RMU VLabNet 7.4.2-BGP_RR - Virtual Laboratory Networking Exercises – BGP Route Reflector Configuration

INFS6230 – RMU C&IS

 

Command Summary and Examples

 

In development

1.      Quagga makes the following commands available to support route reflection:

(See Quagga documentation, p. 61):

bgp cluster-id a.b.c.d

neighbor peer route-reflector-client

no neighbor peer route-reflector-client

At router configuration prompt:

bgp client-to-client        Configure client to client route reflection

bgp cluster-id              Configure Route-Reflector Cluster-id

 

Step sequence:

1)      configure both 119, 120 as iBGP (route reflector) neighbors; advertise network, declare cluster-id, declare RR-clients

2)      configure each of 116-118 as iBGP peer with both 119 and 120

 

Route reflection is implemented in BGP to improve scalability of autonomous systems. Where there are n ASBRs in an AS, it is necessary to establish n*(n-1)/2 iBGP peerings to support the full mesh topology required by BGP.

 

2.      Example Topology with Paired Reflectors:

Configuration, using AS 64504, Fall 2010, as an example:

 

 

 

reflector 1: (VM 119)

router bgp 64504

bgp router-id 10.10.10.119

  network 10.10.119.0/29

  redistribute connected

 

!

! Reflectors

!

  bgp cluster-id 10.10.10.0

  neighbor x.y.z.120 remote-as 64504

  neighbor x.y.z.120 description RR2

!

! Clients

!

  neighbor x.y.z.116 remote-as 64504

  neighbor x.y.z.116 description client1

  neighbor x.y.z.116 route-reflector-client

  neighbor x.y.z.117 remote-as 64504

  neighbor x.y.z.117 description client2

  neighbor x.y.z.117 route-reflector-client

  neighbor x.y.z.118 remote-as 64504

  neighbor x.y.z.118 description client3

  neighbor x.y.z.118 route-reflector-client

!

! External

!

  neighbor x.y.z.112 remote-as 64503

  neighbor x.y.z.112 prefix-list allowed-in in

  ip prefix-list allowed-in seq 5 deny 10.10.112.0/29

  ip prefix-list allowed-in seq 10 permit any

 

! logging

!

log syslog

log file /var/log/quagga/bgpd.log

log stdout

!

line vty

 

reflector 2: (VM 120)

router bgp 64504

bgp router-id 10.10.10.120

  network 10.10.120.0/29

  redistribute connected!

!

! Reflectors

!

  bgp cluster-id 10.10.10.0

  neighbor x.y.z.119 remote-as 64504

  neighbor x.y.z.119 description RR1

!

! Clients

!

  neighbor x.y.z.116 remote-as 64504

  neighbor x.y.z.116 description client1

  neighbor x.y.z.116 route-reflector-client

  neighbor x.y.z.117 remote-as 64504

  neighbor x.y.z.117 description client2

  neighbor x.y.z.117 route-reflector-client

  neighbor x.y.z.118 remote-as 64504

  neighbor x.y.z.118 description client3

  neighbor x.y.z.118 route-reflector-client

!

! External

!

  neighbor x.y.z.105 remote-as 64501

  neighbor x.y.z.105 prefix-list allowed-in in

  ip prefix-list allowed-in seq 5 deny 10.10.105.0/29

  ip prefix-list allowed-in seq 10 permit any

!

! logging

!

log syslog

log file /var/log/quagga/bgpd.log

log stdout

!

line vty

 

clients: (VMs 116, 117, 118)

router bgp 64504

  bgp router-id 10.10.10.116

  redistribute connected

!

! Reflectors

!

  neighbor x.y.z.119 remote-as 64504

  neighbor x.y.z.120 remote-as 64504

!

! External

!

  neighbor x.y.z.123 remote-as 64505

  neighbor x.y.z.123 prefix-list allowed-in in

ip prefix-list allowed-in seq 5 deny 10.10.123.0/29

ip prefix-list allowed-in seq 10 permit any

!

! logging

!

log syslog

log file /var/log/quagga/bgpd.log

log stdout

!

line vty

3.       Route Reflection and Cluster Configuration Rules:

a.       Each RR (Route Reflector) sends updates to all Reflector Clients

b.      RRs in redundant configuration (as here) must all have the same Cluster-id.

c.       If RR-client has more than 1 connection to an RR (as here), RRs must use same Cluster-id.

d.      RR-client would not have other non-RR-client iBGP sessions to other RR-clients.

e.       eBGP sessions to other ASs should be normally done at designated RR-clients (except in case of a Routeserver RR in a public exchange).

f.       Each RR must be fully meshed with all other RRs in same cluster (in this example case K2 mesh).

4.       Revised configuration file (recommended 1):

a.       Edit your /etc/quagga/bgpd.conf file to revise it in accordance with configuration examples above and resave.

b.      Stop both bgpd and zebra processes.

c.       Restart both, zebra first.

d.      If you are also running ripd and/or ospfd, include them in steps b and c as well; always restarting zebra first.

5.       Interactive configuration at the vtysh prompt (recommended 2):

a.       Enter configuration statements (comment lines not necessary)

b.      At end enter write memory (to save to configuration files).

c.       Note: the command redistribute connected belongs with the router information and may not be accepted in interactive configuration

d.      Note: do not enter comment lines (beginning with !) in interactive configuration (when logged in to the router or through vtysh).

6.       Interactive configuration at the config-router prompt (telnet localhost 2605), example from VM 119 in AS 64504:

<system prompt>

telnet localhost 2605

Password: zebra

bgpd> enable

Password: #####

bgpd# config t [Note Prompt changes from bgpd> to bgpd#]

bgpd(config)#

bgpd(config)# router bgp 64504                           çuse your AS-number (ASN)

bgpd(config-router)# enter statements at this prompt

bgpd(config-router)# quit

bgpd(config)# quit

bgpd# show ip bgp <options>              çyou can enter show ip bgp commands here

bgpd# quit

<back to system prompt>

7.       Recommended Cluster-Ids and Reflector Assignments for Deploying Route Reflection:

ASN

Cluster-Id

Reflector 1

Reflector 2

Clients

Investigators

64501

10.10.10.0

101

104

102, 103, 105

Wiles, Wijeysooriya

64503

10.10.10.0

113

115

111, 112, 114

Kosturko, Гусьрэфович

8.       By using the ? option at the router configuration prompt, you can see what options you have:

bgpd(config-router)# ?

  address-family     Enter Address Family command mode

  aggregate-address  Configure BGP aggregate entries

  bgp                BGP specific commands

  distance           Define an administrative distance

  end                End current mode and change to enable mode.

  exit               Exit current mode and down to previous mode

  help               Description of the interactive help system

  ipv6               IPv6 information

  list               Print command list

  neighbor           Specify neighbor router

  network            Specify a network to announce via BGP

  no                 Negate a command or set its defaults

  quit               Exit current mode and down to previous mode

  redistribute       Redistribute information from another routing protocol

  show               Show running system information

  timers             Adjust routing timers

  write              Write running configuration to memory, network, or

                     terminal

 

bgpd(config-router)# bgp ?

  always-compare-med      Allow comparing MED from different neighbors

  bestpath                Change the default bestpath selection

  client-to-client        Configure client to client route reflection

  cluster-id              Configure Route-Reflector Cluster-id

  confederation           AS confederation parameters

  dampening               Enable route-flap dampening

  default                 Configure BGP defaults

  deterministic-med       Pick the best-MED path among paths advertised from

                          the neighboring AS

  enforce-first-as        Enforce the first AS for EBGP routes

  fast-external-failover  Immediately reset session if a link to a directly

                          connected external peer goes down

  graceful-restart        Graceful restart capability parameters

  log-neighbor-changes    Log neighbor up/down and reset reason

  network                 BGP network command

  router-id               Override configured router identifier

  scan-time               Configure background scanner interval

 

bgpd(config-router)# neighbor ?

  A.B.C.D   Neighbor address

  X:X::X:X  IPv6 address

  WORD      Neighbor tag

 

 

9.       Experiment: compare router command results before and after implementing route reflection for your Autonomous System (all Border Routers).

10.    Exercises: Verify route reflection by packet capture using tcpdump and/or tshark.

11.    Topology recommendation (using AS 64504 as an example):

 

Paired Reflectors (Redundancy)

 

i6230RR2_2010.jpg

 

3.       Documentation1:

ip route | sort:

vm-test:/home/test# ip route | sort

10.10.10.96/27 dev eth1  proto kernel  scope link  src 10.10.10.100

10.10.100.0/29 dev eth1  proto kernel  scope link  src 10.10.100.1

10.10.101.0/29 via x.y.z.101 dev eth0  proto zebra

10.10.102.0/29 via x.y.z.102 dev eth0  proto zebra

10.10.103.0/29 via x.y.z.103 dev eth0  proto zebra

10.10.104.0/29 via x.y.z.104 dev eth0  proto zebra

10.10.105.0/29 via x.y.z.105 dev eth0  proto zebra

10.10.106.0/29 via x.y.z.106 dev eth0  proto zebra

10.10.107.0/29 via x.y.z.107 dev eth0  proto zebra

10.10.108.0/29 via x.y.z.108 dev eth0  proto zebra

10.10.109.0/29 via x.y.z.109 dev eth0  proto zebra

10.10.110.0/29 via x.y.z.110 dev eth0  proto zebra

10.10.111.0/29 via x.y.z.111 dev eth0  proto zebra

10.10.112.0/29 via x.y.z.112 dev eth0  proto zebra

10.10.113.0/29 via x.y.z.113 dev eth0  proto zebra

10.10.114.0/29 via x.y.z.114 dev eth0  proto zebra

10.10.115.0/29 via x.y.z.115 dev eth0  proto zebra

10.10.116.0/29 via 10.10.10.116 dev eth1  proto zebra  metric 20

10.10.117.0/29 via x.y.z.117 dev eth0  proto zebra

10.10.118.0/29 via x.y.z.118 dev eth0  proto zebra

10.10.119.0/29 via x.y.z.119 dev eth0  proto zebra

10.10.120.0/29 via x.y.z.120 dev eth0  proto zebra

10.10.121.0/29 via x.y.z.121 dev eth0  proto zebra

10.10.122.0/29 via 10.10.10.122 dev eth1  proto zebra  metric 20

10.10.123.0/29 via x.y.z.123 dev eth0  proto zebra

10.10.124.0/29 via x.y.z.124 dev eth0  proto zebra

10.10.125.0/29 via x.y.z.125 dev eth0  proto zebra

10.10.98.0/29 via 10.10.10.98 dev eth1  proto zebra  metric 20

x.y.z.96/27 dev eth0  proto kernel  scope link  src x.y.z.100

default via x.y.z.97 dev eth0

vm-test:/home/test#

 

netstat -rn

vm-test:/home/test# netstat -rn

Kernel IP routing table

Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface

10.10.101.0     x.y.z.101  255.255.255.248 UG        0 0          0 eth0

10.10.117.0     x.y.z.117  255.255.255.248 UG        0 0          0 eth0

10.10.116.0     10.10.10.116    255.255.255.248 UG        0 0          0 eth1

10.10.100.0     0.0.0.0         255.255.255.248 U         0 0          0 eth1

10.10.103.0     x.y.z.103  255.255.255.248 UG        0 0          0 eth0

10.10.119.0     x.y.z.119  255.255.255.248 UG        0 0          0 eth0

10.10.102.0     x.y.z.102  255.255.255.248 UG        0 0          0 eth0

10.10.118.0     x.y.z.118  255.255.255.248 UG        0 0          0 eth0

10.10.113.0     x.y.z.113  255.255.255.248 UG        0 0          0 eth0

10.10.112.0     x.y.z.112  255.255.255.248 UG        0 0          0 eth0

10.10.115.0     x.y.z.115  255.255.255.248 UG        0 0          0 eth0

10.10.114.0     x.y.z.114  255.255.255.248 UG        0 0          0 eth0

10.10.98.0      10.10.10.98     255.255.255.248 UG        0 0          0 eth1

10.10.109.0     x.y.z.109  255.255.255.248 UG        0 0          0 eth0

10.10.125.0     x.y.z.125  255.255.255.248 UG        0 0          0 eth0

10.10.124.0     x.y.z.124  255.255.255.248 UG        0 0          0 eth0

10.10.108.0     x.y.z.108  255.255.255.248 UG        0 0          0 eth0

10.10.111.0     x.y.z.111  255.255.255.248 UG        0 0          0 eth0

10.10.110.0     x.y.z.110  255.255.255.248 UG        0 0          0 eth0

10.10.105.0     x.y.z.105  255.255.255.248 UG        0 0          0 eth0

10.10.121.0     x.y.z.121  255.255.255.248 UG        0 0          0 eth0

10.10.104.0     x.y.z.104  255.255.255.248 UG        0 0          0 eth0

10.10.120.0     x.y.z.120  255.255.255.248 UG        0 0          0 eth0

10.10.107.0     x.y.z.107  255.255.255.248 UG        0 0          0 eth0

10.10.123.0     x.y.z.123  255.255.255.248 UG        0 0          0 eth0

10.10.106.0     x.y.z.106  255.255.255.248 UG        0 0          0 eth0

10.10.122.0     10.10.10.122    255.255.255.248 UG        0 0          0 eth1

10.10.10.96     0.0.0.0         255.255.255.224 U         0 0          0 eth1

x.y.z.96   0.0.0.0         255.255.255.224 U         0 0          0 eth0

0.0.0.0         x.y.z.97   0.0.0.0         UG        0 0          0 eth0

vm-test:/home/test#

 

(in router) show ip bgp (source ASBR 100 in AS 64506)

bgpd# show ip bgp

BGP table version is 0, local router ID is 10.10.10.100

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale, R Removed

Origin codes: i - IGP, e - EGP, ? - incomplete

 

   Network          Next Hop            Metric LocPrf Weight Path

*  10.10.10.96/27   x.y.z.103                         0 64501 ?

*                   x.y.z.115           1             0 64503 ?

*>i                 x.y.z.98            1    100      0 ?

*>i10.10.98.0/29    x.y.z.98            1    100      0 i

*> 10.10.100.0/29   0.0.0.0                  0         32768 i

*> 10.10.101.0/29   x.y.z.101                         0 64501 i

* i                 x.y.z.101                100      0 64501 i

*> 10.10.102.0/29   x.y.z.102                         0 64501 i

* i                 x.y.z.102                100      0 64501 i

*> 10.10.103.0/29   x.y.z.103                         0 64501 ?

*>i10.10.104.0/29   x.y.z.104                100      0 64501 i

*> 10.10.105.0/29   x.y.z.105                         0 64501 i

* i                 x.y.z.105                100      0 64501 i

*  10.10.106.0/29   x.y.z.106                         0 64501 64502 i

*>                  x.y.z.106                         0 64503 64502 i

* i                 x.y.z.106                100      0 64505 64502 i

*                   x.y.z.106                         0 64505 64502 i

*  10.10.107.0/29   x.y.z.107                         0 64501 64502 i

*>                  x.y.z.107                         0 64503 64502 i

* i                 x.y.z.107                100      0 64505 64502 i

*                   x.y.z.107                         0 64505 64502 i

*  10.10.108.0/29   x.y.z.108                         0 64501 64502 i

*                   x.y.z.108                         0 64503 64502 i

* i                 x.y.z.108                100      0 64505 64502 i

*>                  x.y.z.108                         0 64505 64502 i

*  10.10.109.0/29   x.y.z.109                         0 64501 64502 i

*>                  x.y.z.109                         0 64503 64502 i

* i                 x.y.z.109                100      0 64505 64502 i

*                   x.y.z.109                         0 64505 64502 i

*  10.10.110.0/29   x.y.z.110                         0 64501 64502 i

* i                 x.y.z.110                100      0 64501 64502 i

*>                  x.y.z.110                         0 64503 64502 i

*> 10.10.111.0/29   x.y.z.111                         0 64503 i

*> 10.10.112.0/29   x.y.z.112                         0 64503 i

*> 10.10.113.0/29   x.y.z.113                         0 64503 i

*> 10.10.114.0/29   x.y.z.114                         0 64503 i

*>i10.10.115.0/29   x.y.z.115                100      0 64505 64504 64503 i

*  10.10.117.0/29   x.y.z.117                         0 64501 64504 i

*>                  x.y.z.117                         0 64503 64504 i

* i                 x.y.z.117                100      0 64501 64504 i

*  10.10.118.0/29   x.y.z.118                         0 64501 64504 i

*                   x.y.z.118                         0 64505 64504 i

*>                  x.y.z.118                         0 64503 64504 i

* i                 x.y.z.118                100      0 64501 64504 i

*  10.10.119.0/29   x.y.z.119                         0 64501 64504 i

*                   x.y.z.119                         0 64505 64504 i

*>                  x.y.z.119                         0 64503 64504 i

* i                 x.y.z.119                100      0 64501 64504 i

*  10.10.120.0/29   x.y.z.120                         0 64505 64504 i

* i                 x.y.z.120                100      0 64505 64504 i

*>                  x.y.z.120                         0 64503 64504 i

*> 10.10.121.0/29   x.y.z.121                         0 64505 i

*>i10.10.122.0/29   x.y.z.122                100      0 64505 i

* i10.10.123.0/29   x.y.z.123                100      0 64505 i

*>                  x.y.z.123                         0 64505 i

*> 10.10.124.0/29   x.y.z.124                         0 64505 i

* i                 x.y.z.124                100      0 64505 i

* i10.10.125.0/29   x.y.z.125                100      0 64505 i

*>                  x.y.z.125                         0 64505 i

*  x.y.z.96/27 x.y.z.103                         0 64501 ?

*                   x.y.z.115           1             0 64503 ?

*>i                 x.y.z.98            1    100      0 ?

 

Total number of prefixes 28

bgpd#

 

Next Hop Routing Path (AS-path): 

NextHopRouting.tif

13.  Monitoring Route Reflection – Show run for VM101 (RR):

 

bgpd# show run

Current configuration:
!
hostname bgpd
password zebra
enable password horse
log file /var/log/quagga/bgpd.log
log stdout
log syslog
!
router bgp 64501
 bgp router-id 10.10.10.101
 bgp cluster-id 10.10.10.0
 network 10.10.101.0/29
 redistribute connected
 neighbor x.y.z.102 remote-as 64501
 neighbor x.y.z.102 description client1
 neighbor x.y.z.102 route-reflector-client
 neighbor x.y.z.103 remote-as 64501
 neighbor x.y.z.103 description client2
 neighbor x.y.z.103 route-reflector-client
 neighbor x.y.z.104 remote-as 64501
 neighbor x.y.z.104 description RR2
 neighbor x.y.z.105 remote-as 64501
 neighbor x.y.z.105 description client3
 neighbor x.y.z.105 route-reflector-client
 neighbor x.y.z.108 remote-as 64502
 neighbor x.y.z.108 prefix-list allowed-in in
!
ip prefix-list allowed-in seq 5 deny 10.10.108.0/29
ip prefix-list allowed-in seq 10 permit any
!
line vty
!
end
bgpd#

 

14.    Monitoring Route Reflection – showing Originator-id and Cluster-id (list): Obtained from RR-client.

 

bgpd# show ip bgp x.y.z.113

BGP routing table entry for x.y.z.96/27

Paths: (4 available, best #4, table Default-IP-Routing-Table)

  Advertised to non peer-group peers:

  x.y.z.113 x.y.z.115 x.y.z.119

  Local

    x.y.z.113 (metric 1) from x.y.z.113 (10.10.10.113)

      Origin incomplete, metric 1, localpref 100, valid, internal

      Last update: Wed Dec  8 02:24:35 2010

 

  64504

    x.y.z.119 from x.y.z.119 (10.10.10.119)

      Origin incomplete, metric 1, localpref 100, valid, external

      Last update: Wed Dec  8 02:24:35 2010

 

  Local

    x.y.z.111 (metric 1) from x.y.z.115 (10.10.10.111)

      Origin incomplete, metric 1, localpref 100, valid, internal

      Originator: 10.10.10.111, Cluster list: 10.10.10.0

      Last update: Wed Dec  8 02:24:34 2010

 

  Local

    0.0.0.0 from 0.0.0.0 (10.10.10.112)

      Origin incomplete, metric 1, localpref 100, weight 32768, valid, sourced, best

      Last update: Wed Dec  8 02:24:29 2010

 

bgpd#

 

15.    Monitoring Route Reflection – referring to RR-client: Obtained from Route Reflector (RR).

 

bgpd# show ip bgp 10.10.105.0/29

BGP routing table entry for 10.10.105.0/29

Paths: (3 available, best #3, table Default-IP-Routing-Table)

  Advertised to non peer-group peers:

  x.y.z.111 x.y.z.112 x.y.z.114 x.y.z.115

  64502 64501, (Received from a RR-client)

    x.y.z.101 (metric 1) from x.y.z.114 (10.10.10.114)

      Origin IGP, localpref 100, valid, internal

      Last update: Wed Dec  8 02:42:59 2010

 

  64506 64501

    x.y.z.105 (metric 1) from x.y.z.115 (10.10.10.115)

      Origin IGP, localpref 100, valid, internal

      Last update: Wed Dec  8 02:06:18 2010

 

  64502 64501

    x.y.z.101 from x.y.z.106 (10.10.10.106)

      Origin IGP, localpref 100, valid, external, best

      Last update: Sun Dec  5 22:34:11 2010

 

bgpd#

 

16.    ASNs with and without Route Reflection, Fall 2010:

 

i6230eBGPPeer_RR.jpg

 

 

17.    Documentation 2:

·        Pepelnjak I, “BGP Route Reflectors,” http://wiki.nil.com/BGP_route_reflectors

·        http://www.networkliquidators.com/article-cisco-ccnp-bsci-certification-bgp-route-reflector-tutorial.asp

·        http://www.computerfreetips.com/cisco-router/BGP-Route-Reflectors.html

·        http://evilrouters.net/2010/03/08/bgp-route-reflectors/

·        http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800c95bb.shtml

·        RFC: http://tools.ietf.org/html/rfc4271 , BGP

·        RFC: http://tools.ietf.org/html/rfc4456 (2006)

·        Juniper, “Application note: Differences Between BGP Route Reflectors and Confederations,” https://www.juniper.net/customers/csc/documentation/techdocs/downloads/pdf/350010.pdf

·        Cisco Best Path selection: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml 

·        Standard Cisco Routing Table: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094823.shtml

·        Chen and Rekhter, “Cooperative Route Filtering Capability for BGP-4”  http://tools.ietf.org/html/draft-ietf-idr-route-filter-09

·        http://www.networkers-online.com/blog/2009/02/bgp-route-reflector-basics/

·        Schmied G, Integrated Cisco and UNIX® Network Architectures (Ciscopress, 2005), Lab 10-1, “Route Reflection,” pp. 251-267.

 

Bit budget for ORIGINATOR_ID: 4 bytes (32 bits)

Bit budget for CLUSTER_ID: 4 bytes (32 bits)

 

m, n = student domain number {nÎN | ((n ≥ 101) Ù (n ≤ 125))}

x.y.z. = first three octets of assigned routable network addresses for INFS6230

Valerie J. H. Powell, RMU C&IS; Randall S. Johnson, RMU IT Services; thanks to Ingo Flaschberger, Crossip Communications GmbH (http://www.crossip.net/, Vienna, Austria), input and guidance on this topic.

© 2010 by Robert Morris University

Update: 2011-11-24