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Report of Meeting, 21st May 1997


Joachim Schmitz (JS395-RIPE)


Anne Lord (AL12-RIPE)



A. Preliminaries
Joachim Schmitz opened the working group and asked for a volunteer scribe. Anne Lord volunteered as scribe. There were 57 participants in the session.

The minutes of the last working group session had been previously circulated to the mailing list. These minutes were agreed as final and closed. A short overview of open actions was given.

Action 22.10 : J. Schmitz
Future tool development project - closed.
(was discussed during the working group meeting itself)
Action 25.R1 : D.Karrenberg
Route aggregation analysis - open.
Due to lack of time this has not been progressed. Volunteers to run scripts or do further development were asked for - they should contact Daniel Karrenberg. The present tool does slightly more than Tony Bates' aggregation report which looks at announcements being made. Daniel's tool actually emails originators with a "how to fix" mail.
Action 26.R1 : RIPE NCC
Add link to CIDR FAQ on RIPE web server - done.
Action 26.R2 : J. Schmitz
Trigger implementation of first elements of hierarchical authorisation for route objects - done.
Action 26.R3 : J. Schmitz
Finalise hierarchical authorisation for route objects - ongoing.
Action 26.R4 : E.J. Bos
Circulate URL of his analysis of routing table size - done.
Action 26.R5 : C. Panigl
Collect reasonable route flap dampening parameter values - done.
(was discussed during the working group meeting itself)

Current developments

Joachim reported briefly 2 working groups within the IETF that are relevant to the work of the Routing WG.

  • RPS - Routing Policy Systems

    Chairs are : Daniel Karrenberg and Cengiz Alaettinoglu
    http://www.ietf.o rg/html.charters/rps-charter.html

    The RPS working group wants to develop and propagate tools and methods to analyse and describe routing policies. One major project is RPSL "routing policy specification language". This is relevant for the Routing WG because they plan to switch from ripe-181 format for the routing registry to RPSL this year. The second version of an Internet draft on RPSL is already available.

  • RIDE - Registry Information Data Exchange

    Chairs are : David Kessens and Dhaval Shah

    This group is looking at ways of exchanging information between registries of all sorts in a unified "language". See URL for more information

B. Hierarchical Authorisation / Cross Notification of Route Objects in the IRR (Carol Orange)
1. Cross Notification
A draft proposal was sent to the Database and Routing WG mailing lists in May. The proposal is essentially to make network operators aware of overlapping route announcements in the IRR.

Implementation is by a new attribute in the route object called "x-notify". Using this attribute you will get notified if you submit a route object which overlaps an existing route object in the IRR or if another route object is submitted which overlaps your route object. Note - this will be an optional attribute.

The exact syntax is documented in the draft sent to the mailing list and can be found in the mailing list archives. There were also some additions from the Database WG.


It was envisaged that given the way that the current IRR is mirrored (once every 24 hours), there will be delay in notification. Real time mirroring would be ideal and the software exists. However this has not yet been fully implemented as this still requires input from other RR's. Gerald Winters from Merit (representing the RADB) commented that the current mirroring has been changed to mirror more frequently.

It was asked if there was a way to differentiate between exact matches and overlaps? It was commented that this could be built in to the software notification.

A question was then raised as to the exact notification that takes place when an overlap/exact match occurs and as to the timing of the possibilites for notifcation and to whom. Do you for example, also notify the originator of the overlap? Should the software return a warning to the originator of overlap even without the "x-notify" attribute ?

After a fairly lengthy and interesting discussion, it was agreed to go ahead with implementing the draft proposal given the following modifications which were agreed:

  • Whenever a route object is submitted in the RR, a notification should be generated to the submitter if the address space overlaps with any other route object in the RR. This is regardless of whether the new attribute for cross notification is used. Notification of overlaps can be built into the acceptance/feedback message returned to the submitter.
  • If the address space covered in the route object matched the address space in another route object, be sure this is clear in the notification message.
  • Notifications should be sent to the appropriate contact (and the submitter) not only if an overlap is introduced, but also when an overlap is elmininated.
  • for deleting a conflicting object, it was agreed to notify the submitter of the conflicting object that there was no longer a conflict in the database
  • notifications on overlap - either for newly submitted route objects, or for deletions - will only be done for existing route objects if explicitely requested by the "x-notify" attribute

Action 27.R1: Carol Orange, RIPE NCC
To implement cross notification in the RR with modifications as agreed at the meeting of the 27th RIPE Routing WG.
2. Hierarchical authorisation in the RR (Carol Orange)
(or "aut-num authorisation for route objects in the RR")
The proposal is documented in a draft document which was previously circulated to the Database WG and Routing WG mailing lists. Agreement on this proposal is now sought so that it can be implemented.

The goal of the proposal is to allow network operators who maintain an aut-num object ot determine who can submit/modify/delete a route object with their AS number as origin. There has been much discussion on the mailing lists and a specific "non-goal" of the proposal is to produce an optimal hierarchical authorisation scheme for the RR. This proposal is not CIDR based; hence the change of name for the draft to avoid any confusion about CIDR based hierarchy in the proposal to "Aut-num authorisation for route objects in the RR".

The proposal works briefly by the following mechanism:

A "mnt-route" attribute (in former drafts called "mnt-lower") is added to the aut-num object. With this addition the "mntner" object referenced determines through its authorisation definition who can add/update/delete an object associated with that aut-num (for more details see the draft which can be found at the reference in the archives of the mailing list).

The "mnt-route" attribute is optional and can be multiple per aut-num object. Each mnt-route attribute references it's own "mntner" object. This allows different people to maintain own routes announced.

Action 27.R2: Carol Orange, RIPE NCC
To implement aut-num authorisation in the RR

There was some discussion over the notification mechanisms when customers change their announcements in their AS - so as to enable notification to their upstream provider. This is actually a different issue and the discussion was deferred to the mailing list due to time constraints.
C. A future tool development project (Joachim Schmitz)
Joachim briefly described some of the existing tool sets in place to help network operators with their network operations and asked whether there was a need for such a new development effort in this area to be carried out under the auspices of RIPE and if so, where would it fit into the RIPE activity plan. Possibly, such a project could fit into the slot for "new activities" taken from the 1997 expenditures budget.

As background to this Joachim gave a description of the history (ish) and the functioning of the existing tools as well as the interaction with the relevant entities. ie. routers.. ISPs, IRR.... etc. Some of the tools he made mention of were the PRIDE tools eg. prtraceroute, prcheck, or the RATools eg. roe, aoe, peval, CIDR advisor...

The question was then asked: Is a new tool or software project needed ? What gaps exist in the existing toolsets?

It was felt generally by the audience that the orientation should be more towards actual integrity of the data in the RIPE database, quality and consistency of the DB rather than towards new tools.

Therefore, this action could be closed.

D. Report from the RIPE NCC
Time contraints prevented NCC from doing CIDR report and route aggregation analysis that had previously been started. However new technical projects are ongoing and they are going to hire more people to do technical projects.

The RIPE NCC welcomes any volunteers who wish to take over the production of the route aggregation analysis reports. Currently the reports are rather manually produced - mostly so in the generation of the "how to fix" emails which go out to the originators of "problems". Daniel repeated that he was quite willing to hand over the scripts if anyone wished to work on this since there are currently no human resources at the NCC at this point in time. There were no volunteers immediately.

It was agreed however that these reports were very useful and perhaps it would be possible to at least publish a summarised report and not send the "how to fix" emails. Reports will be sent out to the RIPE working group mailing list. Since Tony Bates' report on route aggregation also contains information on European ASs it was agreed to ask him whether a copy of his report is also distributed to the general RIPE mailing list.

Action 27.R3: RIPE NCC
To ask Tony Bates to send a copy of his regular CIDR report to the general RIPE mailing list as well.
E. Route Flap Dampening Parameters (Christian Panigl)

C. Panigl started with a summary of the BOF at the last RIPE meeting. Consensus was that we needed route flap dampening, but there was no consensus on dampening parameters: 2 camps had previously emerged:

  • Those in favour of "progressive" dampening with the exclusion of "golden" networks ie. root name servers.
  • or "flat and gentle" where all prefixes are treated equally a la Cisco default dampening.

As an action from the previous Routing WG meeting, Christian Panigl presented information he had collected about dampening parameters. As a basis for his studies, he took information about dampening parameters from the following sources:

  • discussions by Randy Bush a la SPRINT/ICM parameters
  • Tony Barbers presentation on progressive route flap dampening at UUnet PIPEX

Christian reported on the work by Sean Donelan who made investigations comparing /24 prefixes and /16 prefixes:

/24: 65% of Routing Table accounts for 65% of all route flaps
/16: 12% of Routing Table accounts for 10% of all route flaps

Both groups tend to flap ~2% of the routes within the group.

What is the goal of flap dampening: stable routes or shorter prefixes? It was suggested that softer "punishment" of shorter prefixes might lead to future waste of address space.

Some router cpu offload has happened with progressive dampening. Excessive BGP withdrawal problem seems to be fixed in IOS 11.1(8) for Cisco routers.

The assumption that the /24 is more unstable is not necessarily true given the following situation:


reload after s/w uprade

- 1x flap

new s/w crashes

- 1x flap

reload with old s/w

- 1x flap=3x flaps within 10 min utes

Then according to Randy's parameters /24 prefixes were blocked for 3.5 hours, /22 45 minutes, /19 45 minutes, /16 less than 30 minutes. According to Tony's paramters /24 prefixes were blocked for 2hrs 45mins, /22 55 minutes, /19 55 minutes /16 less than 30 minutes.

It was suggested that suppression should not start until the 4th flap in a row which corresponds to parameter value suppress=3000 and that the maximum suppression should not last longer than 1hour (max supress <60).

At the meeting there was consensus that it is beneficial if everyone adopts the same parameters, because it allows problems to be detected and addressed on the home front.

It was agreed that a recommendation from RIPE would be desirable. Given that the current allocation policies are expected to hold for the foreseeable future, it was suggested that all /19's or shorter prefixes are not penalised outside of the Cisco default dampening.

Action 27.R4: Task Force (Tony Barber, Sean Doran, Daniel Karrenberg and Christian Panigl).
To write proposal document and circulate to the RIPE rounting working group mailing list for discussion as soon as possible.
F. Reports from other WGs
There was no current input from other WGs.
Since there was no AOB the meeting was closed.


- Routing Working Group Meeting -

Agenda for RIPE-27, May 1997, Dublin

A. Preliminaries
  • introduction
  • participants' list
  • volunteering of scribe
  • agenda bashing
  • RIPE 26 minutes
  • actions from earlier meetings
  • current developments
B. Hierarchical Authorisation/Notification of Route Objects
  • first implementation issues (Carol Orange)
  • further developments (Joachim Schmitz)
  • discussion
C. A Future Tool Development Project (Joachim Schmitz)
  • an overview
  • discussion
D. Report from the RIPE NCC (Daniel Karrenberg)
E. Route Flap Dampening Parameters (Christian Panigl)
  • overview
  • suggested parameters
Y. General Input from Other WGs

Summary of Actions:

Action 25.R1: D.Karrenberg
To report on the results from the route aggregation analysis on the next RIPE meeting
Action 26.R3: J. Schmitz
To finalize the hierarchical authorization for route objects together with the Routing WG
Action 27.R1: Carol Orange, RIPE NCC
To implement cross notification in the RR with modifications as agreed at the meeting of the 27th RIPE Routing WG.
Action 27.R2: Carol Orange, RIPE NCC
To implement aut-num authorisation in the RR
Action 27.R3: RIPE NCC
To ask Tony Bates to send a copy of his regular CIDR report to the general RIPE mailing list as well.
Action 27.R4: Task Force (Tony Barber, Sean Doran, Daniel Karrenberg and Christian Panigl).
To write proposal document and circulate to the RIPE Routing WG mailing list for discussion as soon as possible.

Anne Lord, Joachim Schmitz