Here is the ANKI package for the flash cards: https://upw.io/u4/&1.1.C_Network_Challenges.apkg If you prefer the text, please read below. What is unicast flooding, in simple terms. Unicast flooding is when a switche receives a unicast frame but has no entry in its CAM table for the destination MAC adress, thus treats the frame as broadcast. Simply …
Category Archives: CCIE R&S
1.1.c (iii) Asymmetric Routing
Asymmetric routing is when a packet does not return on the same path it took to the destination. This isn’t always an issue, some times it is by design. However there are certain scenarios where it can lead to issues: 1. Asymmetric routing can cause unicast flooding of traffic in very specialized conditions (worse if …
1.1.c (ii) Out of Order Packets
Out of order packets are caused by bad load balancing or per packet load balancing. Technologies like CEF avoid out of order packets by doing a really good PER FLOW load balancing/load sharing. For TCP: Out of order packets to a receiver are a waste of 1. bandwidth and 2. CPU cycles 1. Packets …
1.1.c (i) Unicast Flooding
Unicast flooding is the result of switch receiving a unicast frame, but not having an entry for the destination MAC address in its CAM table. When a switch receives such frame, it will flood it out of all ports, hence the name unicast flooding. There are a few scenarios where this is common: 1. As …
1.1.b Flash Cards
Here are the 1.1.b flash cards I created, I have uploaded the Anki package, and then I will be pasting them as text here if you do not use Anki. Anki Package: https://upw.io/u2/&1.1.b_CEF_v_1.1_(2).apkg Flash cards in text: What does CEF stand for? Cisco Express Forwarding What does RIB stand for? Routing information base What …
1.1.b (iii) Polarization Concept and Avoidance
Moving on from load-balancing, let’s discuss CEF polarization, which is a problem already solved, however is still important to study. Let’s take the above diagram where all routers are utilizing the older iteration of CEF without Universal IDs. If 64 flows come into this router, CEF will equally distribute them across its 2 links. The …
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