Tech Library
RSVP – install option
1. Intro By default, only /32 prefixes are installed in the inet.3 table. Using the install option, you can add additional prefixes to inet.3. By including the active parameter, the prefix is also added to the inet.0 table, which means that the IGP can also use this prefix. Remember that by default only BGP can […]
RSVP – OAM BFD
1. Intro We can configure OAM BFD for LSPs to detect LSP data plane faults. To bootstrap the OAM BFD session, there is an initial exchange of MPLS Ping packets (Echo Request/Reply) between the ingress and egress routers, that is using UDP port 3503. After the initial MPLS Ping exchange, the routers will exchange BFD […]
RSVP – soft-preemption/adaptive
1. Intro Essentially, we are discussing here about the make before break (MBB) feature. You will see MBB is enabled by default for some features, like periodic re-optimization of LSPs. By default, MBB is disabled for LSP preemption, but we can change this with either soft-preemption or adaptive. Soft preemption attempts to establish a new path for […]
RSVP – Link/Node Protection
1. Intro The Junos implementation of facility backup is link protection. This feature is interface based rather than LSP based. Whereas fast reroute is trying to protect the whole LSP (1:1 protection), link protection (1:n) protects only the link, however, it can protect multiple LSPs. A bypass LSP must terminate on the downstream LSR. Bypass […]
RSVP – fast reroute
1. Intro Fast reroute can dramatically reduce packet loss in the case a primary path fails. Even if you have a secondary path signaled with the standby feature there is still the possibility of many packet drops. This happens because the message for the failed path must still travel back towards the ingress LSR so […]
RSVP – Secondary Paths
1. Intro In the previous example we tested link coloring with multiple LSPs to the same destination, which is not ideal. In this post we will configure Secondary paths. By default, when network failures occur along the path of RSVP signaled LSPs, traffic will be dropped. The ingress LSR continues to send traffic until a […]
RSVP – Link Coloring
1. Intro Administrative groups provide the ability to mark the interfaces with similar characteristics in a common group. Based on these groups you can restrict the LSPs to use a certain path in the network. Marking the interfaces is known as coloring but is actually based on setting the affinity bits on interfaces. Up to […]
BGP – 6PE
1. Intro We have a small service provider which is providing IPv4 internet services. It has a really simple design with a flat OSPF network, and internal iBGP session via a Route Reflector. No MPLS at this stage. 2. Dual-Stack IPv6 Now, we are being asked to add IPv6 to our network. One way to […]
BGP – RR next hop resolution
1. Intro We have a small service provider with an small MPLS network with a couple of L3VPNs. What matters here is the RR configuration: RR2 will not forward traffic, so we are being asked to remove the LDP configuration. But this will immediately create problems, next hop resolution is no longer working: In the […]
BGP – Inter-AS Option C
1. Intro BGP Option C is the most scalable Inter-AS MPLS L3VPN model. Unlike Options A and B, the PE routers exchange VPN routes directly, while the ASBRs only provide MPLS transport between the autonomous systems. Find next our test topology for this post: Our aim is to have end to end connectivity for Cust-A […]