[ipxe-devel] Adding lldp-agent to ipxe

Anton D. Kachalov mouse at yandex-team.ru
Mon Jun 16 08:17:49 UTC 2014


Did someone start to implement LLDP/CDP support?

25.09.2013, 18:46, "Michael Brown" <mbrown at fensystems.co.uk>:
> On 12/09/13 11:05, Thomas Mieslinger wrote:
>>  [...]
>>  It would be helpful for that overview page if I could display the
>>  switchport right away.
>>  So for me, I'd just need PortID and PortDescr. But for other uses, I
>>  guess that ChassisID, SysName and SysDescr could be useful.
>>  For naming ipxe variables, I'd propose the trick to compose the name of
>>  a prefix and the original variable name. Example: lldp-PortDescr which
>>  then would be used as ${net0/lldp-PortID:uristring}.
>>  Ok, so the next step would be wait for the approval of the variable
>>  names and then to propose a patch.
>  From a quick look at the LLDP specs, it seems as though the mapping
>    ${net0.lldp/<length>.<offset>.<type>}
> might be reasonably natural, where <type> is the LLDP TLV type, and
> <offset> and <length> describe the offset and length of the desired data
> within the TLV value.  (As a special case, a <length> of zero could
> indicate "all remaining data".)
> This would allow for some fairly simple encodings of simple values, e.g.
>    ${net0.lldp/4:string} for the Port Description
>    ${net0.lldp/5:string} for the System Name
>    ${net0.lldp/3:uint16} for the Time To Live
> while also allowing for access to the more complex LLDP data structures
>    ${net0.lldp/1.0.1:uint8} for the Chassis ID Subtype
>    ${net0.lldp/1.1:hex} for the Chassis ID
> There seems to be no way to solicit LLDP information; iPXE would just
> have to wait for an LLDP packet to arrive.  This wait could be
> implemented within an iPXE script, e.g.:
>    ifopen
>    :lldp
>    isset ${net0.lldp/1} && goto lldp_done
>    sleep 1
>    goto lldp
>    :lldp_done
> I'm assuming that we need to support only point-to-point LANs, and that
> we can get away with receive-only operation (i.e. no need to transmit
> our own LLDP information).
> Michael
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Anton D. Kachalov

ITO, System Architect
Tel: 7 (495) 739-70-00 ext.7613

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