Hi. As you all know, the concept of Home AS is central to the expression of AS policies in RIPE-181 and the Global Routing Registry. The NSFNET Policy Routing Database (PRDB) has been collecting Home AS values for a year now, though those values have not been required for AS690 routing. As part of the transition from the to the Routing Arbiter Database and the Global Routing Registry (RADB/GRR), we are in the process of updating the database Home AS information. There are three steps to the plan to update this information: 1) On November 1st, some missing Home AS values were filled in from AS-path information from BGP sessions with origin "IGP". (RIPE database values were also used to update Home AS values for European nets in the PRDB). A report on Home AS (and related) values before this was done is contained in the file nic.merit.edu:nsfnet/announced.networks/home_as.Nov_1_1994 . This operation updated 1592 Home As values, and corrected the Home AS values for 365 European nets. Unfortunately, it still left PRDB 7,227 nets without Home As values. 2) Between now and November 25, we encourage all NSPs to determine the Home ASs for nets that they originate or route, and to send that information to nsfnet-admin@merit.edu. (Just send net lists and ASs; don't bother with NACRs for this process). 3) On November 25, we will update any remaining missing Home AS values using the following algorithm for each net: - If BGP paths have origin "IGP" and show only a single value for the end (Home) AS, use that AS. - Else if BGP paths have origin "IGP" and show multiple values for the end (Home) AS, use one of those ASs. - Else if BGP paths have origin "EGP", use that AS. - Else if BGP paths have origin "INCOMPLETE", use that AS. - Else use the primary announcing AS from the AS690 Metric:AS list. To see what this algorithm would do to your nets if we ran it today, look at the file nic.merit.edu:nsfnet/announced.networks/home_as.now :
IP/len Net Name AS Src (IGP) ----- Metric:AS(NSS) List ---- ---------- ----------- ---- --- ---- ------------------------------ 6/8 YPG-NET 19 INC - 1:568 2:19 7/8 EDN-TEMP 35 now - 1:701(136) 2:701(134) 8/8 BBNCCNET 560 INC - 1:560 2:701(136) 3:701(134) 13/8 XEROX-NET 200 now - 1:200(128) 2:200(144) 15/8 HP-INTERNET 71 now - 1:200(128) 2:200(144) 3:2149 4:174 16/8 DEC-INTERNET 33 now - 1:200(128) 2:200(144) 3:701(136) 4 17/8 APPLE-WWNET 714 now - 1:200(128) 2:200(144) 3:1740 18/8 MIT 3 now - 1:3 2:560 3:701(136) 4:701(134) 20/8 CSC 701 now - 1:701(136) 2:701(134) 26/8 MILNET 19 now 568 1:568 2:19 28/8 WIDEBAND 2699 EGP - 1:2699(145) 2:2699(144) 29/8 MILX25-TEMP 19 PRI - 1:19 2:568 31/8 UCDLA-NET 1740 PRI - 1:1740 2:200(128) 3:200(144) 4:195 32/8 NORGESNETT 2120 now - 1:1800 2:1879 3:1133 4:1240 33/8 DCMC 19 INC - 1:19 2:568 34/8 HALLIBURTON 1328 INC - 1:1328 35/8 MERIT 237 now - 1:237 2:233 3:266 4:267 5:1225 36/8 SU-NET-TEMP 32 now - 1:200(128) 2:200(144) 38/8 PSINETA 174 now MULT 1:2149 2:174 40/8 LILLY-NET 17 now - 1:17 ..
The "AS" column shows the AS that the algorithm will choose if the net is not otherwise updated by November 25. The "Src" column shows the reason for that value: "now" means there is a current PRDB Home AS value, "EPG", "INC", and "PRI" indicate that an AS path "EGP" or "Incomplete" value would be used, or that the Primary announcing AS would be used. The "(IGP)" column show were AS path "IGP" values show a different Home AS than the one registered in the PRDB. "MULT" in this column indicates that our BGP dump showed multiple AS paths were specifying different IGP ASs were concurrently being announced for this net. A more complete explantion of the columns is indcluded at the head of the report file. The report format is designed for easy grep'ing: grep for ' 237 ' to find all nets relevant to AS237, or for ' :237 ' to find all nets with AS237 somewhere in the Metric:AS list. --Dale Johnson