Eric Stewart: Running Off At The Mouth

Tag: cisco

Nexus 7700 Part VI: vPC Part II: You Can’t Use The Peer-Link For Everything

by on Feb.21, 2015, under Networking, Technology

$JOB doesn’t have as much of a testing environment as one might like to have, so sometimes you discover issues during implementation that, once you resolve them, you can’t go back and pick apart. An issue with the vPC Peer link appears to have prevented one of our 7710’s going into our data center from properly forming an OSPF adjacency with the DR.




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Nexus 7700 Part V: TCAM Woes and Solutions

by on Jan.21, 2015, under Networking, Technology

I get an error message while pasting in some VLAN interfaces:

ERROR: Module 1, 2, 10 returned status: Tcam will be over used, please enable bank chaining and/or turn off atomic update.If bank-chaining is enabled on other modules and this is a new linecard insertion,please enable bank-chaining prior to reloading this module.

Well, this (I think) is what it means, and how I resolved the situation.

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Nexus 7700 Part IV: vPC – Basic Configurations and Annoyances

by on Jan.08, 2015, under Networking, Technology

Having been silent about my Cisco Nexus 7700 work for a while, I come across something that irked me a little bit while trying to configure our 7700 pair to replace the 6500s, involving Virtual Port Channels. So here’s what Virtual Port Channels are and how they basically work, as well as one or two things that you might want to be aware of. So, this may end up getting quite long …







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Nexus 7700 Part III: Breakout Interfaces

by on Jul.15, 2014, under Networking, Technology

It is possible on the Nexus 7700 line, with certain optics, to break out 40Gb (and eventually 100Gb) to 4x10Gb interfaces (no one knows for sure what 100Gb will do – it will either be 8x10Gb or 10x10Gb). In this post I go over how $JOB is doing it (at least with the 40Gb) and what you need to be aware of. I do touch a little bit on the 100Gb breakout future and explain why we were looking to do it.







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Nexus 7700 Part II: Racking a Cisco Nexus 7710

by on Jul.08, 2014, under Networking, Technology

We racked our Nexus 7710 recently. Here’s some of the things you might need to know regarding getting this monster of a chassis into a rack.







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So I Went To My Second Cisco Live …

by on Jun.25, 2014, under Life, Networking, Technology

I figured I should get this written while I can, and before it all fades away from my brain … here’s my thoughts on Cisco Live and some advice for future first-time attendees.







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Nexus 7700 Part I: Power and Playing With Supervisors

by on Jun.23, 2014, under Networking, Technology

So we powered on our first to arrive Nexus 7706s (two of them). Here’s some notes so far.







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Perl’s Net::SNMP and get_table() – Bulk vs Next Request

by on Sep.27, 2013, under Networking, Technology

An attempt to communicate an issue (and the solution) I ran into with Perl’s Net::SNMP function “get_table”, that would result in a “The message size exceeded the buffer maxMsgSize of 1452” error. It took a couple of packet captures and Googling to figure out why this problem was occurring and implement a fix.







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Packet Captures and Offloaded Functions

by on Sep.05, 2013, under Networking, Technology

A fellow engineer attempting to debug a jumbo frames issue was seeing what should have been a bunch of fragmented frames as a single 13,000 byte frame. Once he figured out why, I was told to fix it. Here’s my solution.







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CentOS, cisco monitor ports, and IPv6

by on Jan.15, 2012, under Networking, Technology

I finally got the job I’ve been wanting for, oh, nearly a decade now (if not more). In this job I’m the go-to admin for the servers (almost all CentOS based) that support a large (3000+ device) network. Cisco routers run the network, and we have servers that are connected to “monitor” ports. One of the principle tasks of these servers are to allow network engineers to run packet captures. Thing is, interesting things can happen as far as IPv6 is concerned when you have systems getting IPv6 router advertisements on server interfaces that don’t actually do more than just accept packets …







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