Quality of Service (QoS) – Policing and Shaping Notes

Policers and shapers identify traffic violations in an identical manner, but treat them differently.  Policers perform instantaneous checks and immediately take action when a violation occurs.  Actions can include marking, dropping, and even just transmitting the packet.  Shapers on the other hand are traffic-smoothing tools.  Its objective is to send all traffic out a given interface, but to smooth it out so that it never exceeds a given rate – usually in order to meet SLAs.  Excess traffic is buffered and delayed until the traffic once again dips below the defined maximum rate.

Policer Shaper

Causes TCP resends as traffic is dropped

Delays traffic; involves less TCP resends

Inflexible; makes instant drop decisions

Adapts to network congestion by queuing excess traffic

Ingress or egress interface tool

Typically egress only

Rate limiting – no buffering

Rate limiting with buffering

While policing and shaping tools are not employed to directly provide QoS for real-time traffic, they do regulate/stabilize traffic flows so that unexpected bursts in data traffic do not induce jitter and latency that adversely affects real-time traffic.

Policers determine whether each packet conforms, exceeds, or violates the policies configured for traffic, and takes the prescribed action Continue reading

Operation (Unicorn?) Mincemeat, Counter Security, and a book about JWAS

In 1943, Spanish officials recovered the body of a spy from the Atlantic coast of Huelva.  The suitcase still attached to his arm contained Allied war plans, identifying Greece and Sardinia as the beachhead for the forthcoming assault on Italy.  Amazed by their luck, Axis forces redeployed divisions from Sicily, Northern France, and the Eastern […]

Author information

Glen Kemp

Enterprise Security Architect. Designing & deploying “keep the bad guys out” technologies. Delivering elephants and not hunting unicorns.

Please free to add me on , follow me on Twitter or check out my other blogs on Juniper J-Net, sslboy.net and SearchNetworking.

The post Operation (Unicorn?) Mincemeat, Counter Security, and a book about JWAS appeared first on Packet Pushers Podcast and was written by Glen Kemp.

Second CCIE, or CCDE?

“Should I get a second CCIE, or a CCDE?” A number of people have asked me this recently; in the process of answering those questions, I’ve developed a couple of lines of reasoning that I thought worth sharing here. No, I’ve not been posting much recently — I’m wrapped up in a bunch of different […]

Author information

Russ White

Russ White
Principle Engineer at Ericsson

Russ White is a Network Architect who's scribbled a basket of books, penned a plethora of patents, written a raft of RFCs, taught a trencher of classes, and done a lot of other stuff you either already know about, or don't really care about. You want numbers and letters? Okay: CCIE 2635, CCDE 2007:001, CCAr, BSIT, MSIT (Network Design & Architecture, Capella University), MACM (Biblical Literature, Shepherds Theological Seminary). Russ is a Principal Engineer in the IPOS Team at Ericsson, where he works on lots of different stuff, serves on the Routing Area Directorate at the IETF, and is a cochair of the Internet Society Advisory Council. Russ will be speaking in November at the Ericsson Technology Day. he recently published The Art of Network Architecture, is currently working on a new book in the Continue reading

7 Tips For Improving Your Communications Skills at Work

In my last article, I identified the importance of effective communication in the workplace. Today’s article is a follow-up that offers several suggestions meant to help individuals improve these skills. Some tips may be more or less relevant to the situations that are specific to an individual’s role. As I mentioned in my previous article,l […]

Author information

Paul Stewart

Paul is a Network and Security Engineer, Trainer and Blogger who enjoys understanding how things really work. With nearly 15 years of experience in the technology industry, Paul has helped many organizations build, maintain and secure their networks and systems. Paul also writes technical content at PacketU.

The post 7 Tips For Improving Your Communications Skills at Work appeared first on Packet Pushers Podcast and was written by Paul Stewart.

New York Seminar – Multicast & Product Updates

Date: September 12th, 2013
Time: 8:30am
Venue: The Westin at Times Square

Please join us for an informal breakfast seminar to discuss the IP routing management needs of organizations in the financial services, broadcast video, and other industries. Attendees will also receive a Packet Design product update from Matt Sherrod, Vice President of Products, and see a demonstration of the newly-released Multicast Explorer which offers unprecedented real-time and historical visibility into multicast routing operations as well as powerful modeling capabilities. In addition to breakfast, attendees will have a chance to win a Beats by Dre™ Bluetooth Speaker. 

Who should attend: Network routing engineers, network architects, planners and administrators; network operations engineers and managers, directors and vice presidents of network infrastructure and IP communications.

Seminar Registration - New York 2013

London Seminar – Multicast & Product Updates

Date: September 17th, 2013
Time: 8:30am
Venue: The Four Seasons London at Canary Wharf

Please join us for an informal breakfast seminar to discuss the IP routing management needs of organizations in the financial services, broadcast video, and other industries. Attendees will also receive a Packet Design product update from Matt Sherrod, Vice President of Products, and see a demonstration of the newly-released Multicast Explorer which offers unprecedented real-time and historical visibility into multicast routing operations as well as powerful modeling capabilities. In addition to breakfast, attendees will have a chance to win a Beats by Dre™ Bluetooth Speaker. 

Who should attend: Network routing engineers, network architects, planners and administrators; network operations engineers and managers, directors and vice presidents of network infrastructure and IP communications.

Seminar Registration - London 2013

Cisco Nexus vPC Config-Sync


In my previous blogs NX-OS vPC FEX config example and Configuring VSS Cisco 6500 and vPC, I've covered virtual Port-Channels in detail. For those new to this terminology, virtual port-channel or vPC makes a pair of Cisco Nexus 5K/7K switches (vPC peers) appear as a single logical switch to a downstream device. Arp tables, mac address tables and route tables can be synchronized across the vPC Peer-Link (link connecting the two peer switches). This provides great redundancy in typical Data Center networks. 

Every time I configure a Nexus environment at a Data Center, or a campus core, I have to explain to the end user that the configurations on the vPC peers are not synchronized. Say for example you configure Eth1/30 on Nexus-1, and forget to configure Eth1/30 on Nexus-2, and a device is dual homed to Eth1/30 on both Nexus switches, then when vPC failover occurs and vPC Primary/Secondary roles are switched over, the new primary switch will not have any configuration in store for Eth1/30, and this will cause a service disruption.

To avoid this, you have to be very meticulous and have matching configurations across both vPC peers. Or, you can use configuration synchronization available Continue reading

Understanding Flow Export Terminology

The variety of terms used to describe network flow export technologies and components can be pretty confusing. Just last year I wrote a post on web usage tracking and NetFlow that is already a bit obsolete, so here's an attempt to explain some of the newer terms and capabilities in use today.

NetFlow Version 5
NetFlow v5 is sort of the least common denominator in flow technologies. Almost all vendors and devices that support a flow export technology will do NetFlow v5. Because it's only capable of exporting information about packet fields up to layer 4, however, it's not flexible enough to use for analytics that require information about the application layer. NetFlow v5 tracks only the following data:
  • Source interface
  • Source and destination IP address
  • Layer 4 protocol
  • TCP flags
  • Type of Service
  • Egress interface
  • Packet count
  • Byte count
  • BGP origin AS
  • BGP peer AS
  • IP next hop
  • Source netmask
  • Destination netmask
Netflow Version 9
Netflow v9 was Cisco's first attempt at defining an extensible flow export format, defined in RFC 3954 back in 2004. It provides a flexible format for building customizable flow export records that contain a wide variety of information types. Many of the goals for Continue reading

EtherChannel – Quick and Dirty

EtherChannel allows you to aggregate several switch links into a single, fast, fault-tolerant, logical interface. 16 links can be defined for an EtherChannel, however, a maximum of 8 will be active at any one time.  The other links are placed on standby.

While having multiple links between two switches can possibly create bridging loops, EtherChannel avoids this by bundling the links into a single logical interface.  This logical interface can be configured as an access or trunk interface.

For ports to be members of the same EtherChannel, there are some restrictions. Ports must:

  • Belong to the same VLAN
  • Have identical STP settings
  • Have identical speed/duplex settings
  • Note: In addition, if the EtherChannel is to be used as a trunking interface, all ports must be in trunking mode, have the same native VLAN, and pass the same set of VLANs.

The full duplex maximum bandwidth for 8 links is as follows:

  • Fast EtherChannel (FEC): 1600 Mbps
  • Gigabit EtherChannel (GEC): 16Gbps
  • 10-Gigabit EtherChannel (10GEC): 160Gbps
  • Note:  This is theoretical; maximum bandwidth is not likely to be achieved due to unequal load balancing, and other factors.

Load Balancing

 

EtherChannel load balancing across the links can occur in a number Continue reading

Brocade Auth-Change-Wait-Time

 

The other day I was at work doing an interoperability test with Cisco and Brocade multilayer switches, and we ran into a strange issue that really highlighted my “tunnel view” to the Cisco world.

We were setting up basic OSPF stuff using md5 authentication and we couldn’t get the Cisco and Brocade to form an adjacency.  A debug ip ospf adjacency command on the Cisco switch revealed that the Cisco was using “type 2” authentication, and the Brocade was using “type 0”. 

Here’s a quick breakdown of the authentication types:

Type 0 No authentication
Type 1 Clear text authentication
Type 2 md5 authentication

I set up a SPAN on the Cisco switch and sure enough, we were getting the OSPF Hello packets from the Brocade with no authentication.

After some digging, it turns out the Brocade has an Auth-Change-Wait-Time command in interface configuration mode.  This is set to 300 seconds (5 minutes) by default.  While I don’t quite understand it, the description states it allows for graceful authentication implementation.  So after you enable md5 on the interface, it waits 300 seconds before actually sending OSPF Hellos with authentication.  We toyed around with it Continue reading

OSPF LSA Manipulation Vulnerability – 8/1/2013

Vulnerability Details

OSPF LSA Manipulation Vulnerability in Multiple Cisco Products

· Summary

Multiple Cisco products are affected by a vulnerability involving the Open Shortest Path First (OSPF) Routing Protocol Link State Advertisement (LSA) database. This vulnerability could allow an unauthenticated attacker to take full control of the OSPF Autonomous System (AS) domain routing table, blackhole traffic, and intercept traffic.
The attacker could trigger this vulnerability by injecting crafted OSPF packets. Successful exploitation could cause flushing of the routing table on a targeted router, as well as propagation of the crafted OSPF LSA type 1 update throughout the OSPF AS domain.
To exploit this vulnerability, an attacker must accurately determine certain parameters within the LSA database on the target router. This vulnerability can only be triggered by sending crafted unicast or multicast LSA type 1 packets. No other LSA type packets can trigger this vulnerability.
OSPFv3 is not affected by this vulnerability. Fabric Shortest Path First (FSPF) protocol is not affected by this vulnerability.

· Affected Products

Cisco devices that are running Cisco IOS Software and configured for OSPF are vulnerable. Devices that do not have OSPF enabled are not affected by this vulnerability.

Cisco devices that are running Cisco IOS Continue reading

UCS Central 1.1 Lab

I saw the announcement that Cisco had posted the emulator for UCS version 2.1(2a) a week ago. @CiscoServerGeek that integrates with UCS Central 1.1, right? — Frank Jimenez (@franjimecsco) July 26, 2013 This was pretty cool, seeing as the firmware version in general had only been out for a few weeks, and the emulators have traditionally taken a bit longer after their firmware release. I took this as an opportunity to set up my own UCS Central lab.

UCS Central 1.1 Lab

I saw the announcement that Cisco had posted the emulator for UCS version 2.1(2a) a week ago. @CiscoServerGeek that integrates with UCS Central 1.1, right? — Frank Jimenez (@franjimecsco) July 26, 2013 This was pretty cool, seeing as the firmware version in general had only been out for a few weeks, and the emulators have traditionally taken a bit longer after their firmware release. I took this as an opportunity to set up my own UCS Central lab.

Security Word of the Day: Stoogecraft

Today’s word of the day comes to Packetpushers courtesy of Seth Godin*: Stoogecraft. Stoogecraft is what happens when people or organizations in power do what feels right in the short run without thinking at all about the alternatives or the implications. It’s the result of fear or boredom or a misplaced focus. Sound familiar? Stoogecraft […]

Author information

Mrs. Y

Snarkitecht at Island of Misfit Toys

Mrs. Y is a recovering Unix engineer working in network security. Also the host of Healthy Paranoia and official nerd hunter. She likes long walks in hubsites, traveling to security conferences and spending time in the Bat Cave. Sincerely believes that every problem can be solved with a "for" loop. When not blogging or podcasting, can be found using up her 15 minutes in the Twittersphere or Google+ as @MrsYisWhy.
TwitterLinkedIn

The post Security Word of the Day: Stoogecraft appeared first on Packet Pushers Podcast and was written by Mrs. Y.

Nobody says it but we all feel like frauds

I am going to deviate a little bit from my normal career advice here and talk about something a bit more personal for me. I have told this story to colleagues at times over the past several years, and I am always a little surprised that everyone appears to feel the same way. But we […]

Author information

Michael Bushong

The post Nobody says it but we all feel like frauds appeared first on Packet Pushers Podcast and was written by Michael Bushong.

Teaching Without a Teaching Degree

So, let’s say you’re a technical admin, engineer, architect, whatever (most of you are). It’s probably safe to say that nearly all of you (I fit into this) have an occupation where our primary ongoing task is some combination of system or network administration, design, software and hardware engineering work, including build-out or troubleshooting, etc. Maybe it’s all of these. No matter what, it’s a safe assumption that a big, or maybe even number one reason we all get paid is because we’re really good at the technical work.
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