My knowledge of Cisco is basic at best but having spent a few days configuring one I decided to write down some aspects, more for future reference than anything else.

Configuring the interfaces

The Cisco I was working on had several physical FastEthernet ports. The first 2 where used and I was supposed to configure the 3’rd: FastEthernet2. Setting an IP to the FastEthernet2 cannot be done directly but instead it is done by creating a Vlan. Since a Vlan was already created for FastEthernet1 my first mistake was to suppose it is enough to just create a Vlan 2 which would configure the FastEthernet2. But the truth, and this is something I did not though about was that by default all the FastEthernet2 belong to the default and had the same IP as FastEthernet1.

# show vlan-switch <br></br>VLAN Name                             Status    Ports<br></br>---- -------------------------------- --------- -------------------------------<br></br>1    default                          active    Fa1, Fa2, Fa3, Fa4

So after creating the Vlan 2 this had to be added to the Vlan database and associated to the FastEthernet2

# vlan database<br></br>(vlan)# vlan 2 name vlan2<br></br>(vlan)# exit<br></br># conf t<br></br>(config)#int FastEthernet2<br></br>(config-if)#switchport access vlan 2<br></br>(config-if)#end<br></br># show vlan-switch<br></br>LAN Name                             Status    Ports<br></br>---- -------------------------------- --------- -------------------------------<br></br>1    default                          active    Fa1, Fa3, Fa4<br></br>2    Vlan2                            active    Fa2<br></br>

Only now did the FastEthernet2 had the required address.

Remote logging

It is possible to log to a remote syslog server. For this the remote server must run with the -r switch. In order to enable logging for all message levels to a remote server the following configuration is required:

(config)#logging trap debugging     #max level to log<br></br>(config)#logging facility local7    #logging facility<br></br>(config)#logging 10.10.9.5          #remote server

At this point you can enable some debug options such as debug ip igmp or something else according to your need.

Multicast

The first thing in order to enable multicast routing is to enable it

ip multicast-routing

Then configure the interfaces accordingly:

! this is the source<br></br>interface Tunnel1<br></br> ip pim sparse-mode<br></br> no ip route-cache cef<br></br> no ip route-cache<br></br> no ip mroute-cache<br></br><br></br>! will route on Vlan2<br></br>interface Vlan2<br></br> ip pim neighbor-filter ACLA<br></br> ip pim sparse-mode<br></br> ip igmp access-group ACLB<br></br><br></br>! not so sure what this is good for but as I understand it is good <br></br>! since I only want to route in a local lan and no more<br></br>ip access-list standard ACLA<br></br> deny   any<br></br><br></br>! this will control what groups clients in the Vlan 2 network will be<br></br>! allowed to join<br></br>ip access-list standard ACLB<br></br> permit 224.0.1.40<br></br>! all your groups here<br></br> permit 224.0.2.0 0.0.0.255<br></br> deny   any<br></br>!<br></br>! this will show your mrouting configuration<br></br>! you can debug mroute with debug ip mpackets or debug ip igmp or debug ip pim<br></br>sh ip mroute     <br></br>IP Multicast Routing Table<br></br>Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,<br></br>       L - Local, P - Pruned, R - RP-bit set, F - Register flag,<br></br>       T - SPT-bit set, J - Join SPT, M - MSDP created entry,<br></br>       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,<br></br>       U - URD, I - Received Source Specific Host Report, Z - Multicast Tunnel<br></br>       Y - Joined MDT-data group, y - Sending to MDT-data group<br></br>Outgoing interface flags: H - Hardware switched, A - Assert winner<br></br> Timers: Uptime/Expires<br></br> Interface state: Interface, Next-Hop or VCD, State/Mode<br></br><br></br>(*, 224.0.1.40), 1w1d/00:02:42, RP, flags: SJCL<br></br>  Incoming interface: Tunnel1, RPF nbr<br></br>  Outgoing interface list:<br></br>    Vlan2, Forward/Sparse, 1d12h/00:02:42<br></br>

Once a client has joined a group it will be able to receive messages if the group is in the ACLB igmp access-list.
It is also possible to configure a

 ip static igmp-group

for an interface in which case the messages will be sent no mater if an application has joined or not. This guide is very helpful for multicast problems.