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Posted on in Networking
There are a few network devices out there that allow you to connect, but don't give you an option to disconnect. For example, you might be stuck at a password prompt, but have no authentication details. Most telnet clients allow you to break these connections with the ^] (control-]) command. <acronym …
Posted on in networking
You may already know that the IEEE 802.1D specification recommends a maximum network diameter of 7 hops. What you may not know is that the number 7 is derived from a series of calculations based on various timers being tuned to their default values. If you are designing a …
Posted on in Networking
I saw this error message on a Cisco ASA 5540 today:
%ASA-3-210005: LU allocate connection failed
According to Cisco, this error means the standby unit was not able to create a new connection for stateful failover. The recommendation is to verify that the system has enough RAM.
OK...
# show memory …Posted on in Networking
Intranets are privately owned networks that operate like the public Internet in many respects. In most intranets, corporate users access company information via tools designed to run in web browsers. Intranets allow employees to share and access confidential corporate information. The benefit of these systems is that they operate …
Posted on in Networking
This is a revisiting of the Company X presentation regarding telecommunications.
Company X should utilize prevailing broadband technology in each store location to provide the lowest cost high-speed access to the Internet. In order to facilitate communication between each store and the company headquarters, a virtual private network (VPN …
Posted on in Networking
A buddy of mine is getting about 1 Mbps through his Cisco 2621XM based VPN.
Additionally, the CPU was maxed out during the transfer. (In my testing, I was
able to max out a 7 Mbps cable modem using the
Cisco VPN Client connected
to the same endpoint, so the …
Posted on in Networking
The IEEE802.16 standard defines five Quality of Service (QoS) classes.
UGS was designed to accommodate services that create fixed-size data packets on a regular basis. This class offers grants on a periodic basis and removes the need for subscriber unit access requests. This QoS class …
Posted on in Networking
Preserve Cisco router DHCP leases across a reboot by configuring a DHCP database agent, verifying successful writes, and choosing a storage target that fits the platform.
Posted on in Networking
Last week I mentioned that I was working on a Quality of Service (QoS) project. For those who are curious about QoS and how to get it working, here are the resources I found most useful. These resources are mostly Cisco specific, but the principles should be applicable in many …
Posted on in Networking
I decided I needed a standardized set of Quality of Service classification access-lists for some work I'm doing. Check out my Cisco QoS Classification ACLs page and let me know what you think.
If you have any ideas on how I can improve the lists, leave a comment here or …
Posted on in Networking
This week I tried upgrading a Cisco Catalyst 2960 to the newest software release — 12.2(46)SE. The upgrade went just fine, but I noticed that the monitoring software was throwing SNMP errors.
In case you don't know much about SNMP, an ifIndex identifies a specific interface on a …
Posted on in networking
I've been working on a standardized list of access lists to use in conjunction with QoS on Cisco routers and switches. I've tried to adhere as closely as possible to the Cisco QOS Baseline (pdf).
As I refine the ACLs, I'll keep this page up to date. If you have …
Posted on in Networking
I recently had the pleasure of working on a client's Cisco 2600 series router that had not been used in quite some time. Access lists on the vty lines and a misconfigured con line meant I was locked out. In a situation like this, the only way to gain access …
Posted on in Networking
Laurence F. Sheldon, Jr. just gave a great cable tag definition on the NANOG mailing list.
The tags should have a short (two or three word) description, the authority for the patch (person's name or position, order number, or trouble ticket number) and where the [other]{.underline} end of the …
Posted on in Networking
As you might recall, I had previously taken umbrage with Cisco's inability to forward a range of ports to a particular host. Many readers have offered suggestions and links to other documents around the Internet offering various solutions, but none of them really sat quite right with me.
In hindsight …
