How does the internet work - We know what is networking
Policy-Based Routing Configuration Here we will show different examples for configure specific PBR types: Enabling PBR on the Router Fast-Switched PBR Local PBR CEF-Switched PBR Enabling PBR This command will define that the router will use PBR and that the PBR will use route-map named TEST. R1(config)# route-map TEST permit 10 Defines a route map […]
We’ve done a few shows now on Ethernet Fabrics where we have been getting deep into the different technology options and different vendor implementations. Avaya has sponsored this show where we actually interview customers who were early adopters of fabric-based and talk about what drove these customers to implement a network fabric, how they went […]
The post Show 136: Avaya – Considerations for Turning your Network into an Ethernet Fabric – Sponsored appeared first on Packet Pushers Podcast and was written by Greg Ferro.
This post represents the solution and explanation for quiz-6. Running dynamic routing protocols over tunnels can result in recursive problems. Read more to understand the problem and some solutions.
You are a network engineer of a company that provides MPLS services to more customers. Your teams tries to increase the redundancy, but instead they receive complaints that connectivity is broken. What's wrong?
You have recently moved to a new company as a network administrator and you've started doing an audit of the existing network. Your network uses an end-to-end QOS approach between multiple offices. Access switches trust QOS markings received from IP Phones and higher layer devices trust the markings received from access switches, as seen in diagram below.
Recently I had to recover the admin password on the Nexus 5548. The Cisco doc was a little bit uncleared so I figured I’ll make some notes on it.
First thing reboot the switch. The power supplies on these don’t have a on/off switch so you’ll have to pull the power cable.
When you see the output of “Loading system…” press the break command sequence Ctrl+]. This will bring you into the boot mode:
Version 2.00.1201. Copyright (C) 2009 American Megatrends, Inc. Booting kickstart image: bootflash:/n5000-uk9-kickstart.5.2.1.N1.1b.bin.... ............................................................................... ........................Image verification OK INIT: I2C - Mezz absent Starting system POST..... Executing Mod 1 1 SEEPROM Test:...done (0 seconds) Executing Mod 1 1 GigE Port Test:....done (32 seconds) Executing Mod 1 1 PCIE Test:.................done (0 seconds) Mod 1 1 Post Completed Successfully POST is completed can't create lock file /var/lock/mtab~193: No such file or directory (use -n flag to override) nohup: redirecting stderr to stdout autoneg unmodified, ignoring autoneg unmodified, ignoring Checking all filesystems....r. done. ^]Loading system <
I was interested to see what commands are available in this mode, there are few that I’ll use for the recovery (->):
switch(boot)# ? Continue reading
So recently I had to configure an OSPF adjacency between two routers.
I thought simply permitting multicast traffic to the All Routers and All DR/BDR Routers would permit OSPF Hellos across the link and allow OSPF adjacencies to form. In fact what I saw was routers entering the EXSTART state and the neighbourship failing. I checked the manual, for an OSPF adjacency to form, the following conditions need to be satisfied:
- Area IDs need to match
- Neighbours need to be on the same subnet
- MTUs need to match
- Hello/Dead timers need to match
- Authentication (if any is configured)
So, what I saw was the routers entering the EXSTART state and the neighbourship dropping. Bear in mind, at this point, the only thing permitted through the firewall both ways was multicast traffic to 224.0.0.5 (the AllSPF Routers multicast address) using the OSPF protocol (IP protocol 89). So for some reason the DBD exchange was not taking place.
My initial reaction was to check MTU size. I’d seen a similar issue before where an MTU mismatch (jumbo frames on one side, 1500 bytes on the other side) meant while the non-backbone area’s routes made Continue reading
