Egress Peer Engineering: building blocks
Since exploring the EPE basics, now it’s time to understand the building blocks of the solution.
Summary
Overall, there are 3 elements of the EPE solution:
- Egress routers allocate MPLS labels per egress peer and advertise them
- Ingress routers or
Egress Peer Engineering: basics
Egress Peer Engineering extends regular BGP policies to provide more flexibility.
Why use Egress Peer Engineering
When a network operator has multiple external connections, such as IP transit, private peerings or Internet Exchange (IXP), there is often a need to …
Poor man’s Traffic Engineering
Segment Routing allows the network operator to deploy Traffic Engineering even with the most basic routers that support the bare minimum of features.
What is traffic engineering
Traffic engineering is a set of techniques to influence the path a particular …
Making Segment Routing user-friendly
Segment Routing was supposed to make MPLS easier and give more power to network operators. Sadly, vendors decided to make it harder by selling weird protocols and over-engineered controller bloatware.
MPLS is actually great
Despite some anti-MPLS marketing from SD-WAN …
Explicit Null in Segment Routing
MPLS is such a user-friendly technology it needs a special label that does nothing.
Why explicit null
Normally, the penultimate router in the LSP removes (pops) the top transport label, so that the egress LSR will deal either with the …
LDP and anycast routing
My recent post about Anycast in Segment Routing led to an interesting argument on whether other MPLS transport protocols can do anycast routing.
In that post, I wrote:
……MPLS is not a pure packet switching technology, but has a control
Anycast in Segment Routing
MPLS or Anycast Routing – for a long time, you had to choose one. Segment Routing allows you to have both.
Introduction
It’s hard to overstate how important anycast routing is. DNS root servers and CDN rely on it to …
ARP problems in EVPN
In any L2 overlay network, ARP handling will always remain a big pain for network operators.
This post explains why you should always set ARP timeout to less than 5 minutes in L3 EVPN, and always be cautious of potential …
How to troubleshoot routing protocols session flaps – part 1
Instability of routing protocol sessions – or, in the network engineers’ slang, flaps, is by far the most common and the most basic routing problem that ever occurs.
Shortly after beginning to write this post, I realized it will …
Equal Routes
In highload cloud networks there is so much traffic that even 100G/400G port speeds do not suffice, so sharing the load over multiple links is the only feasible solution.
Introduction
ECMP stands for Equal Cost Multi-Path – when a route …
Segregated Routing
For any network that provides routing services to customers it is important to segregate them in different virtual topologies that don’t interfere with each other.
Network Virtualization
This post is not about NFV, but it is important to understand …
Close to the Edge
PE-CE routing in MPLS L3VPN is an important topic which confuses a lot of people. Thanks to EVPN, it is now used not only in ISP but also DC networks.
Fundamentals of PE-CE routing
Usually either static routing or eBGP …
On Duplicates
Packet duplication wastes bandwidth and can lead to significant network performance degradation or even outages.
In multicast routing, packets are replicated by the network, so there is always a fundamental risk of duplicate traffic. Special safeguards exist to avoid …
Topology Dependent LFA
Fast convergence after failures has always been an important part of ISP network design.
When a failure is detected, it takes a while until the routing protocol propagates new information throughout the network and all routers update their FIB. …
Barbaric Balancing
Recently I stumbled upon the IETF draft about PIM Designated Router Load Balancing (DRLB) and it reminded me of something absolutely barbaric.
Introduction
In L3 multicast, load balancing is simple. If the RPF route is ECMP, the router can choose …
Seamless Suffering
This story is about the importance of remembering networking fundamentals when dealing with advanced routing topics.
Overview of Seamless MPLS
Seamless MPLS is a really neat design for large ISP networks. The idea is to overcome the scalability limitations of …
What happens if you redistribute BGP full view into OSPF
Yes, this has already happened to many networks across the globe. And for sure will happen again. Maybe to your network?
TL;DR:
The network will go down. OSPF sessions will start flapping, some routers might run out of memory and …