Subject: MPLS MIBs Related Questions

From: "Dinesh Mohan" <[email-masked]>
Date: Tue, 17 Oct 2000 17:25:48 -0400

I have recently started looking at MPLS Mibs. I have following
observations/questions on the following two MIBS:

1. MPLS TE MIB

 LSR1 ----> LSR2 -----> LSR4
      +                     +
        ----> LSR3 ------

A tunnel from Ip(lsr1) to Ip(lsr2) might have two path instances: [Ip(lsr1),
Ip(lsr2), Ip(lsr4)] and [Ip(lsr1), Ip(lsr3), Ip(lsr4)]
- should mplsTunnelTable on LSR2 have an entry for tunnel instance 1 and
LSR3 have an entry for tunnel instance 2?
- If yes, should LSR2 and LSR3 maintain mplsTunnelHopTable and
mplsTunnelARHopTable entries for these tunnel instances?
- Is it possible to indicate which tunnel instance is primary, secondary and
backup other than indicating different mplsTunnelInstancePriority values?
- If currently Instance 1 [lsr1, lsr2, lsr4] is active [adminStatus=up &
operStatus=up] and it goes down, is mplsTunnelDown expected from all three
nodes lsr1, lsr2 and lsr4?
- Also LSP now gets routed to Instance 2 [lsr1, lsr3, lsr4]. Does it mean
all three nodes should emit mplsTunnelUp traps?
- In above two scenarios, should mplsTunnelRerouted trap be genrated as
well? If yes, by which LSRs?

- in mplsTunnelSessionAttributes how is localProtectionAvailable value
different than fastReroute option?
- How is mplsTunnelLocalProtectInUse in mplsTunnelTable different than
mplsTunnelSessionAttribute's LocalProtectionAvailable value?
- MplsTunnelHopAddrType [ipv4, ipv6, asNumber or lspid]. This indicates the
next hop be IP, AsNumber or LSP-ID but 
  mplsOutSegmentNextHopType in mplsOutSegmentTable of MPLS LSR MIB?
- mplsTunnelARHopAddrType in mplsTunnelARHopTable has Ipv4, Ipv6 and
AsNumber as possible values. Why does it not include LspId value which is
specified for mplsTunnelHopAddrType?

- What does IsPinned value for mplsTunnelSessionAttribute indicate?
["indicates if the loosely-routed hops of this tunnel are to be pinned"]
- Are there any semantics associted to mplsXCLspId in mplsXCTable i.e. on
all LSRs would this ID would remain the same for cross-connection entries
for this tunnel instance? If yes, how is this achieved in manually
provisioned vs signalled setup of LSPs? Also does this value correspond in
any way to mplsTunnelName or instance in the MPLS TE Mib?

2. MPLS FTN MIB:

- FTN currently seem to support only IP over MPLS. How would it deal with
ATM over MPLS?
- FTN does not support mapping TOS bits in IP Header to LSPs i.e. how does
it support Diffserv?
- What is the difference between "redirect to LSP" vs "redirect to Tunnel"
in  mplsFTNAction object in mplsFTNTable?
- Question related to mplsFTNMapTable:
When mplsFTNMapIfIndex=0, the FTN is applicable to all interfaces. With the
following scenario:
  
  if1 ----|          |
          | LSR   |
  if2 ----|          |

If ftn1, ftn2, ftn3 and ftn4 are defined in mplsFTNTable with
mplsFTNIndex=1,2,3 & 4 respectively. And requirement is to apply ftn1 and
ftn2 on all interfaces but apply ftn3 on if1 in order ftn1, ftn2, ftn3 while
apply ftn4 on if2 in order ftn1, ftn4 and ftn2, the mplsFTNMapTable is
unable to capture this. entries for mplsFTNMapTable will be:
 
  mplsFTNMapIfIndex       0      0     if1   if2
  mplsFTNMapPrevIndex  0      ftn1  ftn2  ftn1
  mplsFTNMapCurrIndex  ftn1   ftn2  ftn3  ftn4

In this case either mplsFTNMapEntry [0, ftn1, ftn2] meets requirement for
if1but not for if2?

Dinesh Mohan