Multicast Lab Tips

  • On each device do a show ip pim interface and show ip pim neighbour , highlight the multicast links and note down the DR and the mode e.g. SD, S or D (Dense). Also enable ip multicast-routing on all participating devices.
  • Use BSR instead of Autorp if you can as BSR allows you to filter multicast with the ip pim bsr-border command easily at the edge routers, it is tricky to so this in autorp. Also no need for ip pim autorp listener on each router when using autorp (alternatively you can put it into sparse-dense mode if the listener command is restricted on the lab – needed for Sparse mode though).
  • Use ip pim nbma-mode to effectively disable split horizon. Alternatively use a GRE tunnel between the spokes if that command is not an option or if it dense mode running across a NBMA network as dense mode can not bypass split horizon rules.
  • Set the ip pim dr-priority to 0 on all spokes and a high value, say 255, on the hub.
  • Anything to do with multicast can typically be found under ip pim, ip multicast and ip igmp. e.g. ip multicast boundary under the interface (alternative to using scope).
  • If mapping agent is required to associate a particular group to an RP, you will need to use rp-announce-filter which references access-lists that contains both the RP address rp-list and the groups group-list. You will also have to use the exact same group-list on the RP itself after the send-rp-announce command so that the RP can volunteer for those groups.
  • Deny statements do not work in a RP group-list / access-list. as it treats a deny as flooding in dense mode
  • To deny a PIM neighbourship form forming, use ip pim neighbor-filter # under the interface.
  • ip pim spt-threshold is to be used if you need to deny changing to shortest path source tree. RP is a shared tree where devices sends registers and join requests too. Once everyone figures out the stream, they will bypass the RP and use shortest path tree (S,G). Set spt-threshold to infinity so that devices always uses the RP and not their own shortest path. Do show ip mroute and look at the flags to verify (J in flags means shortest path).
  • Use ip igmp static-group instead of join-group if an application is unable to use IGMP to respond to a group or it needs to be fast switched. Verify this with show ip igmp membership=
  • Can filter / restrict specific multicast group under the interface using ip igmp access-group 1
  • is the mapping agent and is the auto-rp

OSPF Lab Tips

  • When peering between a router and a switch, use ip/ipv6 ospf mtu-ignore under the interface otherwise adjacency may be stuck in the exstart state.
  • Good practice is to manually set the router ID e.g. for R1.
  • Make the frame-relay hub the ip ospf priority 255 and the spokes ip ospf priority 0
  • Use neighbour statements on the HUB or point-to-multicast network type when dealing with OSPF over Frame-Relay. The latter will show the hub as the next-hop where as neighbour statements won’t.
  • Virtual-Links will be treated as area 0 so do not forget authentication for area 0 etc for the virtual links.
  • auto-cost reference-bandwidth is the command to use to change globally how OSPF allocate cost to various interface speed e.g. 10Mbps, 100 Mbps etc. Usually Auto-cost Reference-bandwidth / Interface bandwidth will EQUAL OSPF Cost This can be verified with show ip ospft interface and look at cost to see if it has been changed. This will need to be done on EVERY OSPF ROUTER.
  • Anything really to do with LSA can been seen with show ip ospf and configured at the router-process with timers lsa arrival and timers pacing
  • Use domain-id to connect two different OSPF processes to appear at inter-area routes rather than external routes.

IPV6 Routing Protocols Lab Tips


  • You must specify the RID in the Router Process as a IPV4 format (x.x.x.x).
  • You must do a no shutdown under the routing process.
  • Can enable under the interface as ipv6 eigrp [as no.]


  • Neighbour statement done under the interface.
  • Authentication is done using IPSEC and not MD5

IPV6 – Decimal and Hex conversions Lab Tips

* To convert a decimal (IPV4) into a Hex (IPV6)


1 – – 168 / 16 = 10.5 we are only interested in everything before the decimal point which is 10. 10 in hex is A.

2 — 10.5 -/minus 10 (everything before decimal point) = 0.5

3 — 0.5 x 16 = 8

4 — 168 in hex is A8

* To covert Hex (IPV6)  into Decimal (IPV4)

e.g. A8

1 — A8 split up on it’s own is 10 and 8

2 — 10 in binary is 1010

3 — 8 in binary is 0100

4 — combine them both 1010 0100

5 – – 128+0+32+0+0+8+0+0 = 168

6 — A8 in decimal is 168

IPV6 – Multicast Lab Tips

  • Enable this using ipv6 cef, ipv6 unicast-routing and ipv6 multicast routing.
  • The above latter command will enable PIM Sparse-mode on all ipv6 interfaces! Unlike ipv4 you had to do the ip pim sparse-mode on each interface.
  • To join a multicast group use ipv6 mld join-group which is the same as ip igmp join-group.
  • Auto-rp no longer exists. only static and BSR. Same commands used as in IPV4.
  • Configuring the RP will create a GRE tunnel! in ipv4 the router sends a join request to the RP by encapsulating it in a unicast. in IPV6 a GRE tunnel is created instead.

IPV6 – Network Setup Lab Tips

  • Always do IPV6 unicast-routing to enable IPV6 on router and switches.
  • Switches require sdm prefer dual-ipv4-and-ipv6 default to enable IPV6 (will require a reboot)
  • Always hard code the interface link-local address e.g. FE80::1 link-local as most routing protocols uses the link local address when forming adjacencies (ospf) and / or sourcing updates. Assign the same link-local address on all the IPV6 interfaces of that router as it will make life easier e.g. FE80::1 link-local on all IPV6 interfaces of R1, including tunnel interfaces
  • Exception to the above is when configuring eui-64 address, do not hard code the link-local as the dynamic address will not be created.
  • Make sure link local addresses are mapped in the Frame Relay statements as it will break OSPFV3 across frame-relay.
  • Frame-relay broadcast statement only need to be used once per DLCI, so no need to use it for both the link-local and global address map statements.
  • IPV6 does not use Arp, it uses Neighbour Discovery which relies on ICMP. If you see nothing under show iv6 neighbour then ping the destination router and you should see that show command populate. This is basically equivalent to a show ip arp
  • Site Local address starts with FEC0