In this quick article, I’m going to show you how OAM LFM 1 can be used on MPLS L2VPN ACs to detect point-to-point connectivity faults on Junos. OAM LFM can be extremely helpful to enhance the AC (Layer 2) connectivity troubleshooting when you don’t have back to back physical connectivity on the PE-CE Ethernet link. This lack of back to back Ethernet connectivity, for instance, can arise when you have an underlying transport technology such as DWDM. In order to simulate this environment, I’ll run my entire topology (Figure 1) on virtual Ethernet bridges, which also have this lack of back to back physical connectivity between the two endpoints (i.e., even if you shut down one side of the link, the Ethernet link will still be perceived as up from the other endpoint’s perspective).
Pseudowire redundancy is key when it comes to eliminating a single point of failure, such as PW, AC and PE, in certain network designs as far as MPLS L2VPN services (e.g., VPWS and VPLS). When configuring pseudowire redundancy on Junos, you can either leave the backup PW in
standby or in
hot-standby mode. In this article, I’m going to compare both modes and point out some major benefits and drawbacks that you might want to take into account if you ever need to use PW redundancy in your network.
There are some nuances that you have to take into account if you need to interoperate MPLS L2VPN Martini (LDP VPWS) between Juniper (vMX) and Cisco (CSR1000v - IOS-XE). In this interoperability case, I’m going to use
VC-type 4/tagged mode (i.e., which in a nutshell, is the mode where you can use SVLANs on the ingress PE to differentiate between your L2VPN customers). If you need further or specific information about this mode, I’d suggest you take a look at the RFC4448 1.