Bgp

Introduction to Border Gateway Protocol (BGP 4)

Version 1.2

Updated 8/22/00 Juniper Networks, Inc. Copyright © 2000 - Proprietary & Confidential 2

Summary

BGP Concept

BGP Operation

Route Control

Configuration

Trouble-shooting

Juniper vs. Cisco


Summary

BGP Concept

BGP Operation

Route Control

Configuration

Trouble-shooting

Juniper vs. Cisco


Concepts

The BGP protocol was developed by the IDR Working Group of IETF. A first version of BGP was published in June 1989 as RFC 1105 (BGP-1). A second version was published in June 1990 as RFC 1163 (BGP-2). A third version was published in October 1991 as RFC 1267 (BGP-3).

A fourth version was published in July 1994 as RFC 1654 (BGP-4). The Current version of BGP-4 is documented in RFC 1771 (March 1995).

BGP-4 supports the path vector concept to avoid the potential routing loop introduced by

complicated (I.e., full-meshed) Internet topology

IP prefix and length advertisements


JUNOS software supports BGP Version 4 and several extensions to the protocol RFC 1771, A Border Gateway Protocol 4 (BGP-4) RFC 1772, Application of the Border Gateway Protocol in the

Internet RFC 1965, Autonomous System Confederations for BGP RFC 1966, BGP Route Reflection: An Alternative to Full-Mesh IBGP RFC 1997, BGP Communities Attribute RFC 2270, Using a Dedicated AS for Sites Homed to a Single

Provider RFC 2283, Multiprotocol Extensions for BGP-4 RFC 2385, Protection of BGP Sessions via the TCP MD5 Signature

Option RFC 2439, BGP Route Flap Damping Capabilities Negotiation with BGP4, IETF draft draft-ietf-idr-cap-

neg-01 BGP Extended Communities Attribute, IETF draft-ramachandra-bgp-

ext-communities-04.txt

BGP Protocol Overview


Concepts the concept of classless interdomain routing to allow better use of

existing IP address space and to minimize the rapid growth of routing table size (CIDR, RFC 1519)

policy-based routing using a set of pre-defined path attributes BGP-4 supports route aggregation and AS aggregation (I.e., AS

Set and Confederation) fast convergence by requiring the router to inform its neighbors

when the previously announced routes become unreachable large routing table size authentication using BGP identifier and AS number. In addition, it

supports encrypted signature in every BGP message.


Concepts BGP routers only use those routes whose next-hop can be reached BGP routers advertise only those routes that they use BGP runs over a reliable transport protocol.

TCP port 179 takes care of segmenting, sequencing, retransmission and

acknowledgments supports a "graceful" close, i.e., that all outstanding data will be

delivered before the connection is close. - 4096 max frame size - hold time (90 sec def – smallest used between peers) - open->updates->keepalives (steady state)-> notification

(close) | | ----------------

BGP MIB consists of the BGP Peer Table, The BGP Path Attribute Table and a Global Table.


Concepts

Autonomous System (AS)

The classic definition of an Autonomous System is a set of routers under a single technical administration, using a single IGP and common metrics to route packets within the AS, and using an EGP to route packets to other ASs.

Currently, it has become common for a single AS to use several IGPs and sometimes several sets of metrics within an AS.

The use of the term Autonomous System here stresses the fact that, even when multiple IGPs and metrics are used, the administration of an AS appears to other ASs to have a single coherent interior routing plan and presents a consistent picture of what destinations are reachable through it.


ConceptsAutonomous System Type

• Stub AS– Single Exit Point– Local Traffic

• Multi-Homed AS– Multiple Exit Points– Local Traffic

•Transit AS– Local and Transit Traffic

Provider "A"

AS 50

Provider "B"

AS 60

Customer #1AS 100

Customer #2AS 110

Customer #nAS 120

EBGP

IBGP

Stub AsStub As

Multi-HomedMulti-Homed

Stub AsStub As

Transit ASTransit AS

Transit ASTransit AS

TCP Connections

BGP Peers


BGP AS

What is an AS? - 16 bit integer (1-65535) - 64512-65535 private.


Concepts

CIDR = Classless Inter Domain Routing

Address Assignment and Aggregation Strategy A mechanism to aggregate IP addresses into blocks of

multiple of the old style classes of addresses Reduces routing information through this aggregation Conserves Resources

router resources (CPU, memory) bandwidth (less routes -> less routing packets)


Concepts

SupernetOrganizations are allocated Blocks of IP addresses

These blocks are allocated in powers of 2

The Blocks of Address Space can be Aggregated into one routing announcement (Supernetting)

Block of 256 “Class C” Networks (or a class B sized block) IP addresses 192.24.0.0 thru 192.24.255.255 Can be described by one Supernetted Route

192.24.0.0 Mask 255.255.0.0


Concepts

Exterior Routes

Routes learned from other autonomous systems


Concepts

Between BGP Speakers in different AS

Should be directly connected Configuration

Router A

bgp {

group EXTERNAL {

neighbor 1.1.1.2;

type external;

peer-as 200 ;

}

{

Router B

bgp {

group EXTERNAL {

neighbor 1.1.1.1;

type external;

peer-as 100 ;

}

{

External Neighbor

AS 100

AS 200

1.1.1.0

.1

.2

A

B


Concepts

Neighbor in same AS May be several hop away Configuration

Router A

bgp {

group INTERNAL {

type internal;

neighbor 1.1.1.1;

}

}

Router B

bgp {

group INTERNAL {

neighbor 2.2.2.2;

type internal;

}

{

Internal Neighbor

AS 100

A

B


Concepts

Internal vs. External BGP

Local Preference MED

Cluster list

Next-hop address AS Path

IBGP Update

Preserved

Preserved

Prepend the Cluster ID

by RR

Preserved

Unchanged

EBGP Update

Removed

Removed the MED from previous AS

Unchanged

Changed to the local address

Prepend the local AS


BGP Attribute

Well-known mandatory – Always present in a BGP update. All BGP implementations recognize these attributes. An example is the BGP next hop attribute. (Origin, AsPath)

Well-known discretionary - Might be present in a BGP update. All BGP implementations recognize these attributes. An example is the local preference attribute.

Optional transitive - Must be passed to other BGP peers even if the local peer does not understand or process the attribute. An example is the community attribute.

Optional non-transitive - Must not be passed to other BGP peers. An example is the MED attribute


Concepts

AS path Attributes Standard attribute types

1, ORIGIN (well-known mandatory) 2, AS_PATH (well-known mandatory) 3, NEXT_HOP (well-known mandatory) 4, MULTI_EXIT_DISC (optional non-transitive) 5, LOCAL_PREF (well-known discretionary) 6, ATOMIC_AGGREGATE (well-known discretionary) 7, AGGREGATOR (optional transitive)

Additional attribute types have been created via supplemental specifications to extend the protocol

8, Community (optional transitive) 9, Originator Id (optional non-transitive) 10, Cluster list (optional non-transitive) 11, Destination Path Attribute (optional transitive)


Concepts

Path traversed one or more members of a set

{100 200} (as-set)

A list of AS’s that a route has traversed

300 100 (sequence)

AS-Path

100143.89.14.0/24

206.161.46.0/24200

206.161.47.0/24

300210.168.35.0/24

143.89.14.0/24 300 100210.168.35.0/24 300206.161.46.0/23 300 {100 200}


Concepts

set by EBGP speaker or policy

Next hop to reach a network Router A will advertise 100.100.100.1 next hop for network 150.10.0.0

Next-hop

100.100.100.0

AS 109150.10.0.0/16

B

A

.2

.1

AS 173


Concepts

Router B would advertise 100.100.100.3 as an “next-hop” to reach the network behind router C to AS 109 ( router A )

Next-hop Issue

.1

100.100.100.0/24

AS 109

AS 173

.2 .3

EBGP

Router A

Router B Router C


Concepts

Problem will occur if the network in-between is actually an NBMA network !

Next-hop Issue

.1

100.100.100.0/24

AS 109

AS 173

.2 .3

EBGP

Router A

Router B Router C


Concepts

Use “next-hop self” to solve

Next-hop Issue

.1

100.100.100.0/24

AS 109

AS 173

.2 .3

EBGP

Router A

Router B Router C

Router B:protocol bgp {

group BGP-to-router-A {

export chg-nexthop;

}

}

policy-options policy-statement chg-nexthop {

from protocol bgp;

then next-hop self;

}


Concepts

Preference send to all routers in local AS Path with highest preference value are most desirable

Local Preference

AS 173

AS 180

AS 666AS 200

Where to 200 ??


Concepts

Local Preference

bgp { group EXTERNAL { type external;

peer-as 666 local-preference 100; neighbor 1.1.1.1; }}

AS 173

AS 180

AS 666AS 200


Concepts

Multi-Exit Discriminator (MED)

32-bit, non-negative

Affects all routes from same AS path

Advertised to external neighbors

Lower MED value is more preferable


Concepts

Applies on a AS path basis


AS 666

AS 173

AS 200

AS 2000

AS 1800

AS 1988


Concepts

Multi-Exit Discriminator (MED)Router A:

bgp {

group EXTERNAL {

type external;

neighbor 1.1.1.1 {

export MED;

peer-as 666;

}

}

}

policy-statement MED {

from as-path via-200;

then {

metric 200;

accept;

}

}

as-path via-200 ".* 200";


Concepts


AS 666

AS 173

AS 200

AS 2000

AS 1800

AS 1988

A

set MED = 200


Concepts

Origin describes how a route was injected into BGP at the originating AS

IGPDefault export type on policy statement for BGP

EGPFrom protocol EGP, can be specified in the export policy

IncompleteUnknown source of information, can be specified in the export policy


Concepts

Atomic Aggregate

Used to inform BGP speaker about less specific route.

More specific route exists and is included in it

BGP speaker receiving this attribute shall not remove the attribute when propagating it


Concepts

Aggregator (6-bytes)

Last AS number that formed the aggregate route (2 bytes)

IP address of the BGP speaker that formed the aggregate route (4-bytes)


Concepts

Route Reflector and Confederation

Scaling would be an issue when there are too many BGP peer within the AS

BGP speaker would not pass the BGP routes learn from an IBGP peer to another IBGP peers

Number of connection required = n(n-1)/2


Concepts

Route Reflector – RFC 1966 Acting as a “mirror” to reflect the BGP routes learned

from the IBGP peers to the clients Update from non-client to all clients Update from client to all non-clients and the other clients

except the one originated the route Provide the normal BGP speaker function to all other

non-clients Pending cluster-list and originator ID


Concepts

Route Reflector

AS100

AS300

AS200

EBGP EBGP

IBGP

client client

RR

non-client

IBGP

IBGP

AS100

AS300

AS200

EBGP EBGP

IBGP

IBGP

IBGP

IBGP

IBGP

IBGP

IBGP


Concepts

Route Reflector Loop Prevention

Originator ID

If the attribute “originator ID” has not been created in the attribute of the route, the RR will create this attribute

The content of “originator ID” is the router ID of the IBGP peer that pass this route to the RR

The RR would not reflect the route back to the The RR would not reflect the route back to the originatororiginator


Concepts

Route Reflector Loop Prevention

Cluster list

When the RR reflect the route to other peers, it will prepend it’s cluster ID within the cluster list

If the RR receive a route with it’s cluster ID within the If the RR receive a route with it’s cluster ID within the cluster list, the route would be discardedcluster list, the route would be discarded


Concepts

Confederation – RFC 1965

Scale down an AS into several Sub-ASs Each BGP peers between sub-AS would act as EBGP peer

except some of the attributes remain unchanged Local-preference passed through such a connect MED, next-hop unchanged between member AS’s of the

confederation.


Concepts

Confederation

AS100

AS200

EBGP

IBGP

IBGP

IBGP

IBGP

IBGP

IBGP

IBGP

IBGP

IBGP

IBGP

AS100

AS200

EBGP

EBGP

IBGP

IBGP

IBGP

IBGP

AS65500

AS65501


Summary

BGP Concept

BGP Operation

Route Control

Configuration

Trouble-shooting

Juniper vs. Cisco


BGP Protocol Messages

Four types of messages Open Update Keepalive Notification


BGP HeaderBGP Header

0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + + | Marker | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

•Marker: synchronization and authentication


BGP Open messageBGP Open message

0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+ | Version | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | My Autonomous System | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Hold Time | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BGP Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Opt Parm Len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Optional Parameters | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


OPEN Message (Cont.)

Authentication Information (type 1)

Optional Parameters

0 1 2 3 4 5 6 7 8 +-+-+-+-+-+-+-+-+ | Auth. Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Authentication Data | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


NOTIFICATION Message

0 1 2 30 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Error code | Error subcode | Data |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

1 = HRD Error2 = OPEN Error3= UPDATE Error4 = Hold Time Expired5 = FSM Error6 = Cease(for fatal errors besides the ones already listed)


UPDATE Message

+-----------------------------------------------------+ | Unfeasible Routes Length (2 octets) | +-----------------------------------------------------+ | Withdrawn Routes (variable) | +-----------------------------------------------------+ | Total Path Attribute Length (2 octets) | +-----------------------------------------------------+ | Path Attributes (variable) | +-----------------------------------------------------+ | Network Layer Reachability Information (variable) | +-----------------------------------------------------+

+---------------------------+| Length (1 octet) |+---------------------------+| Prefix (variable) |+---------------------------+

0 10 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Attr. Flags |Attr. Type Code|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


BGP Operation

BGP TCP TCP BGP

Idle

Initializing

Open Sent

Open Confirm

Established

Syn SentListen

Syn Received

Idle

InitializingOpen Sent

Open Confirm

Established

EstablishedEstablished

Connect Connect

Open Open

KeepAlive KeepAlive

syn

Syn +Ack

Ack

BGP Peers

Update Update

BGP-4 Message Exchange


BGP Operation

Idle

Connect

Open Sent

Open Confirm

Established

Active

1

3

11

7

16

14

10

9

64

2

125

8

15

13

BGP-4 FSM


BGP OperationCurrent State

New State

Event

Idle Idle 1). Error Connect 2). Start

Connect Idle 3). Any other event

Connect 4). ConnectRetry Timer ExpiredOpen Sent 5). Transport Protocol Connect Succeeds

Active 6). Transport Protocol Connect Fails

Open Sent Idle 7). Stop, Open Error, Connection Collision, Hold Timer Expires, or any other event

Open Confirm 8). No Errors

Active 9). Disconnect Notification

Open sent--- Wait for open from peer Open sent--- Wait for open from peer


BGP Operation

Established 15). Keepalive

Open Confirm Idle 14). Hold Timer Expired, Notification, Disconnect, Stop, or any other event

Established Idle 16). Notification, UPDATE Message error Disconnect Notification, Hold Timer Expired, Stop, or any other event

Active Open SentConnectActive

Idle

10). Transport Connect Protocol Succeeds11). ConnectRetry Timer Expired12). Remote Peer Trying, IP Address Not Expected

13). Any Other Event

Current New Event State State

Open Confirm (waiting notification or keepalive – handshake)Open Confirm (waiting notification or keepalive – handshake)


Summary

BGP Concept

BGP Operation

Route Control

Configuration

Trouble-shooting

Juniper vs. Cisco


Route Control

Route Selection

Route with lowest preference value Route with highest local preference Route with the shortest AS path length Route with the lowest origin code ( IGP < EGP < incomplete ) Route with the lowest MED (cisco-nondeterministic / always-compare-med ) Routes are local generated Routes from EBGP peer Routes with the closest next-hop (determined by IGP metric) Routes from the peer with lowest router-id Routes from the neighbor with lowest IP address


Route Control

Policy Control

Import / Export PolicyCommunitiesAS pathRoute filtering


Route Control

Import / Export Policy

Per group / neighbor import / export policy

Used for advertise routes originated from the local AS

Used for change / add / delete BGP attributes

Global specific > Group specific > Neighbor specific


Route Control


Applying policies:bgp { import global-import-policy-here; export global-export-policy-here; group testing-policy { import group-import-policy-here; export group-export-policy-here; neighbor 1.1.1.1 { import neighbor-import-policy-here; export neighbor-export-policy-here; } }}


Route Control


Check the routes received from a peer before applying an import policy:

show route receive-protocol bgp 1.1.1.1

Check the routes sent to a peer after applying an export policy:

show route advertising-protocol bgp 1.1.1.1


Route Control

Community

Well-known communityno-advertise Do not advertise to neighbors

no-export Do not advertise outside your confederation/AS

no-export-subconfed Do not advertise outside your subconfederation

Define Communitycommunity community-name members [ 100:10 100:30 ];


Route Control

AS Path

AS Path Regular Expressions{m,n} at least m and most n repetitions of term.

{m} Exact m repetitions of term

{m,} m or more repetitions of term

* Zero or more repetitions of term

+ One or more repetitions of term

? Zero or one repetitions of term

| One of the two terms on either side of the pipe


Route Control

Route filtering

Filtering based on IP prefix / AS path / Community string / Neighbor / Origin …..

Import / Export policy


Route Control

Route filtering

Matching criteria+ as-path Name of AS path regular expression (BGP

only)

+ community BGP community

local-preference Local preference associated with a route

+ neighbor Neighboring router

Origin BGP origin attribute

> prefix-list List of prefix-lists of routes to match

> route-filter List of routes to match


Route Control

Route filtering

Matching AS Pathpolicy-statement filtering {

from as-path testing-as-path;

then accept;

}

as-path testing-as-path ".* 200";


Route Control

Route filtering

Matching Community stringpolicy-statement filtering {

from community testing-community;

then accept;

}

community testing-community members 100:200;


Route Control

Route filtering

Matching route entrypolicy-statement filtering {

from route-filter 100.100.0.0/16 orlonger;

then accept;

}


Route Control

Route filtering

Matching within a group of route entriesprefix-list route-list { 100.100.0.0/16; 100.110.0.0/16; 100.120.0.0/16;}policy-statement filtering { from prefix-list route-list;

then accept;}


Summary

BGP Concept

BGP Operation

Route Control

Configuration

Trouble-shooting

Juniper vs. Cisco


Configuration

BGP minimum configuration[routing-options]

autonomous-system <your own AS>;

[protocol bgp]

group BGP-setup {

type [external | internal];

peer-as <peer’s AS>;

neighbor <peer IP address>;

}


Configuration

Example[protocol bgp]

group BGP-setup {

type external;

peer-as 100;

neighbor 100.1.1.2;

}

[routing-options]

autonomous-system 200;


Configuration

Set the local-preference[protocol bgp]group BGP-setup { type external; local-preference 100; peer-as 100; neighbor 100.1.1.2;}

Set the MED[protocol bgp]group BGP-setup { type external; metric-out 200; local-preference 100; peer-as 100; neighbor 100.1.1.2;}


Configuration

Change the origin[protocol policy-options]

policy-statement change-origin {

from protocol aggregate;

then {

origin incomplete;

accept;

}

}

[protocol bgp]

group BGP-setup {

type external;

export change-origin;

peer-as 100;

neighbor 100.1.1.2;

}


Configuration

AS-prepend[policy-options]

policy-statement as-prepend {


then {

as-path-prepend “300 300 300";

accept;

}

}

[protocol bgp]

group BGP-setup {

type external;

export as-prepend;

peer-as 100;

neighbor 100.1.1.2;

}


Configuration

Attach community[protocol bgp]

group BGP-setup {

type external;

export att-community;

peer-as 100;

neighbor 100.1.1.2;

}

[policy-options]

policy-statement att-community {

then {

community set send-community;

}

}

community send-community members [ 100:10 200:10 ];


Configuration

Route Reflector[protocol bgp]

group RR-client {

type internal;

cluster 100.1.1.1;

neighbor 100.1.1.2;

neighbor 100.1.1.3;

}

group non-client {

type internal;

neighbor 10.1.1.2;

}

group EBGP {

type external;

peer-as 100;

neighbor 192.168.1.2;

}


Configuration

Confederation[routing-options]


confederation 200 members [ 65000 65001 ];

[protocol bgp]

group confe {

type external;

peer-as 65001;

neighbor 100.1.1.2;

}


Configuration

Advertise summary network[routing-options]

aggregate {

route 202.168.0.0/17 discard;

}

[policy-options]

policy-statement adv-summary {


then accept;

}

[protocol bgp]

group BGP-setup {

type external;

export adv-summary;

peer-as 100;

neighbor 100.1.1.2;

}


Configuration

Advertise the routing entries in other protocol [policy-options]

policy-statement adv-ospf {

from protocol ospf;

then accept;

}

[protocol bgp]

group BGP-setup {

type external;

export adv-ospf;

peer-as 100;

neighbor 100.1.1.2;

}


Summary

BGP concepts

BGP Operation

Route Control

Configuration

Trouble-shooting

Juniper vs. Cisco


Trouble-shooting

Checking the BGP neighbor status

root@router> show bgp summary

Groups: 1 Peers: 1 Down Peers: 0

Table Tot Paths Act Paths Suppressed History Damp State Pending

inet.0 0 0 0 0 0 0

inet.2 0 0 0 0 0 0

Peer AS InPkt OutPkt OutQ Flaps Last Up/Dwn State|#Active/Received/Damped...

100.1.1.2 65001 275 279 0 0 02:17:30 0/0/0 0/0/0


Trouble-shooting

Neighbor can’t establish



inet.0 0 0 0 0 0 0

inet.2 0 0 0 0 0 0


100.1.1.2 65001 0 4 0 0 00:00:57 Active

Enable traceoption[protocol bgp]

traceoptions {

file bgp-trace;

flag packets detail;

flag open detail;

}


Trouble-shooting

Monitoringroot@router> monitor start bgp-trace

*** bgp-trace ***

Nov 10 14:53:50

Nov 10 14:53:50 BGP RECV 100.1.1.2+1113 -> 100.1.1.1+179

Nov 10 14:53:50 BGP RECV message type 1 (Open) length 45

Nov 10 14:53:50 BGP RECV version 4 as 65001 holdtime 90 id 192.168.1.2 parmlen 16

Nov 10 14:53:50 MP capability AFI=1, SAFI=1

Nov 10 14:53:50 Refresh capability, code=128


Nov 10 14:53:50 bgp_pp_recv: dropping 100.1.1.2 (External AS 65001), connection collision prefers 100.1.1.2+1113 (proto)

Nov 10 14:53:50 bgp_send: sending 45 bytes to 100.1.1.2 (External AS 65001)

Nov 10 14:53:50

Nov 10 14:53:50 BGP SEND 100.1.1.1+179 -> 100.1.1.2+1113

Nov 10 14:53:50 BGP SEND message type 1 (Open) length 45


Trouble-shooting

MonitoringNov 10 14:53:50 BGP SEND version 4 as 65000 holdtime 90 id 192.168.1.1 parmlen 16

Nov 10 14:53:50 MP capability AFI=1, SAFI=1



Nov 10 14:53:50 bgp_send: sending 19 bytes to 100.1.1.2 (External AS 65001)

Nov 10 14:53:50

Nov 10 14:53:50 BGP SEND 100.1.1.1+179 -> 100.1.1.2+1113

Nov 10 14:53:50 BGP SEND message type 4 (KeepAlive) length 19

Nov 10 14:53:50

Nov 10 14:53:50 BGP RECV 100.1.1.2+1113 -> 100.1.1.1+179

Nov 10 14:53:50 BGP RECV message type 3 (Notification) length 21

Nov 10 14:53:50 BGP RECV Notification code 2 (Open Message Error) subcode 2 (bad peer AS number)

root@router> monitor stop bgp-trace


Trouble-shooting

ConfigurationNear end[routing-options]


confederation 200 members [ 65000 65001 65002 ];

[protocol bgp]

group bgp-demo {

type external;

peer-as 65001;

neighbor 100.1.1.2;

}

Far End[routing-options]


confederation 200 members [ 65000 65001 65002 ];

[protocol bgp]

admin@Jessie# show protocols bgp

group testing {

type external;

peer-as 65002;

neighbor 100.1.1.1;

}


Trouble-shooting Logged result:

root@router> file show /var/log/? Possible completions: <[Enter]> Execute this command <filename> Filename to display/var/log/bgp-trace Size: 2459, Last changed: Nov 7 18:41:08

Stop logging:root@router# delete protocols bgp traceoptions root@router# commit


Trouble-shooting

Other problem Local-address definition (cisco’s update-source)

[protocol bgp]

group <group> {

local-address <local IP address>;

}

Peer AS mis-configured

Peer address unreachable

Mulithop issue for EBGP[protocol bgp]

group <group> {

multihop;

}


Trouble-shooting

Problem Report“show bgp summary”“show bgp neighbor”“show bgp group”“show version”“show configuration”


Summary

BGP concepts

BGP Operation

Route Control

Configuration

Trouble-shooting

Juniper vs. Cisco


Presentation and command difference between Juniper and Cisco

Juniper:fxp1 { unit 0 { family inet { address 172.27.4.172/24; }

}}lo0 { unit 0 { family inet { address 192.168.1.3/32; }

}}routing-options {

autonomous-system 100;}group Cisco { type external; multihop; local-address 192.168.1.3; peer-as 200; neighbor 192.168.1.254;}

Cisco:interface Loopback0 ip address 192.168.1.254 255.255.255.255!interface Ethernet0 ip address 172.27.4.173 255.255.255.0!router bgp 200 neighbor 192.168.1.3 remote-as 100 neighbor 192.168.1.3 ebgp-multihop 255 neighbor 192.168.1.3 update-source Loopback0!

Juniper Cisco



root@Juniper> show bgp summary



inet.0 0 0 0 0 0 0

inet.2 0 0 0 0 0 0


192.168.1.254 200 12 14 0 0 00:05:46 0/0/0 0/0/0

Cisco#show ip bgp summary BGP table version is 1, main routing table version 1

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd192.168.1.3 4 100 14 14 1 0 0 00:05:39 0



root@Juniper> show bgp neighbor

Peer: 192.168.1.254+179 AS 200 Local: 192.168.1.3+3844 AS 100

Type: External State: Established Flags: <>

Last State: OpenConfirm Last Event: RecvKeepAlive

Last Error: None

Options: <Multihop Preference LocalAddress HoldTime PeerAS Refresh>

Local Address: 192.168.1.3 Holdtime: 90 Preference: 170

Number of flaps: 0

Peer ID: 192.168.1.254 Local ID: 192.168.1.3 Active Holdtime: 90

Keepalive Interval: 30

NLRI advertised by peer:

NLRI for this session: inet-unicast

Peer does not support Refresh capability



Table inet.0 Bit: 10000

Active Prefixes: 0

Received Prefixes: 0

Suppressed due to damping: 0

Table inet.2 Bit: 20000

Active Prefixes: 0

Received Prefixes: 0

Suppressed due to damping: 0

Last traffic (seconds): Received 3 Sent 3 Checked 3

Input messages: Total 16 Updates 0 Refreshes 0 Octets 304

Output messages: Total 18 Updates 0 Refreshes 0 Octets 368

Output Queue[0]: 0

Output Queue[1]: 0

Route Queue Timer: unset Route Queue: empty



Cisco#show ip bgp neighbors

BGP neighbor is 192.168.1.3, remote AS 100, external link

Index 1, Offset 0, Mask 0x2

BGP version 4, remote router ID 192.168.1.3

BGP state = Established, table version = 1, up for 00:08:45

Last read 00:00:15, hold time is 90, keepalive interval is 30 seconds

Minimum time between advertisement runs is 30 seconds

Received 20 messages, 0 notifications, 0 in queue

Sent 20 messages, 0 notifications, 0 in queue

Connections established 1; dropped 0

Last reset never

No. of prefix received 0

External BGP neighbor may be up to 255 hops away.

Connection state is ESTAB, I/O status: 1, unread input bytes: 0

Local host: 192.168.1.254, Local port: 179

Foreign host: 192.168.1.3, Foreign port: 3844

Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)



Event Timers (current time is 0x2590F0):Timer Starts Wakeups NextRetrans 21 0 0x0TimeWait 0 0 0x0AckHold 20 17 0x0SendWnd 0 0 0x0KeepAlive 0 0 0x0GiveUp 0 0 0x0PmtuAger 0 0 0x0DeadWait 0 0 0x0

iss: 401687383 snduna: 401687774 sndnxt: 401687774 sndwnd: 16384irs: 486200570 rcvnxt: 486200977 rcvwnd: 15978 delrcvwnd: 406

SRTT: 342 ms, RTTO: 1337 ms, RTV: 326 ms, KRTT: 0 msminRTT: 4 ms, maxRTT: 300 ms, ACK hold: 200 msFlags: passive open, nagle, gen tcbs

Datagrams (max data segment is 556 bytes):Rcvd: 25 (out of order: 0), with data: 20, total data bytes: 406Sent: 38 (retransmit: 0), with data: 20, total data bytes: 390



Juniper

no synchronization ( Default behavior )

set policy-options damping cisco

set routing-options confederation members

set protocols bgp group Cisco cluster

show bgp neighbor

show bgp summary

show route aspath-regex "200"

Cisco

no synchronization

bgp damping

bgp confederation

bgp cluster-id

show ip bgp neighbor

show ip bgp summary

show ip bgp regexp ^200$

http://www.juniper.net

Thank you!

Date post:	13-Jan-2015
Category:	Education
Upload:	febrian-setiadi
View:	4,563 times
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Bgp

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