Articles in the networking category

  1. Cisco IPS Inline Bypass Mode

    Posted on in Networking

    On occasion, you may need to put your Cisco IPS into bypass mode. Bypass mode allows the IPS to pass traffic without inspecting it. This may be useful if you suspect the IPS is causing a problem, if you are going to run a one-time scan that would set the …

  2. Enabling Stateful Switchover in the Cisco ASR1000

    Posted on in Networking

    When you get your brand new Cisco ASR1000 series router, Stateful Switchover (SSO) is disabled by default:

    Router# show redundancy states
           my state = 13 -ACTIVE 
         peer state = 1  -DISABLED 
               Mode = Simplex
            Unit ID = 6
    Redundancy Mode (Operational) = Non-redundant
    Redundancy Mode (Configured)  = Non-redundant
    Redundancy State              = Non Redundant
    

    Enable SSO!

    Router# config …
  3. What are BGP Update-Groups?

    Posted on in Networking

    You've certainly noticed when look at individual BGP routes on your Cisco routers that the route is advertised to specific update-groups. It isn't obvious from that output just what those update-groups are.

    Router#show ip bgp 8.8.8.8       
    BGP routing table entry for 8.8.8.0/24 …
  4. Cisco Catalyst NVRAM Corruption

    Posted on in Networking

    This is an annoying problem:

    Switch#write
    startup-config file open failed (Not enough space)
    
    Switch#dir nvram:
    Directory of nvram:/
    
    %Error opening nvram:/ (Function not implemented)
    
    1048576 bytes total (1034573 bytes free)
    

    Cisco Catalyst switches simulate NVRAM on their flash. Once in a blue moon, this simulated NVRAM will become …

  5. QM FSM Error? Check Your Transform-Set

    Posted on in Networking

    If you see an error like the one below in your Cisco ASA log files, check with the other end and make sure your transform-set matches.

    QM FSM error (P2 struct &0xd7fed708, mess id 0xcc86fb64)!
    

    The QM FSM error message usually relates to a configuration mismatch. Although checking the crypto …

  6. Alternative to 'show policy-map interface' on Catalyst Switches

    Posted on in Networking

    Old Cisco Systems LogoIf you're using policy-maps on your Cisco Catalyst switches to handle rate-limiting, you may have noticed that on some models, the show policy-map interface command does not seem to work. The CLI accepts the command and returns properly formatted output, but the output is all zeroes. There is no information …

  7. Brand New ME3400G Can't Ping!

    Posted on in Networking

    Old Cisco Systems LogoAfter cracking open a brand new Catalyst ME3400G, we weren't able to get it upgraded to the latest version of software. In fact, we couldn't even ping anything on the local subnet.

    In order to use Cisco's Metro Ethernet switches, it's important to understand the new concepts that are introduced …

  8. Does load-interval Affect Performance?

    Posted on in Networking

    I was recently part of a discussion regarding whether or not lowering the load-interval on a Cisco router or switch interface from the default of 300 seconds had an impact on performance. Both sides made good points, but both were based on assumption and conjecture.

    5 minute input rate 213000 …
  9. Cisco: Time-based, Inbound Rate Limiting

    Posted on in Networking

    Slaptijack reader Raj is looking for a way to limit inbound traffic on his switch ports based on the time of day. Specifically, he wants to restrict speed to 256 Kbps between 9 AM and 9 PM, and allow up to 1 Mbps the rest of the day. I've done …

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