Well Known Intervals

planet-oceanListed below are many events which occur on network devices at well-known intervals. The list is provided to serve as an aid while troubleshooting recurring network disruptions. Please consider helping to expand this list by adding other recurrent issues you encounter not already listed.

This list was generated by Jeremy Stretch from PacketLife, but lost after he took his wiki down. Luckily I had previously saved it, as I found it useful, and with his permission I’ve reposted it here.

Short (<=5 minutes)

1 Second

  • Default VRRP hello timer
  • Default EAP-Identity-Request Timeout (Unified WLAN)
  • Default EAP-Request Timeout (Unified WLAN)
  • Default EAPOL-KEY Timeout (Unified WLAN)
  • CleanAir AP Sampling Interval (Unified WLAN)
  • Default Group Specific Query interval (Maximum Response Time of 10) for IGMPv2

2 Seconds

  • Default IEEE 802.1D STP hello timer
  • Default RADIUS / LDAP Server Timeout (Unified & Autonomous WLAN)
  • Default NMSP Updates from WLC to Loc/MSE Server (Unified WLAN)
  • Default IGMPv2 Last Member Query Count x 2

3 Seconds

  • Default GLBP hello timer (Cisco IOS)
  • Default HSRP hello timer (Cisco IOS)

5 Seconds

  • Default EIGRP hello timer on links >= 1.544 Mbps (Cisco IOS)
  • Default LDP hello timer for links (Cisco IOS)

10 Seconds

  • Default HSRP hold timer (Cisco IOS)
  • Default IS-IS hello timer (Cisco IOS)
  • Default OSPF hello timer on broadcast and point-to-point links (Cisco IOS/JunOS)
  • Default 802.1x Supplicant Response Timeout (Unified WLAN)
  • Default Mobility Keepalive Interval (Unified WLAN)
  • Default AP Discovery Timeout (Unified WLAN)
  • Default LDP hello timer for targeted LDP (Cisco IOS)
  • Default LMI Frame Relay message
  • Default IGMPv2 Query Response Interval

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FCC approves net neutrality rules, reclassifies broadband as a utility

Net NeutralityToday is a good day. By a 3-2 vote, the FCC has voted to adopt net neutrality rules to protect the open Internet. This plan will reclassify internet access as a Title II public utility, which in turn gives the agency more regulatory power. While many will say that any power grab by the government is a bad thing, this is certainly good news for consumers. The Internet as a whole has become far too important to be controlled by a few private corporations which are more interested in lining their own pockets rather than listening to public interest. FCC Chairman Tom Wheeler was quoted saying, “This is no more a plan to regulate the Internet than the First Amendment is a plan to regulate free speech.” I couldn’t of said it any better myself.

This plan will put a stop to paid prioritization (see Comcast / Verizon forcing Netflix to pay for bandwidth usage, which is the complete opposite of most peering agreements. ) — It also prevents ISPs from creating Internet slow lanes for traffic as they see fit. Until now, Verizon wireless has been allowed to charge it’s customers monthly fees for access to “business email” when using services such as Good for Enterprise, or Blackberry.

While this is fantastic news, no one expects the drama to end here. Verizon has made vague threats about suing the FCC, and I can imagine other providers will also push this into an appeals court. Hopefully, nothing will prevent the FCC from classifying Internet service as a Title II utility, which was the missing piece from the FCC’s first effort to draft open Internet rules, which were eventually struck down in court thanks to Verizon.

The full FCC order will be available on the commission’s website within the next few weeks, and the order will take effect 60 days after being published.

Cisco Live 2015 – Mike Rowe Announced as Keynote Speaker

mike-rowe-life-adviceCisco just announced to the Cisco Champion community that the guest speaker for the keynote is going to be none other than …… Mike Rowe!! In case you don’t know, Mike Rowe is an American TV host, narrator, actor, and former opera singer. He is best-known for his extensive work on the Discovery Channel. He has starred on the shows Dirty Jobs, and narrated many shows including Deadliest Catch, American Hot Rod, and Ghost Hunters. He also did a quick stint on the QVC Shopping Network where he was hired after talking about a pencil for nearly eight minutes. According to his bio,  he worked the graveyard shift for just three years, until he was ultimately fired for making fun of products and belittling viewers. I’ve included one of my favorite videos from his time at QVC down below, be sure to check out some of the other ones if you haven’t seen them.

Mike also founded the mikeroweWORKS Foundation, which promotes hard work. Mike has long been a supporter of the skilled trades and his foundation works hard at awarding scholarships to men and women who demonstrate an aptitude for doing the work that America needs. He is also closely associated with the Future Farmers of America, Skills USA, and the Boy Scouts of America, who honored him as a Distinguished Eagle Scout. And Forbes has identified him as one of the country’s 10 Most Trustworthy Celebrities in 2010, 2011 and 2012.

I am so excited about this years event. Aerosmith? Mike Rowe? What’s going to be next!? If you want to hear Mike speak, you have to come to Cisco Live. So if you haven’t already registered for CLUS15,  it’s not too late, so do it NOW!!!

Oh, and it seems that Jeff finally got his wish… and it only took 4 years =)

2015-02-13 at 11.29 PM

BGP Communities

bgp2-internetBGP Communities has to be one of my favorite features added to the BGP protocol.  As you should know by now, BGP passes several attributes between peers that help influence the BGP best path selection algorithm. One of these is the BGP Community attribute. Think of this as another tag placed on the route advertisement that can give us additional information.

This tag is formatted as 32bit value that is typically displayed in two 16 bit parts. The most typical, and most widely accepted best practices treat these as your Autonomous System Number (ASN), followed by a 16 bit attribute. For example, if your ASN was 65248 and you wanted to tag this route with the number 666, you would set something like 65248:666.

As for the second half of our tag, this number is arbitrary. BGP Communities are a transitive attribute that is completely optional. This means that BGP treats these tags as purely information, and that it is up to the network engineer to decide what these values mean, and what to do with them.

RFC 1997 defines some well known communities that have global significance. These values and their operations should be respected by any community aware BGP implementation. The RFC also reserves the values 0x00000000 through 0x0000FFFF and 0xFFFF0000 through 0xFFFFFFFF, but only a few of those values have been implemented. For more information, see IANA’s Page.

  • NO_EXPORT (0xFFFFFF01) – All routes received carrying a communities attribute containing this value MUST NOT be advertised outside a BGP confederation boundary (a stand-alone autonomous system that is not part of a confederation should be considered a confederation itself).
  • NO_ADVERTISE (0xFFFFFF02) – All routes received carrying a communities attribute containing this value MUST NOT be advertised to other BGP peers.
  • NO_EXPORT_SUBCONFED (0x0xFFFFFF03) – All routes received carrying a communities attribute containing this value MUST NOT be advertised to external BGP peers (this includes peers in other members autonomous systems inside a BGP confederation).
  • NOPEER (0xFFFFFF04) – Introduced much later in RFC 3765 and not currently recognized by all vendors. This community is used to limit advertisements to bi-lateral peers.

By default Cisco IOS does not propagate BGP communities. You must manually configure each neighbor with the neighbor send-community command.

As for the “public” community space, your imagination is the limit. Depending on the complexity of the network any number of things could be represented by the community strings attached. Personally, I typically use them to mark information about the routes, such as peer information or changes to the local-preference made on the edge network. But the most useful thing is using them to influence other attributes. You can even allow customers to influence routes they advertise to you, which is especially helpful when a customer connects to your network in multiple locations that advertise some of the same routes. For example, in your public community list you could allow your customers to advertise you a route with 65248:80, or 65248:120 which you could then match in your neighbor route-map in to set the local preference to either 80, or 120 on that specific route. Other options could set prepending, or…

Remote Triggered Blackholes (RTBH) allows a customer to advertise a single host (/32) to your network with a community string designating that you should “black hole” that traffic. This is particularly helpful in the event of a DOS/DDOS. The black hole’d host no longer receives traffic, as it is stopped on the upstream network. Which, as long as the upstream pipes are big enough, can allow the rest of the downstream network to still function.

A more recent upgrade to “standard” BGP Communities is the extended community attribute defined in RFC 4360. Since the use of BGP Communities became so popular with the ever expanding world of MPLS and VPLS VPN tunnels, the community values were quickly overrun and needed expansion. The extended community attribute is an 8 octet value which is double our original 32bit field.

Extended communities provide a number of benefits to service provider networks, most of which are out of scope for this current post. But I will point you here, if you want to learn more about the use of extended communities with route targets in both IOS and Junos.

Cisco Live 2015 – Customer Appreciation Event Featuring Aerosmith!!

Yes, you heard me right. Aerosmith!

Aero - new version LOGO copy
One of the most looked forward to social events for Cisco Live has always been the Customer Appreciation Events (CAE). Cisco rarely let’s us down when throwing this shindig, and has amazed us in the past with renting out resorts, baseball stadiums, and even Universal Studios.

This year, the CAE will be held on Wednesday June 10th at 7:30 inside Petco Park which is just a short walk from the convention center. With Aerosmith headlining this event it is sure to be huge! So if you haven’t already registered for CLUS15, be sure to do so NOW!!!

Petco-Park-Photo1000x1000 (3)

In other news, it seems that CDW is sponsering a new outdoor social media area for us to connect and hang out by the waterfront. Currently I believe this to be in addition to the normal social media hub that Cisco has been providing us since 2012.


This rendering of the area seems to indicate that it is located behind the convention center, probably in this area…

2015-02-06 at 9.03 PM

If you have any questions about this years event please reach out to @CiscoLive on twitter, or on Facebook!

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