Network Humor: Partial Mesh

Partial Mesh [pahr-shuhl mesh] noun A type of networking where each node must not only capture and disseminate its own data, but also serve as a _relay_ for other nodes, that is, it must collaborate to propagate the data in the network. What happens to your screen doors when you get cats Image and definition credit: Wikipedia

Network Humor: Partial Mesh

Partial Mesh [pahr-shuhl mesh] noun A type of networking where each node must not only capture and disseminate its own data, but also serve as a _relay_ for other nodes, that is, it must collaborate to propagate the data in the network. What happens to your screen doors when you get cats Image and definition credit: Wikipedia

BGP between Cisco Nexus and Fortigate

It is not uncommon to find that different vendors have slightly different implementations when it comes to standards technologies that should work seamless. I recently came across a BGP capability negotiation problem between a Nexus 7000 and a client Fortigate. Today’s post is not teaching about any new technologies, but instead showing the troubleshooting methodology […]

Neighbor Solicitation – IPv6’s Replacement for ARP

Like most others that start tinkering with IPv6, I quickly learned that there was no such thing as broadcasts on v6 networks. Since I thought that was a pretty revolutionary concept, I started thinking about all the protocols that until now have relied upon the ability to send via broadcast. The first that came to mind was ARP, which resolves known IP addresses to unknown MAC addresses by sending to the Layer 2 broadcast address of FF:FF:FF:FF:FF:FF.

Neighbor Solicitation – IPv6’s Replacement for ARP

Like most others that start tinkering with IPv6, I quickly learned that there was no such thing as broadcasts on v6 networks. Since I thought that was a pretty revolutionary concept, I started thinking about all the protocols that until now have relied upon the ability to send via broadcast. The first that came to mind was ARP, which resolves known IP addresses to unknown MAC addresses by sending to the Layer 2 broadcast address of FF:FF:FF:FF:FF:FF.

Neighbor Solicitation – IPv6’s Replacement for ARP

Like most others that start tinkering with IPv6, I quickly learned that there was no such thing as broadcasts on v6 networks. Since I thought that was a pretty revolutionary concept, I started thinking about all the protocols that until now have relied upon the ability to send via broadcast. The first that came to mind was ARP, which resolves known IP addresses to unknown MAC addresses by sending to the Layer 2 broadcast address of FF:FF:FF:FF:FF:FF.

Virtual Switching System (VSS) on Cisco Catalyst 6500

I’m currently working on a project that, among other things, involves the installation of two Catalyst 6509 switches. I was recently shown a redundancy feature that I had never heard of before called Virtual Switching System (VSS). The more I looked at it, the cooler it was. The main reason for VSS is something that is typically addressed when there are redundant routing platforms on a network. There are actually quite a few solutions that can be used in the presence of redundant devices, such as the popular and Cisco-proprietary Hot Standby Router Protocol (HSRP), or the IETF open standard Virtual Router Redundancy Protocol (VRRP).

Virtual Switching System (VSS) on Cisco Catalyst 6500

I’m currently working on a project that, among other things, involves the installation of two Catalyst 6509 switches. I was recently shown a redundancy feature that I had never heard of before called Virtual Switching System (VSS). The more I looked at it, the cooler it was. The main reason for VSS is something that is typically addressed when there are redundant routing platforms on a network. There are actually quite a few solutions that can be used in the presence of redundant devices, such as the popular and Cisco-proprietary Hot Standby Router Protocol (HSRP), or the IETF open standard Virtual Router Redundancy Protocol (VRRP).

I Am “Cisco Man”

Hello. Let me begin by saying you have arrived. Pardon me, where are my manners? I am CiscoMan - the comforting presence at the top of a large number of Cisco documents such as configuration and installation notes for Catalyst switches. I’m here to tell you that everything is going to be alright - that it’s okay to be scared. CiscoMan is here to help you out. Believe me, you’re not my first.

I Am “Cisco Man”

Hello. Let me begin by saying you have arrived. Pardon me, where are my manners? I am CiscoMan - the comforting presence at the top of a large number of Cisco documents such as configuration and installation notes for Catalyst switches. I’m here to tell you that everything is going to be alright - that it’s okay to be scared. CiscoMan is here to help you out. Believe me, you’re not my first.

Playing hide and seek with JunOS

JunOS has some commands which either are unsupported, do not work in platform you're using, undocumented or unnecessary for vast majority of operators, these commands are hidden in the UI so they are only accessible if you know what (and more importantly why) you want (them).

Today I was searching for a way to quiet my SRX210HE-POE as it makes annoyingly lot noise, I failed to find configuration way to force it to normal spinning speed, but I did notice that CLI exposes hidden commands. I've actually found same in IOS several years back and wrote little perl script to search for them (exec only), it proved bad idea as several of them purposely crash your system. If you want to dig deeper, in IOS difference is incomplete and invalid command, however actually some commands are truly hidden in IOS, particular example is the toggle for unsupported transceivers.

Neither the JunOS nor IOS issue are something you can blame vendor at, vendor isn't trying to stop you from using them, they just want to be very clear that if you use them TAC ain't go your back.

The code is quick 2h hack (running it takes longer, but I'm certain Continue reading

Where Did All The Time Go?!?

I woke up this morning and realized that I had broken my 3-week long streak of blog posting, where I had gotten in the habit of making a new post nearly every day of the week. Since I have been unemployed for the past three weeks and my primary priority was to study for the CCNP, it was easy to come up with new blog content at a relatively rapid pace.

Where Did All The Time Go?!?

I woke up this morning and realized that I had broken my 3-week long streak of blog posting, where I had gotten in the habit of making a new post nearly every day of the week. Since I have been unemployed for the past three weeks and my primary priority was to study for the CCNP, it was easy to come up with new blog content at a relatively rapid pace.

BGP: Weight and Local-Preference

It’s important to remember that since BGP is the routing protocol of the internet, there are quite a few attributes that it uses to give preference to a single route out of several redundant paths to a given destination. I was recently contemplating several of these and it occurred to me that two of these attributes in particular are pretty similar. I’d like to compare and contrast them and give reasoning for situations that call upon one or the other.

BGP: Weight and Local-Preference

It’s important to remember that since BGP is the routing protocol of the internet, there are quite a few attributes that it uses to give preference to a single route out of several redundant paths to a given destination. I was recently contemplating several of these and it occurred to me that two of these attributes in particular are pretty similar. I’d like to compare and contrast them and give reasoning for situations that call upon one or the other.

EIGRP Unequal-Cost Load-Balancing

In a previous post, I explored the basics of IP routing, and in the process, we discovered an interesting default feature of OSPF. When there were two OSPF routes in the routing table to a network, and both routes had the same cost, the router performed load balancing between the two. Take, for instance, the following route: 172.16.2.0 [110/12] via 1.1.1.13, 00:09:24, FastEthernet0/0 [110/12] via 1.1.1.2, 00:09:24, FastEthernet0/1 In this example, every packet sent would take one of two routes.

EIGRP Unequal-Cost Load-Balancing

In a previous post, I explored the basics of IP routing, and in the process, we discovered an interesting default feature of OSPF. When there were two OSPF routes in the routing table to a network, and both routes had the same cost, the router performed load balancing between the two. Take, for instance, the following route: 172.16.2.0 [110/12] via 1.1.1.13, 00:09:24, FastEthernet0/0 [110/12] via 1.1.1.2, 00:09:24, FastEthernet0/1 In this example, every packet sent would take one of two routes.
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