uRPF Design Consideration
While the Anti-Spoofing uRPF technology and mechanism are well-known, determining when and where to apply it in Strict or Loose mode can be confusing. This writing aims to simplify understanding from a Design perspective and provide practical use cases. Why is uRPF...
Do We need P Routers in an MPLS Network Design ?
We sometimes hear that: An MPLS Network without P is not a real MPLS Network. A collapsed PE Network is incomplete or not a genuine MPLS design What exactly is a P and PE router : In MPLS, a P router acts as a vital link within the core network, connecting different...
BFD over LAG Design
You might face a situation where you're considering establishing a LAG port (whether using LACP, manual configuration, etc.), or perhaps you're planning a maintenance window and considering shutting down a link within a LAG port, assuming it won't affect the routing...
How to decode ESP packets within UDP encapsulation using Wireshark?
Have you ever found yourself in need of decrypting ESP packets nested within UDP encapsulation using Wireshark, especially when dealing with setups similar to those found in Cisco SD-WAN? Wireshark automatically performs this action for NAT-T UDP 4500 destination...
The Impact of BGP Update Delay
Consider a scenario where your network architecture features two redundant CE routers linked to two PE routers. In this setup, the PE routers are configured to transmit only the default route to the CE routers, particularly beneficial for Branch routers, which...
QoS – Should we assign a value for the default-class?
Here is how the CBWFQ (Class-Based Weighted Fair Queueing) allocation mechanism is described on Cisco website : "If excess bandwidth is available, the excess bandwidth is divided amongst the traffic classes in proportion to their configured bandwidths. If not all of...
Navigating the Network Design Requirements and Constraints
In network design, it is important to consider every aspect of the design process, whether it involves creating a new network from scratch, adding new technology, making changes to existing elements, merging or diverging networks, replacing technology, or adding new...
ECMP and Load Sharing on IP Fragments
Here is how IP fragmentation works: A Router receives a large IP packet that exceeds the MTU of its egress interface. The router divides the packet into smaller fragments, each with a size that is equal to its interfaces MTU egress interface. The router sets the "more...
Multipath eiBGP Design Review
There are plenty of documents online discussing Multipath BGP, but few seem to address the need for using eiBGP for load sharing (ie. eBGP and iBGP at the same time). Overview of the topics covered in this review: Why and when do we need eiBGP Multipath The pros...
My CCDE Journey : How I fought the final Boss – CCDE Practical Exam
The beast, the ultimate goal, the final boss, whatever you call it, the CCDE Practical exam is one of the hardest Network certification to have nowadays, Brief strategy (if you don't want to read all of the feedback, and want to begin your CCDE journey, here are...