Hellos are sent and then it just neighbors up like an IGP – neighboring up specific to that interface. The assumption I see people making here is the assumption that LDP will neighbor up on the interface similarly to an IGP. I find it common that without specific knowledge we tend to assume things. So if R1 is transmitting and receiving LDP hello messages… then why do we not have a LDP neighbor between R1 and R2? R1 is Transmitting (xmit) and Receiving (recv) LDP Hello Messages on gig0/0/1.Let’s deal with just what I’m showing above. Let’s take the output of this command in two pieces. Origin incomplete, metric 0, localpref 100, valid, internal Inner/VPN label: This label will be advertised by R3 to R1 via BGP vpnv4 for the prefix 14.14.14.3. To see whether or not R1 has knowledge of the Inner/VPN label to use for vrf Customer1 destination IP 14.14.14.3 we first kinda need knowledge as to how R1 is supposed to learn the label. The order I would troubleshoot these in is first to start with the Inner/VPN label. Where will these labels come from? What protocol(s)? We need to know so we can see if we are getting the labels we need to get thru the “ plumbing”. In our specific environment R1 needs to send the ping out with 2 LABELS: How is R1 supposed to format the packet as it tosses it into the “ MPLS 元VPN plumbing“? To me, in order to troubleshoot this, we need to know more about the logistics of how MPLS 元VPN works.
The above facts are 100% normal in a MPLS 元VPN environment.The P router (R2) has the global table routing only and does NOT have 14.14.14.1 or 14.14.14.2.Since the device I picked in our first pass here is a PE, it would be beneficial to know what the PE is supposed to do with the packet after it finds the destination is in the VRF routing table.
Knowledge is what is key to this ability to tease out what facts are also clues to follow.īearing that in mind what knowledge do we need here to help us troubleshoot what is going on? We need to be able to identify which ones are also clues so we can follow them. “CLI show commands” on devices) we will get a crap ton of facts. Remember: Knowledge is Keyīefore we begin we need to remember that “knowledge is key”. So time to go back to the “ looking for clues first pass“. In the previous blog we gathered the facts, collected the clues, interviewed the witnesses, questions the suspects and fixed everything that was not correct in the BGP configs.īut we still can’t ping. The “First Pass”, for me, is the “ looking for clues“ phase. In this part 2 blog we will focus on the MPLS portion.Īs we go along… continue to keep in your mind the Network Detective Mantra “Be Prepared, Find the Suspects, Question the Suspects, Improve”įirst Pass: Pick a PE and Check the Basicsĭeja vu eh? Weren’t we just here in the last blog? Didn’t we “do” the first pass already? Why are we back? Ready to begin? Grab your Network Detective badge and something to take notes with. We found a number of things not configured correctly and we fixed them.Īnd yet… while we fixed many things that needed to be fixed in the BGP…. are the advertisements being received? In part 1 we stayed focused on the knowledge of the IP addresses and stayed in the BGP… interviewed witnesses… gathered facts and followed clues.
We started, like any ping troubleshooting, on the IP subnets themselves – do they exist in the routing table?… are they being advertise? …. If (document.Ready for part 2 of our Network Detective MPLS 元VPN Ride-Along? In part 1 we were presented with the “Case of the Failed 元VPN Ping”. Stuck on back of bumper and passed the MOT, tester said ‘does the job’ and indeed it does. Needed these as my car rear reflector had been knocked out by a hit and run. Needed red reflectors to comply with new laws for motorcycle trike. The reflecters were used on a gate that opened on to a road and are both effective and a good value easy fit product. I recently bought these reflectors and after a very simple installation was more than pleased with their performance as they are excellent at the normal price but when I went to the till was even more delighted to find that customer caring Halfords had reduced them to half price ,what a top shop. These stuck onto painted metal very well just as described
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