AS123456 EXAMPLE Peering Analysis Report

Introduction

This report is prepared from data captured on 14-Mar-2001 and therefore presents a snapshot of network connectivity & configuration.  It details the perspective view from various monitor points towards AS123456 through any AS(s) that announce AS123456.  While the raw data is taken from about a dozen different observation points across the Internet, the nature of BGP routing is such that each router in the Internet mesh only shares its best routes with its peers.  Consequentially, the quality of the raw data is dependant on the logical spread of observation points across the mesh.  We have yet to find evidence that this spread is insufficient.

The AS names have been drawn from ftp://rs.arin.net/netinfo/asn.txt and from as-name fields in IP Registries around the net.  A '?' is indicative of a missing as-name field in the relevant AS record.  In due course, we hope to improve the quality of this information.

Copyright: This report is published for sole use of the subscribing individual and all other rights are reserved.  Any unauthorized copying, sharing or resale is strictly prohibited and may lead to legal action.  This report is provided on the condition that it is not distributed in any way without proper license from NetConfigs.

The diagram below serves as a pictorial representation of the terms used in this report.

Transiting Peers

Transiting peers are those Autonomous Systems that announce AS123456 to one or more of their other peering relationships and potentially, therefore, to the rest of the Internet.

AS

Name

AS

Name

Direct Customer Peers

Direct customer peers are Autonomous Systems that have a direct peering relationship with AS123456 but are not transiting AS123456 to any of their other peers.  To be listed here, a route must be seen to traverse through a transit and then AS123456 before terminating in the relevant customer AS.  Possible reasons for missing entries are that during the period of data capture:

• The customer's peering relationship to AS123456 was inoperative.
• AS123456 was not advertising the peer to its transits.
• The transits of AS123456 were not accepting AS123456's advertisement of the peer.

AS

Name

AS

Name

Direct Customer/Transit Route-ability

This matrix shows which direct customer peers of AS123456 are being onward advertised by which transit peers.  Possible reasons for direct customers being listed while not having any transit routing are that during the period of data capture:

• The only observation points that could see the direct customer were direct peers of AS123456 which could not, in themselves, be considered as transit peers.

Routed Indirect Customer Peers

This table shows direct customers of direct customers of AS123456 where a route traverses one or more of AS123456's transits, then AS123456, then one or more of AS123456's direct customers and on to the indirect customer peer.

The number of levels of indirection is restricted one because the size of the table explodes beyond reasonable usefulness.

Non-Routed Indirect Customer Peers

This table lists direct customers of direct customers of AS123456 that are not routable via any of AS123456's transits through AS123456.  The AS numbers in brackets indicate which of AS123456's direct customers have a peering relationship with the indirect customer.  The presence of entries in this table may indicate customers of AS123456 that might be expecting a full transit service from AS123456 but are not receiving it.

57203(32072,38437)

Address Space Aggregate & Subnet Route-ability

This table is an ordered list of visible routes terminating in AS123456.  Aggregates are tagged with a leading '+' and subnets of the aggregates are tagged with a leading '-'.  The matrix shows which of AS123456's transit peers are onward announcing each address block.  Possibilities for further aggregation will be visible by virtue of the ordered-ness of the list.

Elimination of unnecessary subnets is good practice since each route causes a separate entry for each peering session on every BGP speaking router on the Internet.  Therefore, the existence of unnecessary routes demands excessive memory on each and every router in the Internet mesh.  A review of the 106,054 routes circulating the Internet, revealed an aggregate/subnet ratio of 41,576/64,478;  that is 61% of all routes are subnets.

It should be noted that subnets following the same routing as the associated aggregate serve no useful purpose.

Inconsistent AS's

This table is an ordered list of routes that are being advertised by AS123456 but which are also being advertised by other Autonomous System(s).  At this stage, inconsistent route announcements are only be listed if both the network and mask are matching.

A common cause of inconsistencies are mutual claims of ownership over exchange point address blocks.  Recognized best practice is that all address space should only ever be announced by the owning AS.

197.168.0.0/16(36872 123456) 220.21.0.0/19(42453 123456) 220.129.64.0/24(32914 46461 53701 123456) 221.106.0.0/17(44168 123456)