Re: MAC Address As Index

On Tue, Sep 3, 2019 at 5:23 PM Krishna Chaitanya
<[email protected]> wrote:
>
> On Tue, Aug 27, 2019 at 2:12 PM Krishna Chaitanya
> <[email protected]> wrote:
> >
> > On Mon, Aug 26, 2019 at 9:22 PM Bill Fenner <[email protected]> wrote:
> > >
> > > On Tue, Aug 20, 2019 at 8:45 AM Krishna Chaitanya <[email protected]> wrote:
> > >>
> > >> Hi,
> > >>
> > >> When using MAC Address as an index ( I am using MacAddress type from
> > >> SNMPv2-TC.) the output is incorrect because the length of the string
> > >> is prefixed as mac address is defined as OCTET STR there is an extra
> > >> byte and the last byte of mac address is interpreted as next OID.
> > >>
> > >> snmpwalk:
> > >>    HistValue."wlp8s0f0".'....B.'.hist_2.2.19
> > >> snmpwalk -OX
> > >>   HistValue["wlp8s0f0"][STRING: 06:00:90:e6:42:99][hist_2][2].19
> > >>
> > >> In the above examples last but one OID 2 is hist_2. Is there a way to
> > >> disable prefixing of length?
> > >
> > >
> > > The prefixing of length is done by the agent.  Are you asking about a MIB module that you implemented?  Try changing your object definition from ASN_OCTET_STR to ASN_PRIV_IMPLIED_OCTET_STR.
> > Yes, I am using my own MIB and changing to ASN_PRIV_IMPLIED_OCTET_STR
> > in the subagent worked.
> > Thanks, Bill.
>
> After this change, I was getting a lot of duplicate data exists
> errors, upon further debugging found a similar issue
> which is quite old
> https://www.mail-archive.com/[email protected]/msg06286.html.
> In the current code even though there is support to handle IMPLIED
> strings, but subsequent indexes are not processed.
> See snippet below: out of 4 indexes only 2 are processed (the indexes
> after ASN_PRIV_IMPLIED_OCTET_STR
> failed to parse. Any ideas?
>
> histStatsData: Request Mode is: 160 name: wlp8s0f0 col: 3
> histStatsData: Add row
> duplicate table data attempted to be entered. row exists
> helper:table:req: Got GETNEXT (161) mode request for handler table:
> base oid:SNMPv2-SMI::mib-2.43932.2.2
> helper:table:col:   have at least a column (3)
> helper:table:     have 17 bytes of index
> helper:table:   looking for 4 indexes
>
> parse_oid_indexes: Parsed str(4): wlp8s0f0
> helper:table:   got 1 (incomplete=0)
>
> parse_oid_indexes: Parsed str(196):
> helper:table:   got 1 (incomplete=0)
>
> helper:table:   oid indexes not complete:
> SNMPv2-SMI::mib-2.43932.2.2.1.3.8.119.108.112.56.115.48.102.48.0.128.225.66.153.1.2.15
> helper:table:results:   found 2 indexes
> helper:table:results:   column: 3, indexes: 2   index: type=4(04),
> value=STRING: "wlp8s0f0"   index: type=196(c4), value=Variable has bad
> type
>

As a workaround moved the MAC address index to last and it works fine
with ASN_IMPLIED_OCTER_STR, this should be good enough for parsing
programmatically, but
for end-user its a bit counter-intuitive, having MAC Address as the
2nd index out of 4 is
more readable. This was the diff in MIB:

-  INDEX { ifaceName, remoteMAC, HistClass, HistBinIndex}
+  INDEX { ifaceName, HistClass, HistBinIndex, remoteMAC}