Network MacGyver

Jun 10

Configuring Cisco IOS router for OpenDNS dynamic updating

Do you run a branch office (or a home lab network) with a Cisco IOS-based router? Do you use OpenDNS? I was running into an issue where every time my DHCP address changed on the external internet connection, I’d have to go into the OpenDNS panel, and reset my IP address. I discovered however, that OpenDNS supports the DynDNS HTTP method for dynamically updating my IP address in their system.
version 15.4
ip ddns update method opendns
interface FastEthernet4
 description External Network
 ip ddns update opendns
 ip dens update hostname NETWORK-LABEL-IN-OPENDNS-PORTAL
 ip address dhcp
 ip nat outside

Jun 09

TCAM Allocation Adjustment Procedures for CAT 6500 and 7600 -

With the consistent growth in the routing table (currently at ~504261 routes), many older routers are struggling to deal with the size of the IPv4 routing table. This article documents how to adjust the TCAM allocations in the 6500 and 7600 platforms from Cisco. While this procedure doesn’t increase the size of the FIB TCAM, what it does do is allocate more of it to IPv4, and less to IPv6.

As such, it should be only undertaken as a temporary measure — long term these routers need to be upgraded. Of particular significance is the Sup720 card that has an extremely wide deployment. The Sup-2T card supports dynamic allocation of it’s 1 million FIB TCAM entry spaces between IPv4 and IPv6. This is the preferred upgrade path, as the Sup-2T card can also be used in the successor chassis to the 6500, the Catalyst 6800.

Apr 01

Half way there! #gottacatchemall #pokemon

Half way there! #gottacatchemall #pokemon

Mar 07


Feb 27

Pokémon is coming to Netflix -

I am of course excited about this for the kids. Yes. The kids.

Jan 17

PajamaDuty: PagerDuty Alerts Right In Your PJs -

Every month at PagerDuty, we try to one up one each other during our Hack Day.