Transcript Using RPSL in Practice - University of Massachusetts Amherst

Using RPSL in Practice
Chun Zhang
Nov 2, 2000
1
ECE 697F: Special Topics - Internet Routing
Introduction



Terminology
How to specify routing policies?
How to analyze routing policies?
2
Terminology - RPSL

Routing Policy Specification Language
RIPE181 - RFC 1786 (March 1995)
RPSL - RFC 2280 (June 1999)
Specify much wider range routing policy
3
Terminology - IRR

Internet Routing Registry

Repository of routing policies
4
Terminology - IRR (Cont.)
Evolution Of IRR

1995, Originally 5 databases
CA*NET (now Bell Canada)
[Canada]
RADB, CW, ANS(now UUnet) [US]
RIPE
[Europe]

Now, more than two dozen databases
5
Filters
Routes
Routes
Criteria
6
Filters Type

Destination address-prefix
– {128.9.0.0/16, 128.8.0.0/16}
– AS2 == {128.9.0.0/16, 128.8.0.0/16}
AS2
128.9.0.0/16
128.8.0.0/16
– AS-FOO == {AS1, AS2, AS3}
7
Filters Type

AS Path
?? What does this mean ??
– <^AS1.*AS2$>
– <^AS1[AS2 AS3 AS4] *$>
8
AS Path Regular Expressions




^ matches empty string at the
beginning of AS path
. match any AS number
$ matches the empty string at the
end of an AS path
[…] matches any element in the AS
set
9
AS Path Regular Expressions

Zero or more occurrences A*
A

One or more occurrences
A+
A

Zero or one occurrences
A?
A
10
AS Path Regular Expressions

Binary concatenation operator:
– Example : AB
A

B
Binary alternative (or) operator: |
– Example : A|B
A
B
11
Regular Expressions Examples

<^AS1.*AS2$>
Start

AS1
AS2
End
<^AS1[AS2 AS3 AS4] *$>
A2
Start
AS1
A3
End
A4
12
Filters Type
Other routes attributes
Example : Community attributes

Optional transitive attribute of variable length
(a list of 4-byte integers)
4-byte integer
4-byte integer
4-byte integer
4-byte integer
4-byte integer
4-byte integer
AS1
AS2
100
100
AS3
100
13
Autonomous system object
Aut-num:
as-name:
descr:
import:
export:
admin-c:
tech-c:
mnt-by:
changed:
source:
AS2
CAT-NET
Catatonic State University
from AS1 accept ANY
to AS3 announce ANY
AO36-RIPE
CO19-RIPE
OPS4-RIPE
[email protected]
RIPE
14
Specify Policy in RPSL(I)
Common Peering Policies
Aut-num:
import:
import:
export:
export:
AS1
peer
AS2
from AS1 accept ANY
from AS3 accept <^AS3+$>
to AS3 announce ANY
to AS1 announce AS2, AS3
AS2
AS3
customer
15
Specify Policy in RPSL(II)
ISP Customer - Transit Provider Policies
Aut-num:
AS2
import:
from AS1 accept ANY
import:
from AS3 accept <^AS3+$>
import:
from AS4 accept <^AS4+$>
export:
to AS3 announce ANY
export:
to AS4 announce ANY
export:
to AS1 announce AS2, AS3, AS4
AS1
AS2 peer
AS2
AS3
AS2 customer
AS4 Another AS2 customer
16
Specify Policy in RPSL(II)
Using as-set object for simplification
as-set:
members:
Aut-num:
import:
import:
export:
export:
AS2:AS-CUSTOMERS
AS3 AS4
AS2
from AS1 accept ANY
from AS2:AS-CUSTOMERS accept
<^AS2:AS-CUSTOMERS+$>
to AS2:AS-CUSTOMERS announce ANY
to AS1 announce AS2 AS2:AS-CUSTOMERS
17
Specify Policy in RPSL(II)
Using route-set object for simplification
Aut-num:
import:
import:
import:
export:
export:
AS2
from AS1 accept ANY
from AS3 accept {7.7.0.0/16^16-19}
from AS4 accept {7.8.0.0/16^16-18}
to AS2:AS-CUSTOMERS announce ANY
to AS1 announce AS2, AS2:AS-CUSTOMERS
18
Specify Policy in RPSL(II)
Using route-set object for simplification
route-set:
members:
AS2:RS-ROUTES:AS3
{7.7.0.0/16^16-19}
route-set:
members:
AS2:RS-ROUTES:AS4
{7.8.0.0/16^16-18}
19
Specify Policy in RPSL(II)
Using route-set object for simplification
Aut-num:
import:
import:
import:
export:
export:
AS2
from AS1 accept ANY
from AS3 accept AS2:RS-ROUTES:AS3
from AS4 accept AS2:RS-ROUTES:AS4
to AS2:AS-CUSTOMERS announce ANY
to AS1 announce AS2, AS2:AS-CUSTOMERS
20
Specify Policy in RPSL(II)
Using route-set object for simplification
Aut-num:
import:
import:
import:
export:
export:
AS2
from AS1 accept ANY
from AS3 accept AS2:RS-ROUTES:PeerAS
from AS4 accept AS2:RS-ROUTES:PeerAS
to AS2:AS-CUSTOMERS announce ANY
to AS1 announce AS2, AS2:AS-CUSTOMERS
21
Specify Policy in RPSL(II)
Using route-set object for simplification
Aut-num:
import:
import:
export:
export:
AS2
from AS1 accept ANY
from AS2:AS-CUSTOMERS accept
AS2:RS-ROUTES:PeerAS
to AS2:AS-CUSTOMERS announce ANY
to AS1 announce AS2, AS2:AS-CUSTOMERS
22
Specify Policy in RPSL(III)
Including Interfaces in Peering Definitions
aut-num:
import:
AS1
from AS2 7.7.7.2 at 7.7.7.1
accept <^AS2+$>
7.7.7.1
7.7.7.2
AS1
AS2
7.7.7.3
23
Specify Policy in RPSL(IV)
Describing Simple Backup Connections
7.7.7.1
7.7.7.2
AS1
AS2
7.7.7.3
aut-num:
import:
AS1
from AS2 7.7.7.2 at 7.7.7.1 action pref=10;
from AS2 7.7.7.3 at 7.7.7.1 action pref=20;
accept <^AS2+$>
higher the number, lower the preference !!!
aut-num:
AS2
export:
to AS1 7.7.7.1 at 7.7.7.2 action med=10;
to AS1 7.7.7.1 at 7.7.7.3 action med=20;
announce <^AS2+$>
24
Specify Policy in RPSL(V)
Multi-home Routing Policies using the community Attribute
I
AS2
AS1 II
AS4
AS3
??? How AS4 signal AS1 to select path I/II ???
Solution: Using route community attributes
aut-num:AS1
import: from AS2 accept (AS2 OR AS4) and <^AS2+ AS4*$>
import: from AS3 accept (AS3 OR AS4) and <^AS3+ AS4*$>
import: from AS5 accept AS5 and <^AS5+$>
25
Specify Policy in RPSL(V)
Multi-home Routing Policies using the community Attribute



AS1: I prefer the path where
community attribute = C
AS4: Ok! Let me set my favorite path’s
community attribute = C
AS1: Yes! Attribute = C
I am working as you like!
26
AS1: I prefer where community=C
Aut-num: AS1
import: from AS2 action pref=10; accept (AS2 OR AS4) AND
<^AS2+AS4*$> AND commnuity.contains(1:1)
import: from AS2 action pref=0; accept(AS2 OR AS4) AND
<^AS2+AS4*$>
import: from AS3 action pref=10; accept (AS3 OR AS4) AND
<^AS2+AS4*$> AND commnuity.contains(1:1)
import: from AS3 action pref=0; accept(AS3 OR AS4) AND
<^AS2+AS4*$>
27
AS1: I prefer where community=C
Using refine for simplification
Aut-num: AS1
import: {
from AS-ANY
action pref=10;
accept community.contains(1:1);
from AS-ANY
action pref=0;
accept ANY;
} refine {
from AS2 accept (AS2 OR AS4) AND <^AS2+AS4*$> ;
from AS3 accept (AS3 OR AS4) AND <^AS3+AS4*$> ;
}
28
AS4: Let me set my favorite
Aut-num: AS4
export:
export:
to AS2
action community.append(1:1);
announce AS4
to AS3
announce AS4
29
RAToolSet (Version 4)



router Configuration tools (RtConfig)
paths analysis tools
(prpath and prtraceroute)
edit, compare,validate and register
RPSL objects (roe, aoe and prcheck)
Autonomous system Object Editor
30
Using RtConfig


Generating router configuration from
RPSL
Steps
– register policy in an IRR
– building a RtConfig source file
– create vendor specific router configuration
by the source file and policy in IRR
(support cisco,juniper, gated, bay/nortel)
31
Using RtConfig
AS2914
AS3701
198.32.162.6
198.32.162.2
198.32.162.1
128.223.0.0/16
AS3582
32
Sample RtConfig Source File
Router bgp
3582
network 128.223.0.0
!
!
Start with access-list 100
!
@RtConfig set cisco_access_list_no = 100
!
NERO
neighbor 192.32.162.2 remote-as 3701
@RtConfig set cisco_map_name = “AS3701-EXPORT”
@RtConfig export AS3582 198.32.162.1 AS 3701 198.32.162.2
@RtConfig set cisco_map_name = “AS3701-IMPORT”
@RtConfig import AS3582 198.32.162.1 AS3701 198.32.162.2
!
!
WNA/VERIO
neighbor 198.32.162.6 remote-as 2914
@RtConfig set cisco_map_name = “AS2914-EXPORT”
@RtConfig export AS3582 198.32.162.1 AS2914 198.32.162.6
@RtConfig set cisco_map_name = “AS2914-IMPORT”
@RtConfig import AS3582 198.32.162.1 AS2914 198.32.162.6
33
Router Configuration File
router
bgp 3582
network 128.223.0.0
!
! NERO
neighbor 193.32.162.2 remote-as 3701
no access-list 100
access-list 100 permit ip 128.223.0.0 0.0.0.0 255.255.0.0 0.0.0.0
access-list 100 deny deny ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255
!
no route-map AS3701-EXPORT
route-map AS3701-EXPORT permit 1
match ip address 100
!
Router bgp 3582
neighbor 198.32.162.2 route-map AS3701-EXPORT out
!
No route-map AS3701-IMPORT
route-map AS3701-IMPORT permit 1
set local-preference 1000
! Router bgp 3582
34
Router Configuration File
neighbor 198.32.162.2 route-map AS3701-IMPORT in
!
! WNA/VERIO
neighbor 198.32.162.6 remote-as 2914
!
No route-map AS 2914-EXPORT
route-map AS2914-EXPORT permit 1
match ip address 100
!
Router bgp 3582
neighbor 198.32.162.6 route-map AS2914-EXPORT out
no ip as-path access-list 100
ip as-path access-list 100 permit ^_2914((_[0_9]+))*_
(13|22|97|132|175|668|1914|2905|2914|3361|3381|3791|3937|
4178|4354|4571|4674|4683|5091|5303|5798|5855|5856|5881|6083
|6188|6971|7790|7951|8028))?$
!
No route-map AS2914-IMPORT
route-map AS2914_IMPORT permit 1
match as-path 100
set local-preference 998
\
\
\
35
Thanks !
36