12-02-2017 02:06 PM - edited 03-01-2019 01:41 PM
We have a network consisting of a 2x 5k core, 2x 5k DC distributions, 2x2 5k DC L2 aggregation and 2x 3850-48XS Campus L3 distribution (see attachment). The rendezvous points (RPs) are being shared on the cores switches via MSDP and all L3 devices point to the shared anycast-rp IP address as to their single RP IP address with an ACL limiting the stream to the 239.0.0.0/8 range.
The core switches talk to every L3 distribution switch exclusively via L3 routing (EIGRP). The DC distributions switches do create vPC connections to the end-of-rack 5k switches which connect several 2k FEXes. The multicast source is connected single-homed to one of the FEXs and the receiver on the Campus distribution. The source is streaming 10 different streams mapped to 10 different mcast addresses (all in 239.0.0.0/8 range).
The problem is, that I can randomly watch just every other multicast stream. In other words my VLC app is able to open/join just 4 to 5 streams of the streamed 10!
I have troubleshooted very deeply and all seemed pretty well. Than I got a thought to disable one L3 device after the other, step-by-step, since this behavior felt like a redundancy problem. After I shut down the secondary DC distribution switch (DC2-DC_distri) - BINGO! >>> every stream was funcitoning immediately properly and the switching between programs went blazing quick.
Do you have any thoughts, what could cause such abnormal behavior? After re-enabling the DC2 distribution, the problem came again! So just a plain reboot of a networking device didn't solve the problem. Just the shut down of this particular device solved it..
The configuration is prety simple. Every L3 interface has "ip pim sparse-mode", EIGRP routes everything to everything - basically every destination has two equal paths to get to. A permanent ping from source to destination was working stable for hours without loosing a single echo. So it has to have something to do with multicast routing or some strange vPC limitation.
Thanx for every single hint!
Solved! Go to Solution.
12-04-2017 12:58 AM
Probably - I FOUND THE SOLUTION!
I implemented following command on both L3 DC Distribution switches:
SWITCH(config)# vpc bind-vrf <TV_VRF> vlan <not_used/defined_VLAN>
DC1-DC_Distri(config)# vpc bind-vrf IPTV vlan 4000
DC2-DC_Distri(config)# vpc bind-vrf IPTV vlan 4000
Just implement this command on both L3 vPC Nexuses with the VRF where multicasts are being used and choose a VLAN which you HAVE NOT defined! It should work then.
12-02-2017 08:11 PM
12-03-2017 01:39 AM - edited 12-03-2017 01:50 AM
Hey Rick. Thanx for the fast answer.
Couple of questions
1. What exactly do you mean by "straight layer 3 interfaces and do ECMP"? Every L3 distribution switch is connected via L3 P2P networks (all are /31 because of IP address saving) to the core. I am using
2. I found here NX5600 PIM - Bind-VRF Configuration to vPCs a small chapter of configuring Bind-VRF which could possibly solve this issue. But the syntax is described pretty weird. I am not sure on which device(es) to configure it, which VRF and which VLAN to pick as the right one. Do you know this feature and/or do you have experience with it?
Thanx
12-03-2017 07:58 AM
12-03-2017 09:01 AM
Do you mean Rick, to remove the vPC port-channels between aggregation and distribution in the DC and make routing between these two layers?
12-04-2017 12:58 AM
Probably - I FOUND THE SOLUTION!
I implemented following command on both L3 DC Distribution switches:
SWITCH(config)# vpc bind-vrf <TV_VRF> vlan <not_used/defined_VLAN>
DC1-DC_Distri(config)# vpc bind-vrf IPTV vlan 4000
DC2-DC_Distri(config)# vpc bind-vrf IPTV vlan 4000
Just implement this command on both L3 vPC Nexuses with the VRF where multicasts are being used and choose a VLAN which you HAVE NOT defined! It should work then.
12-04-2017 10:20 AM
Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: