BGP · PART 1
packetlife.net
Attributes Name
About BGP
Description
Type Path Vector
Well-known Mandatory · Must be supported and propagated 1 Origin
Origin type (IGP, EGP, or unknown)
2 AS Path
List of autonomous systems which the advertisement has traversed
3 Next Hop
External peer in neighboring AS
Well-known Discretionary · Must be supported; propagation optional Metric for internal neighbors to reach external destinations (default 100)
5 Local Preference 6 Atomic Aggregate
Includes ASes which have been dropped due to route aggregation
Optional Transitive · Marked as partial if unsupported by neighbor 7 Aggregator
ID and AS of summarizing router
8 Commun munity ity
Route tag
Optional Nontransitive · Deleted if unsupported by neighbor 4
Multiple Exit Metric for external neighbors to reach t he Discriminator (MED) local AS (default 0)
9 Orig Origin inat ator or ID
The originator of a reflected route
10 Clus luster ter List List
List of cluster IDs
13 Cluster ID ID
Originating cluster
-- Weight
iBGP AD 200 Standard RFC 4271 Protocols IP Transport TCP/179 Authentication MD5 Terminology Autonomous System (AS) A logical domain under the control of a single entity
External BGP (eBGP) BGP adjacencies which span autonomous system boundaries
Internal BGP (iBGP) BGP adjacencies formed within a single AS
Synchronization Requirement A route must be known by an IGP before it may be advertised to BGP peers
Packet Types
Cisco proprietary, not communicated to peers (default 0) Path Selection
Attribute
eBGP AD 20
Open
Update
Keepalive
Notification
Neighbor States
Description
Preference
1 Weight
Administrative preference
Highest
Active · Attempting to connect
2 Local Preference
Communicated between peers within an AS
Highest
Connect · TCP session established
3 Self-originated
Prefer paths originated locally
True
4 AS Path
Minimize AS hops
Shortest
5 Origin
Prefer IGP-learned routes over EGP, and EGP over unknown
IGP
6 MED
Used externally to enter an AS
Lowest
show ip bgp [summary]
7 External
Prefer eBGP routes over iBGP
eBGP
show ip bgp neighbors
8 IGP Cost
Consider IGP metric
Lowest
show ip route [bgp]
9 eBGP Peering
Favor more stable routes
Oldest
clear ip bgp * [soft]
Tie breaker
Lowest
debug ip bgp […]
10 Router ID
Idle · Neighbor is not responding
Open Sent · Open message sent Open Confirm · Response received Established · Adjacency established Troubleshooting
Influencing Path Selection Weight neighbor 172.16.0.1 weight 200 MED default-metric 400 Ignore bgp bestpath as-path ignore AS Path by Jeremy Stretch
Local Preference bgp default local-preference 100 Route Map neighbor 172.16.0.1 route-map Foo Ignore Cost bgp bestpath cost-community ignore Communities v2.1-r1
BGP · PART 2
packetlife.net Configuration Example
AS 65100 F2/0 A S1/0
S1/1
172.16.0.0/30 172.16.0.4/30
AS 65200 S1/0
S1/0 F0/0
F0/0
10.0.0.0/30
B F2/0
C F2/0
OSPF
interface Serial1/0 description Backbone to B ip address 172.16.0.1 255.255.255.252 ! interface Serial1/1 description Backbone to C ip address 172.16.0.5 255.255.255.252 ! interface FastEthernet2/0 description LAN ip address 192.168.1.1 255.255.255.0 ! router bgp 65100 no synchronization network 172.16.0.0 mask 255.255.255.252 network 172.16.0.4 mask 255.255.255.252 network 192.168.1.0 neighbor South peer-group neighbor South remote-as 65200 neighbor 172.16.0.2 peer-group South neighbor 172.16.0.6 peer-group South no auto-summary
Router A
Router B interface FastEthernet0/0 description Backbone to C ip address 10.0.0.1 255.255.255.252 ! interface Serial1/0 description Backbone to A ip address 172.16.0.2 255.255.255.252 ! interface FastEthernet2/0 description LAN ip address 192.168.2.1 255.255.255.0 ! router ospf 100 network 10.0.0.1 0.0.0.0 area 0 network 192.168.2.1 0.0.0.0 area 1 ! router bgp 65200 no synchronization redistribute ospf 100 route-map LAN_Subnets neighbor 10.0.0.2 remote-as 65200 neighbor 172.16.0.1 remote-as 65100 no auto-summary ! access-list 10 permit 192.168.0.0 0.0.255.255 ! route-map LAN_Subnets permit 10 match ip address 10 set metric 100
Router C interface FastEthernet0/0 description Backbone to B ip address 10.0.0.2 255.255.255.252 ! interface Serial1/0 description Backbone to A ip address 172.16.0.6 255.255.255.252 ! interface FastEthernet2/0 description LAN ip address 192.168.3.1 255.255.255.0 ! router ospf 100 network 10.0.0.2 0.0.0.0 area 0 network 192.168.3.1 0.0.0.0 area 2 ! router bgp 65200 no synchronization redistribute ospf 100 route-map LAN_Subnets neighbor 10.0.0.1 remote-as 65200 neighbor 172.16.0.5 remote-as 65100 no auto-summary ! access-list 10 permit 192.168.0.0 0.0.255.255 ! route-map LAN_Subnets permit 10 match ip address 10 set metric 100
Router A Routing Table
Router B Routing Table
C C C B B
172.16.0.0/30 is subnetted, 2 subnets 172.16.0.4 is directly connected, S1/1 172.16.0.0 is directly connected, S1/0 192.168.1.0/24 is directly connected, F2/0 192.168.2.0/24 [20/100] via 172.16.0.2 192.168.3.0/24 [20/100] via 172.16.0.2
by Jeremy Stretch
B C C B C O
172.16.0.0/30 is subnetted, 2 subnets 172.16.0.4 [20/0] via 172.16.0.1 172.16.0.0 is directly connected, S1/0 10.0.0.0/30 is subnetted, 1 subnets 10.0.0.0 is directly connected, F0/0 192.168.1.0/24 [20/0] via 172.16.0.1 192.168.2.0/24 is directly connected, F2/0 IA 192.168.3.0/24 [110/2] via 10.0.0.2, F0/0
v2.1-r1
BGP · PART 2
packetlife.net Configuration Example
AS 65100 F2/0 A S1/0
S1/1
172.16.0.0/30 172.16.0.4/30
AS 65200 S1/0
S1/0 F0/0
F0/0
10.0.0.0/30
B F2/0
C F2/0
OSPF
interface Serial1/0 description Backbone to B ip address 172.16.0.1 255.255.255.252 ! interface Serial1/1 description Backbone to C ip address 172.16.0.5 255.255.255.252 ! interface FastEthernet2/0 description LAN ip address 192.168.1.1 255.255.255.0 ! router bgp 65100 no synchronization network 172.16.0.0 mask 255.255.255.252 network 172.16.0.4 mask 255.255.255.252 network 192.168.1.0 neighbor South peer-group neighbor South remote-as 65200 neighbor 172.16.0.2 peer-group South neighbor 172.16.0.6 peer-group South no auto-summary
Router A
Router B interface FastEthernet0/0 description Backbone to C ip address 10.0.0.1 255.255.255.252 ! interface Serial1/0 description Backbone to A ip address 172.16.0.2 255.255.255.252 ! interface FastEthernet2/0 description LAN ip address 192.168.2.1 255.255.255.0 ! router ospf 100 network 10.0.0.1 0.0.0.0 area 0 network 192.168.2.1 0.0.0.0 area 1 ! router bgp 65200 no synchronization redistribute ospf 100 route-map LAN_Subnets neighbor 10.0.0.2 remote-as 65200 neighbor 172.16.0.1 remote-as 65100 no auto-summary ! access-list 10 permit 192.168.0.0 0.0.255.255 ! route-map LAN_Subnets permit 10 match ip address 10 set metric 100
Router C interface FastEthernet0/0 description Backbone to B ip address 10.0.0.2 255.255.255.252 ! interface Serial1/0 description Backbone to A ip address 172.16.0.6 255.255.255.252 ! interface FastEthernet2/0 description LAN ip address 192.168.3.1 255.255.255.0 ! router ospf 100 network 10.0.0.2 0.0.0.0 area 0 network 192.168.3.1 0.0.0.0 area 2 ! router bgp 65200 no synchronization redistribute ospf 100 route-map LAN_Subnets neighbor 10.0.0.1 remote-as 65200 neighbor 172.16.0.5 remote-as 65100 no auto-summary ! access-list 10 permit 192.168.0.0 0.0.255.255 ! route-map LAN_Subnets permit 10 match ip address 10 set metric 100
Router A Routing Table
Router B Routing Table
C C C B B
172.16.0.0/30 is subnetted, 2 subnets 172.16.0.4 is directly connected, S1/1 172.16.0.0 is directly connected, S1/0 192.168.1.0/24 is directly connected, F2/0 192.168.2.0/24 [20/100] via 172.16.0.2 192.168.3.0/24 [20/100] via 172.16.0.2
by Jeremy Stretch
B C C B C O
172.16.0.0/30 is subnetted, 2 subnets 172.16.0.4 [20/0] via 172.16.0.1 172.16.0.0 is directly connected, S1/0 10.0.0.0/30 is subnetted, 1 subnets 10.0.0.0 is directly connected, F0/0 192.168.1.0/24 [20/0] via 172.16.0.1 192.168.2.0/24 is directly connected, F2/0 IA 192.168.3.0/24 [110/2] via 10.0.0.2, F0/0
v2.1-r1
CISCO IOS VERSIONS
packetlife.net
IOS Nomenclature
Release Lifecycle
12.4(7a)
Mainline Maintenance Release Individual Release Numbered Version
EOS Notice EOS EOE
12.4(9)T1
T Train
EOL 0
Maintenance Release Individual Release New Feature Identifier Numbered Version
12
36
48
60
72
84
96
Months
First Customer Shipment (FCS) The release is made available to Cisco customers on CCO
12.2(25)SEB4
S Train Release Individual Release Numbered Version
3.2.1
IOS XR Major Release Minor Release Maintenance Release
EOS Notice Notification of upcoming EOS End of Sale (EOS) The release is no longer orderable or included in manufactured shipments End of Engineering (EOE) The last day for software fixes; only TAC assistance is offered from this point End of Life (EOL) The last day for TAC support; release becomes obsolete; upgrade is only option for continued support IOS Filename
c3725-entbase-mz.124-6.T.bin
IOS Package Trees Advanced Enterprise Services
Advanced IP Services
Advanced Security
24
Enterprise Services
SP Services
Enterprise Base
Hardware Feature Set Memory Location Compression Format Maintenance Release Individual Release T Designator
Deployment Classifications IP Voice
Early Deployment (ED) Offers new feature, platform, or interface support
IP Base
General Deployment (GD) A major release considered qualified for deployment on critical devices
Advanced Enterprise Services
Adva Ad van nce ced d IP IP Ser Servi vice ces s
Ente terp rpri rise se Ser ervi vice ces s
Limited Deployment (LD) A major release prior to reaching its GD milestone Deferred (DF) Known defective images; should not be i nstalled IOS Version Verification
IP Services
show version dir
: : v2.0 ! Add networks to advertise network ! Disable automatic route summarization no auto-summary ! Designate passive interfaces passive-interface ( | default) ! Enable stub routing eigrp stub [receive-only | connected | static | summary] ! Statically identify neighoring routers neighbor Interface Configuration ! Configure manual summarization of outbound routes ip summary-address eigrp [] md5 ip authentication key-chain eigrp ip hold-time eigrp standby 1 priority standby 1 preempt standby 1 authentication md5 key-string standby 1 track standby 1 track decrement | learn} vrrp 1 priority vrrp 1 preempt vrrp 1 authentication md5 key-string vrrp 1 track decrement glbp 1 timers redirect glbp 1 priority glbp 1 preempt glbp 1 forwarder preempt glbp 1 authentication md5 key-string glbp 1 load-balancing glbp 1 weighting lower upper glbp 1 weighting track decrement ] dot1x test eapol-capable [interface ] dot1x re-authenticate interface v2.0 {permit | deny} [log] ! Modern syntax ip access-list standard { | } [] {permit | deny} [log] {permit | deny} [] [] [] ! Modern syntax ip access-list extended { | } [] {permit | deny} [] [] [] A single address Any address matched by the wildcard mask Match the specified IP DSCP fragments Check non-initial fragments {permit | deny} [log] ! Modern syntax ip access-list standard { | } [] {permit | deny} [log] {permit | deny} [] [] [] ! Modern syntax ip access-list extended { | } [] {permit | deny} [] [] [] A single address Any address matched by the wildcard mask Match the specified IP DSCP fragments Check non-initial fragments option Match the specified IP option precedence {0-7} Match the specified IP precedence ttl Match the specified IP time to live (TTL) TCP/UDP Port Definitions Equal to Not equal to Less than Greater than Matches a range of port numbers Miscellaneous Options Create a reflexive ACL entry time-range Enable rule only during the given time range Applying ACLs to Restrict Traffic interface FastEthernet0/0 ip access-group { | } {in | out} | ] show ip access-lists [ | ] show ip access-lists interface show ip access-lists dynamic show ip interface [ ] show time-range [ ] v2.0 Auto-RP Mapping Agent ip pim send-rp-discovery scope Auto-RP Candidate ip pim send-rp-announce BSR Candidate ip pim bsr-candidate BSR RP Candidate ip pim rp-candidate by Jeremy Stretch v2.0 frame-relay interface-dlci 101 ! interface Serial1/0.2 point-to-point description To Area 3 ip address 10.0.0.5 255.255.255.252 ip router isis isis circuit-type level-2-only frame-relay interface-dlci 102 ! router isis net 49.0001.0000.0000.00a1.00 frame-relay interface-dlci 101 ! interface Serial1/0.2 point-to-point description To Area 3 ip address 10.0.0.9 255.255.255.252 ip router isis isis circuit-type level-2-only frame-relay interface-dlci 103 ! router isis net 49.0002.0000.0000.00b1.00Text Text Text Text Text Text First Second Third Alpha Bravo Lorem ipsum dolor sit amet
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Level one
Level two
Level three
` tags
Use
tags
``echo `uname -a```
echo `uname -a` Code Blocks
Normal text #include
Normal text
#include Emphasis Emphasis Strong Strong Super emphasisSuper strongGoogle Google Google http://google.com Text TextText Text Text Text TextText Text Suppress [[wiki]] '''markup''' Text First Second Third Text Text Text Text Text TextTextText Text Term 1 Foo Item 2 Bar Item 3 Baz packet switching packet switched networking 802.3 http://google.com/ Google A photo ip nat translation udp-timeout ip nat translation max-entries Show mls qos v2.0>> l2.getlayer(2) code= 227 chksum= None unused= by Jeremy Stretch v1.0/- Matches TCP or UDP packets to/from a port in the given range less ] Matches 802.11 frames based on type and optional subtype vlan []] password version {1 | 2} pruning switchport voice vlan ! Trust ingress QoS markings mls qos trust cos ! Optionally pre-allocate power for the port power inline static [max ] 
