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Multicast of the 7750 – IGMP static joins
Here we will configure IGMP and associate an interface with it. We will also create a static join which is useful for troubleshooting but I guess on a platform like the 7750 you would use it for broadcast TV.
Let’s create an interface first, I’ll call it igmp but the name is irrelevant to the IGMP process.
config router interface igmp
address 3.3.3.3/24
port 1/1/2:3
Now lets start IGMP and associate the interface with the process
config router igmp interface "igmp"
Unshut the process if not already done
So now the interface is there we need to associate the static mapping to it. We wil use group 239.3.3.3. Once we do this we will see a warning message
*A:R3>config>router>igmp>if# static group 239.3.3.3
WARNING: CLI The static group is not yet created because source or starg is not yet specified.
What this means is we need to either set the static source or configure it as ASM, the starg keyword meaning (*,g)
so all we need to do is lash in the keyword and we should see the shared tree back to the RP
starg
And we do, the link to R3 is in the OIL
*A:R4# show router pim group 239.3.3.3 detail
.
===============================================================================
PIM Source Group ipv4
===============================================================================
Group Address : 239.3.3.3
Source Address : *
RP Address : 44.44.44.44
Advt Router : 44.44.44.44
Flags : Type : (*,G)
MRIB Next Hop :
MRIB Src Flags : self Keepalive Timer : Not Running
Up Time : 0d 00:09:51 Resolved By : rtable-u
.
Up JP State : Joined Up JP Expiry : 0d 00:00:08
Up JP Rpt : Not Joined StarG Up JP Rpt Override : 0d 00:00:00
.
Rpf Neighbor :
Incoming Intf :
Outgoing Intf List : R3_1/1/2
.
Curr Fwding Rate : 0.0 kbps
Forwarded Packets : 0 Discarded Packets : 0
Forwarded Octets : 0 RPF Mismatches : 0
Spt threshold : 0 kbps ECMP opt threshold : 7
Admin bandwidth : 1 kbps
-------------------------------------------------------------------------------
Groups : 1
Short and sweet
Multicast on the 7750 – Quick Intro
I’ve been feeling somewhat lethargic since passing my CCIE. I think it’s actually some sort of trauma, going from 100 in a 50 zone to a dead stop and just lying on the pavement in the rain. I am really struggling with motivation to do anything really outside of work so it’s time to throw off the shackles of post-CCIE depression and get back to doing something interesting. I’m going to be doing some stuff with multicast on the 7750s so this is the first post on it. I haven’t had time to actually do anything of much substance in the lab on it yet so I just knocked up a quick bit of PIM to highlight how easy it is to get basics up and running. It’s not very interesting but it’s a start. I plan to get in to Rosen and mLDP stuff in the future and do a post on inter AS VPN between SROS and XR, maybe Junos if it treats me nice.
First the topology: R3 and R4 will be PIM neighbours with R4 being our RP.
OK let’s get PIM working:
R4
config router pim
interface system
exit
interface to_R3_1/1/2
exit
R3
config router pim
interface system
exit
interface to_R4_1/1/2
exit
Don’t forget your CPM filters will need to allow PIM through. The above was done on an SR1 which doesn’t support them but they would look something like this:
configure system security cpm-filter ip-filter entry 100
match protocol "pim"
action accept
!!Don’t forget how dangerous misconfiguring filters can be or you will be in the car with your console cable to recover the device!!
Right that should be it for PIM, let’s see if we have neighbour lift off.
*A:R3# show router pim neighbor
===============================================================================
PIM Neighbor ipv4
===============================================================================
Interface Nbr DR Prty Up Time Expiry Time Hold Time
Nbr Address
-------------------------------------------------------------------------------
R4_1/1/2 1 1d 18:47:24 0d 00:01:21 105
34.34.34.4
-------------------------------------------------------------------------------
Neighbors : 1
Great stuff, now we will configure R4 as the RP (bsr and rp candidate) and make sure R3 figures this out. We will use the system address of R4
R4
config router pim
rp
bsr-candidate
address 44.44.44.44
no shutdown
exit
rp-candidate
address 44.44.44.44
no shutdown
exit
exit
And the proof/pudding relationship:
*A:R3# show router pim status | match post-lines 13 BSR
BSR State : Accept Preferred
Elected BSR
Address : 44.44.44.44
Expiry Time : 0d 00:01:19
Priority : 0
Hash Mask Length : 30
Up Time : 1d 18:39:01
RPF Intf towards E-BSR : R4_1/1/2
.
Candidate BSR
Admin State : Down
Oper State : Down
Address : None
Priority : 0
Hash Mask Length : 30
.
Candidate RP
Admin State : Down
Oper State : Down
Address : 0.0.0.0
Priority : 192
Holdtime : 150
So we can see R3 has in fact learned R4 is the BSR. Just to illustrate the point that R3 is not in the running for RP, we can see that both RP and BSR candidate are admin down by default.
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