NAME

bgpq3 - bgp filtering automation for Cisco and Juniper routers

SYNOPSIS

bgpq3 [-h host] [-S sources] [-EP] [-f asn | -G asn] [-346AbDdJjX] [-r len] [-R len] [-m max] [-W len] OBJECTS [...]

DESCRIPTION

The bgpq3 utility used to generate Cisco and Juniper prefix-lists, extended access-lists, policy-statement terms and as-path lists based on RADB data.

The options are as follows:

• -3

> assume that your device is asn32-capable.

• -4

> generate IPv4 prefix/access-lists (default).

• -6

> generate IPv6 prefix/access-lists (IPv4 by default).

• -A

> try to aggregate generated filters as much as possible (not all
output formats supported).

• -b

> generate output in BIRD format (default: Cisco).

• -d

> enable some debugging output.

• -D

> use asdot notation for Cisco as-path access-lists.

• -E

> generate extended access-list (Cisco) or policy-statement term using 
route-filters (Juniper).

• -f number

> generate input as-path access-list.

• -G number

> generate output as-path access-list.

• -h host

> host running IRRD database (default: whois.radb.net).

• -J

> generate config for Juniper (default: Cisco).

• -j

> generate output in JSON format (default: Cisco).

• -m len

> maximum length of accepted prefixes (default: 32 for IPv4, 128 for IPv6).

• -M match

> extra match conditions for Juniper route-filters.

• -l name

> name of generated entry.

• -P

> generate prefix-list (default behaviour, flag added for backward 
compatibility only).

• -r len

> allow more-specific routes with masklen starting with specified 
    length.

• -R len

> allow more-specific routes up to specified masklen too.
(Please, note: objects with prefix-length greater than specified length
will be always allowed.)

• -S sources

> use specified sources only (default: RADB,RIPE,APNIC).

• -T

> disable pipelining.

• -W len

> generate as-path strings of a given length maximum (0 for infinity).

• -X

> generate config for Cisco IOS XR devices (plain IOS by default).

OBJECTS means networks (in prefix format), autonomous systems, as-sets and route-sets.

EXAMPLES

Generating named Juniper prefix-filter for AS20597:

 user@host:~>bgpq3 -Jl eltel AS20597
 policy-options {
 replace:
  prefix-list eltel {
     81.9.0.0/20;
     81.9.32.0/20;
     81.9.96.0/20;
     81.222.128.0/20;
     81.222.192.0/18;
     85.249.8.0/21;
     85.249.224.0/19;
     89.112.0.0/19;
     89.112.4.0/22;
     89.112.32.0/19;
     89.112.64.0/19;
     217.170.64.0/20;
     217.170.80.0/20;
  }
 }

For Cisco we can use aggregation (-A) flag to make this prefix-filter more compact:

 user@host:~>bgpq3 -Al eltel AS20597
 no ip prefix-list eltel
 ip prefix-list eltel permit 81.9.0.0/20
 ip prefix-list eltel permit 81.9.32.0/20
 ip prefix-list eltel permit 81.9.96.0/20
 ip prefix-list eltel permit 81.222.128.0/20
 ip prefix-list eltel permit 81.222.192.0/18
 ip prefix-list eltel permit 85.249.8.0/21
 ip prefix-list eltel permit 85.249.224.0/19
 ip prefix-list eltel permit 89.112.0.0/18 ge 19 le 19
 ip prefix-list eltel permit 89.112.4.0/22
 ip prefix-list eltel permit 89.112.64.0/19
 ip prefix-list eltel permit 217.170.64.0/19 ge 20 le 20

and, as you see, prefixes 89.112.0.0/19 and 89.112.32.0/19 now aggregated into single entry

ip prefix-list eltel permit 89.112.0.0/18 ge 19 le 19.

Well, for Juniper we can generate even more interesting policy-statement, using -M <extra match conditions>, -r <len>, -R <len> and hierarchical names:

 user@host:~>bgpq3 -AJEl eltel/specifics -r 29 -R 32 -M "community blackhole" AS20597
policy-options {
 policy-statement eltel {
  term specifics {
replace:
   from {
    community blackhole;
    route-filter 81.9.0.0/20 prefix-length-range /29-/32;
    route-filter 81.9.32.0/20 prefix-length-range /29-/32;
    route-filter 81.9.96.0/20 prefix-length-range /29-/32;
    route-filter 81.222.128.0/20 prefix-length-range /29-/32;
    route-filter 81.222.192.0/18 prefix-length-range /29-/32;
    route-filter 85.249.8.0/21 prefix-length-range /29-/32;
    route-filter 85.249.224.0/19 prefix-length-range /29-/32;
    route-filter 89.112.0.0/17 prefix-length-range /29-/32;
    route-filter 217.170.64.0/19 prefix-length-range /29-/32;
   }
  }
 }
}

generated policy-option term now allows more-specific routes in range /29 - /32 for eltel networks if they marked with community 'blackhole' (defined elsewhere in configuration).

Of course, bgpq3 supports IPv6 (-6):

 user@host:~>bgpq3 -6l as-retn-6 AS-RETN6
 no ipv6 prefix-list as-retn-6
 ipv6 prefix-list as-retn-6 permit 2001:7fb:fe00::/48
 ipv6 prefix-list as-retn-6 permit 2001:7fb:fe01::/48
 [....]

and ASN32

 user@host:~>bgpq3 -J3f 112 AS-SPACENET
 policy-options {
 replace:
  as-path-group NN {
   as-path a0 "^112(112)*$";
   as-path a1 "^112(.)*(1898|5539|8495|8763|8878|12136|12931|15909)$";
   as-path a2 "^112(.)*(21358|23456|23600|24151|25152|31529|34127|34906)$";
   as-path a3 "^112(.)*(35052|41720|43628|44450|196611)$";
  }
 }

see AS196611 in the end of the list ? That's AS3.3 in 'asplain' notation.

If your router does not support ASN32 (yet) you should not use switch -3, and the result will be next:

 user@host:~>bgpq3 -f 112 AS-SPACENET
 no ip as-path access-list NN
 ip as-path access-list NN permit ^112( 112)*$
 ip as-path access-list NN permit ^112( [0-9]+)* (1898|5539|8495|8763)$
 ip as-path access-list NN permit ^112( [0-9]+)* (8878|12136|12931|15909)$
 ip as-path access-list NN permit ^112( [0-9]+)* (21358|23456|23600|24151)$
 ip as-path access-list NN permit ^112( [0-9]+)* (25152|31529|34127|34906)$
 ip as-path access-list NN permit ^112( [0-9]+)* (35052|41720|43628|44450)$

AS196611 is no more in the list, however, AS23456 (transition AS) would have been added to list if it were not present.

DIAGNOSTICS

When everything is OK, bgpq3 generates result to standard output and exits with status == 0. In case of errors they are printed to stderr and program exits with non-zero status.

NOTES ON ULTRA-LARGE PREFIX-LISTS

When using bgpq3 to expand extra-large AS-SETs, bgpq3 may stuck due to lacking tcp buffer size. To avoid this, tune your OS. FreeBSD can be tuned in the following way:

sysctl -w net.inet.tcp.sendbuf_max=16777216

Linux can be tuned in the following way:

sysctl -w net.ipv4.tcp_window_scaling=1
sysctl -w net.core.rmem_max=16777216
sysctl -w net.core.wmem_max=16777216
sysctl -w net.ipv4.tcp_rmem="4096 87380 16777216"
sysctl -w net.ipv4.tcp_wmem="4096 65536 16777216"

Please note that generated prefix-lists may not fit your router's limitations. For example, JunOS supports only 85,325 prefixes in each prefix-list 4.

SEE ALSO

1. Routing Arbiter
2. draft-michaelson-4byte-as-representation-05.txt for information on 'asdot' and 'asplain' notations.
3. Cisco documentation for information on Cisco implementation of ASN32.
4. JunOS prefix-lists limitation

AUTHOR

Alexandre Snarskii snar@snar.spb.ru

Program Homepage

http://snar.spb.ru/prog/bgpq3/