-group 235.235.235.235

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CE1-RACK1#sh ip igmp groups IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter 225.1.1.1 Ethernet0/0 00:01:30 stopped 10.13.1.1 224.1.1.1 Ethernet0/0 00:01:35 stopped 10.13.1.1 235.235.235.235 Ethernet0/0 00:01:24 stopped 10.13.1.1

Task 6.5:

So far you don’t have ip pim enabled anywhere To get this task

done, you need to turn on Multicast routing protocol on these two interfaces: PE3 E0/0.23 and CE2 E0/0 IGMPv2 election process on one Ethernet segment happens by default when there’s more than one interface with Multicast routing protocol enabled This process will elect the IGMP querying router for the segment IGMP router with the lowest IP address will be elected

Before enabling IP PIM on these two interfaces, here’s an output of

the show ip igmp int e0/0 command on CE2:

CE2-RACK1#sh ip igmp int e0/0 Ethernet0/0 is up, line protocol is up Internet address is 10.23.1.1/24 IGMP is enabled on interface Current IGMP host version is 2 Current IGMP router version is 2 IGMP query interval is 60 seconds IGMP querier timeout is 120 seconds IGMP max query response time is 10 seconds Last member query count is 2

Last member query response interval is 1000 ms Inbound IGMP access group is not set

IGMP activity: 3 joins, 0 leaves Multicast routing is disabled on interface Multicast TTL threshold is 0

Multicast groups joined (number of users):

224.2.2.2(1) 225.2.2.2(1) 235.235.235.235(1)

Notice that IGMPv2 is enabled on the Ethernet0/0 interface but Multicast routing is not These conditions won’t allow IGMPv2 election process to start on this Ethernet segment Also, notice that CE2 and PE3 right now only act as IGMP hosts, but not as IGMP routers If you look at IGMP groups on PE3, you won’t see CE2’s groups:

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PE3-RACK1#sh ip igmp groups IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter

Configure one of the IP PIM modes on both routers Start with PE3:

PE3-RACK1(config)#int ethernet0/0.23 PE3-RACK1(config-if)#ip pim sparse-dense-mode

As soon as you enable Multicast routing protocol on PE3 Ethernet0/0.23, PE3 will send out IGMPv2 report query on the segment and then accept IGMP joins from CE2 Ethernet0/0 interface and add the groups to its IGMP group table:

PE3-RACK1#sh ip igmp groups IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter 235.235.235.235 Ethernet0/0.23 00:00:12 00:02:47 10.23.1.1 224.2.2.2 Ethernet0/0.23 00:00:11 00:02:48 10.23.1.1 225.2.2.2 Ethernet0/0.23 00:00:12 00:02:47 10.23.1.1 224.0.1.40 Ethernet0/0.23 00:00:14 00:02:45 10.23.1.3

Notice the new 224.0.1.40 group that PE3 has joined on Ethernet0/0.23 interface It enables these routers to receive PIM Sparse Mode Auto-RP discovery messages sent to the 224.0.1.40 group address Auto-RP will be configured later on

Now, let’s enable IP PIM on CE2:

CE2-RACK1(config)#int ethernet0/0 CE2-RACK1(config-if)#ip pim sparse-dense-mode

Go back to PE3:

PE3-RACK1#sh ip igmp interface ethernet0/0.23 Ethernet0/0.23 is up, line protocol is up Internet address is 10.23.1.3/24

IGMP is enabled on interface Current IGMP host version is 2 Current IGMP router version is 2 IGMP query interval is 60 seconds IGMP querier timeout is 120 seconds IGMP max query response time is 10 seconds Last member query count is 2

IGMP activity: 4 joins, 0 leaves Multicast routing is enabled on interface

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Multicast TTL threshold is 0 Multicast designated router (DR) is 10.23.1.3 (this system) IGMP querying router is 10.23.1.1

Multicast groups joined (number of users):

224.0.1.40(1)

Pay attention to the two highlighted lines in the output

The first highlighted line shows PIM Designated Router on this segment, which is PE3 Multicast routers automatically elect a PIM designated router for the LAN (subnet) This is the router with the highest IP address The designated router is responsible for

sending IGMP host-query messages to all hosts on the LAN In zsparse mode, the designated router also sends PIM register and PIM join messages toward the RP router

The second highlighted line shows IGMP elected querying router on this segment, which is CE2 This is the router with the lowest IP address IGMPv2 Election process took place Let’s double check CE2:

CE2-RACK1#sh ip igmp int e0/0 Ethernet0/0 is up, line protocol is up Internet address is 10.23.1.1/24 IGMP is enabled on interface Current IGMP host version is 2 Current IGMP router version is 2 IGMP query interval is 60 seconds IGMP querier timeout is 120 seconds IGMP max query response time is 10 seconds Last member query count is 2

IGMP activity: 5 joins, 1 leaves Multicast routing is enabled on interface Multicast TTL threshold is 0

Multicast designated router (DR) is 10.23.1.3 IGMP querying router is 10.23.1.1 (this system) Multicast groups joined (number of users):

224.2.2.2(1) 225.2.2.2(1) 235.235.235.235(1) 224.0.1.40(1)

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Task 6.6:

Enable this requirement by configuring IGMP static-group This

command acts almost like IGMP join-group, but the interface doesn’t actually join the group If you were to ping the Multicast

address that was configured in the IGMP join-group command,

you would get an ICMP response from the interface If you were to

ping the Multicast address that was configured in IGMP

static-group command, you would not get an ICMP response from the

interface You would only get ICMP responses from the receivers on the segment, if any

CE8-RACK1(config)#int FastEthernet0/1 CE8-RACK1(config-if)#ip igmp static-group 235.5.5.5

CE8-RACK1#sh ip igmp groups IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter 235.235.235.235 FastEthernet0/1 01:03:19 stopped 192.168.100.8 224.8.8.8 FastEthernet0/1 01:03:19 stopped 192.168.100.8 225.8.8.8 FastEthernet0/1 01:03:19 stopped 192.168.100.8 229.0.0.1 FastEthernet0/1 01:03:19 stopped 192.168.100.8 229.0.0.2 FastEthernet0/1 01:03:19 stopped 192.168.100.8

Notice, that 235.5.5.5 has not yet appeared in the IGMP group list The reason is lack of Multicast routing protocol on FastEthernet0/1 interface Let’s enable IP PIM on this interface

CE8-RACK1(config)#int FastEthernet0/1 CE8-RACK1(config-if)#ip pim sparse-dense-mode

CE8-RACK1#sh ip igmp groups IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter 235.235.235.235 FastEthernet0/1 01:05:03 00:02:48 192.168.100.1 235.5.5.5 FastEthernet0/1 00:00:13 stopped 0.0.0.0 224.8.8.8 FastEthernet0/1 01:05:03 00:02:47 192.168.100.1 225.8.8.8 FastEthernet0/1 01:05:03 00:02:47 192.168.100.1 229.0.0.1 FastEthernet0/1 01:05:03 00:02:48 192.168.100.1 229.0.0.2 FastEthernet0/1 01:05:03 00:02:48 192.168.100.1 224.0.1.40 FastEthernet0/1 00:00:13 00:02:46 192.168.100.1

235.5.5.5 now appears in the table It has no reporters because CE8 is not acting as an IGMP host, it only creates IGMP group for Multicast routing

Task 6.7:

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You are asked to send out IGMPv2 Report Query every 30 seconds

CE8-RACK1(config)#int FastEthernet0/1 CE8-RACK1(config-if)#ip igmp query-interval 30

CE8-RACK1#sh ip igmp int FastEthernet0/1 FastEthernet0/1 is up, line protocol is up Internet address is 192.168.100.8/24 IGMP is enabled on interface

Current IGMP host version is 2 Current IGMP router version is 2 IGMP query interval is 30 seconds IGMP querier timeout is 60 seconds IGMP max query response time is 10 seconds Last member query count is 2

IGMP activity: 9 joins, 2 leaves Multicast routing is enabled on interface Multicast TTL threshold is 0

224.8.8.8(1) 225.8.8.8(1) 235.235.235.235(1) 229.0.0.1(1) 229.0.0.2(1) 224.0.1.40(1)

Task 6.8:

To make CE8 compatible with this topology, you need to force Fa0/1 into the IGMP version 1 mode

CE8-RACK1(config)#int FastEthernet0/1 CE8-RACK1(config-if)#ip igmp version 1

CE8-RACK1#sh ip igmp int FastEthernet0/1 FastEthernet0/1 is up, line protocol is up Internet address is 192.168.100.8/24 IGMP is enabled on interface

Current IGMP host version is 1 Current IGMP router version is 1 IGMP query interval is 30 seconds Inbound IGMP access group is not set IGMP activity: 9 joins, 2 leaves Multicast routing is enabled on interface Multicast TTL threshold is 0

224.8.8.8(1) 225.8.8.8(1) 235.235.235.235(1) 229.0.0.1(1) 229.0.0.2(1) 224.0.1.40(1)

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Task 6.9:

3750(config)#ip igmp snooping vlan 23 immediate-leave

Task 6.10:

This is a trick question Such change cannot be made on a 3750 It

has to be done on PE3 If you issue sh ip igmp snooping vlan 23

on 3750, it will say "IGMP_ONLY."

PE3(config)#int Ethernet0/0.23 PE3(config-if)#ip cgmp

Now, if you issue sh ip igmp snooping vlan 23 on the 3750, it

will say "IGMP_CGMP"

Task 6.11:

CE8-RACK1(config)#int FastEthernet0/1 CE8-RACK1(config-if)#ip sdr listen

CE8-RACK1#sh ip sdr SDR Cache - 0 entries

Task 6.12:

You have to configure ip pim sparse-dense-mode on all

interfaces If there is no RP (Rendezvous Point) available for a group, the interface will operate in dense mode for that group If there’s an RP available (Auto-RP, BSR, or static) for a group, the interface will operate in Sparse mode for that group Some interfaces already have IP PIM sparse-dense-mode enabled Let’s enable it on the rest of the routers and interfaces

CE8-RACK1(config)#int fastethernet0/0 CE8-RACK1(config-if)#ip pim sparse-dense-mode

PE1-RACK1(config)#int fastethernet0/0 PE1-RACK1(config-if)#ip pim sparse-dense-mode PE1-RACK1(config)#int fastethernet0/1

PE1-RACK1(config-if)#ip pim sparse-dense-mode

PE2-RACK1(config)#int ethernet0/0.82 PE2-RACK1(config-if)#ip pim sparse-dense-mode PE2-RACK1(config)#int ethernet0/0.123

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PE2-RACK1(config-if)#ip pim sparse-dense-mode PE2-RACK1(config)#int ethernet0/0.21

PE3-RACK1(config)#int ethernet0/0.23 PE3-RACK1(config-if)#ip pim sparse-dense-mode PE3-RACK1(config)#int ethernet0/0.123

Let’s check PIM status on one of the routers

PE2-RACK1#sh ip pim neighbor PIM Neighbor Table

Neighbor Interface Uptime/Expires Ver DR Address Priority/Mode

172.16.123.3 Ethernet0/0.123 00:01:43/00:01:30 v2 1 / DR P 10.82.1.1 Ethernet0/0.82 00:04:21/00:01:19 v2 1 / P 172.16.12.1 Ethernet0/0.21 00:02:50/00:01:22 v2 1 / P

The above output shows IP addresses of the PIM neighbors

PE2-RACK1#sh ip pim interface Address Interface Ver/ Nbr Query DR DR Mode Count Intvl Prior 172.16.123.2 Ethernet0/0.123 v2/SD 1 30 1 172.16.123.3 10.82.1.2 Ethernet0/0.82 v2/SD 1 30 1 10.82.1.2 172.16.12.2 Ethernet0/0.21 v2/SD 1 30 1 172.16.12.2

The above output shows IP addresses of the local interfaces on the router running PIM You can also see that PIM already went

through the PIM Designated Router election process The router with the highest IP address on the segment has won Also notice that PIM Version 2 is being used and that interfaces are in Sparse Dense (SD) mode

Let’s look at the Multicast routing table on PE2

PE2-RACK1#sh ip mroute

IP Multicast Routing Table Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,

L - Local, P - Pruned, R - RP-bit set, F - Register flag,

T - SPT-bit set, J - Join SPT, M - MSDP created entry,

X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,

U - URD, I - Received Source Specific Host Report, Z - Multicast Tunnel,

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Y - Joined MDT-data group, y - Sending to MDT-data group

V - RD & Vector, v - Vector Outgoing interface flags: H - Hardware switched, A - Assert winner Timers: Uptime/Expires

Interface state: Interface, Next-Hop or VCD, State/Mode (*, 224.0.1.40), 00:08:36/00:02:16, RP 0.0.0.0, flags: DCL Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list:

Ethernet0/0.123, Forward/Sparse-Dense, 00:06:48/00:00:00 Ethernet0/0.82, Forward/Sparse-Dense, 00:08:20/00:00:00 Ethernet0/0.21, Forward/Sparse-Dense, 00:08:36/00:00:00

Notice that multicast routing table is empty (except for the 224.0.1.40 Auto-RP discovery group) None of the configured IGMP groups are in the table This is because all of our interfaces and groups are currently operating in Dense Mode, and not Sparse Mode The reason why we are operating in Dense Mode is because there’s no Auto-RP and no static RPs configured Dense Mode uses the Flood technique In the beginning, the topology doesn’t have routing for Multicast groups As soon as the first Multicast packet

is sent from a source to the group, it will be flooded to all routers in the PIM Dense topology, and the Multicast routing table will show the (S,G) entries for each source We are going to try this in a little while

If you look at the Multicast routing table on the routers that have IGMP groups configured, it will show you the (*,G) entries for each Multicast group The flag is DCL, Dense, Connected, Local

CE8-RACK1#sh ip mroute

Interface state: Interface, Next-Hop or VCD, State/Mode (*, 235.235.235.235), 01:12:19/00:02:53, RP 0.0.0.0, flags: DCL Incoming interface: Null, RPF nbr 0.0.0.0

FastEthernet0/0, Forward/Sparse-Dense, 00:16:26/00:00:00 FastEthernet0/1, Forward/Sparse-Dense, 01:12:19/00:00:00 (*, 235.5.5.5), 01:12:20/stopped, RP 0.0.0.0, flags: DC Incoming interface: Null, RPF nbr 0.0.0.0

FastEthernet0/0, Forward/Sparse-Dense, 00:16:26/00:00:00 FastEthernet0/1, Forward/Sparse-Dense, 01:12:20/00:00:00

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(*, 239.255.255.255), 00:25:25/00:02:53, RP 0.0.0.0, flags: DCL Incoming interface: Null, RPF nbr 0.0.0.0

FastEthernet0/0, Forward/Sparse-Dense, 00:16:26/00:00:00 FastEthernet0/1, Forward/Sparse-Dense, 00:25:25/00:00:00 (*, 224.2.127.254), 00:25:26/00:02:52, RP 0.0.0.0, flags: DCL Incoming interface: Null, RPF nbr 0.0.0.0

FastEthernet0/0, Forward/Sparse-Dense, 00:16:28/00:00:00 FastEthernet0/1, Forward/Sparse-Dense, 01:12:22/00:00:00

Notice that our static group 235.5.5.5 is Connected, but not Local Connected groups are groups discovered by IGMP and will also

show up in the show ip igmp groups Local groups are groups that have router’s interface as one of the receivers The join-

group command creates this condition, but the static-group does

not

Task 6.13:

CE8-RACK1(config)#int fastethernet0/0 CE8-RACK1(config-if)#ip pim query-interval 20 PE2-RACK1(config)#int ethernet0/0.82

PE2-RACK1(config-if)#ip pim query-interval 20

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PE2-RACK1#sh ip pim interface Address Interface Ver/ Nbr Query DR DR Mode Count Intvl Prior 172.16.123.2 Ethernet0/0.123 v2/SD 1 30 1 172.16.123.3 10.82.1.2 Ethernet0/0.82 v2/SD 1 20 1 10.82.1.2 172.16.12.2 Ethernet0/0.21 v2/SD 1 30 1 172.16.12.2

6.14:

CE2-RACK1#ping 224.8.8.8 Type escape sequence to abort

Sending 1, 100-byte ICMP Echos to 224.8.8.8, timeout is 2 seconds:

Reply to request 0 from 10.82.1.1, 60 ms

CE1-RACK1#ping 224.8.8.8 Type escape sequence to abort

Sending 1, 100-byte ICMP Echos to 224.8.8.8, timeout is 2 seconds:

Reply to request 0 from 10.82.1.1, 52 ms

The ping was successful Now let’s look at the Multicast routing table on CE2 CE2 participates in PIM, so we should see PIM Dense tree for the 224.8.8.8 group

CE2-RACK1#sh ip mroute 224.8.8.8 Group 224.8.8.8 not found

The reason why you don’t see any (S,G) Dense entries in the Multicast routing table on CE2 is because CE2 acts only as a source when sending traffic to the 224.8.8.8 group CE2 doesn’t need to have Multicast routing table entries for this group When you ping 224.8.8.8, IOS® simply makes an ICMP packet for each interface running IP PIM routing protocol and sends it out Now let’s look at the Multicast routing table on directly connected PE3 router

PE3-RACK1#sh ip mroute 224.8.8.8

Interface state: Interface, Next-Hop or VCD, State/Mode

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