Telco question - Cisco LLF and loopback

Discussion in 'Hardware' started by skeeney, Jul 11, 2007.

  1. skeeney


    Jul 11, 2007
    Likes Received:
    Hi Guys,

    At work they have recently built a new completely private network for a major company, at the heart of the network are a series of cisco 6509 catalyst switches that serve remote sites dotted around the country. Each remote site has 2 x 10gbps links for resilience, traffic is muxed up and passed along various transmission devices and fibres until they are finally presented to a gigabit ethernet SFP module on our core 6509 switches.

    We have been advised that Link Loss Forwarding will be in place meaning that the physical link will drop in the event of a break further downstream.

    I would be grateful for any suggestions or answers to the below:

    - How does Link Loss Forwarding work? (Unfortunately unable to find any resources on this apart from product manuals). Could LLF be used to aid in localising faults when remotely applying loops on the transmission network? i.e. will the link restore when looped further downstream past the next point, or does LLF work by monitoring a layer 3 IP address?
    - Currently the network is in a build state however we would like to have the functionality as any of our other circuits where by we are able to place a loop on a b end customer mux and see the circuit restore and send data round it to check if any packet loss. Will this be possible?
    - On an enthernet link under a show interface, there is a line that states loopback not set, will the interface show as up looped when a loop is applied further downstream facing the 6509? Or will the link only show as up looped when a hard loopback is applied locally on the gigabit ethernet link?

    Bit of a long one I know but any help will be grately appreciated.

    skeeney, Jul 11, 2007
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