BGP1
来源:互联网 发布:曾荫权对抗中央 知乎 编辑:程序博客网 时间:2024/06/01 10:34
BGP Autonomous Systems :私有:64512-65535
--- An AS allows packets to transit through it to reach otherautonomous systems(for example ,it si a service provider). --- An AS has multiple connections to otherautonomous systems. --Routing policy and route selection for traffic entering andleaving the AS must be manipulated. BGPis not always appropriate,You do not have to use BGP if you haveone of the following conditions: ---Limited understanding of route filtering and BGP path-selectionprocess. ---A single connection to the Internet or another AS ---Lack of memory or processor power to handle constant updates onBGP routers. ---Reliable updates:runs on top of TCP (port 179) ---Incremental,triggered updates only ---Periodic keep-alive messages to verify TCP connectivity ---Rich metrics (called path vectors or attributes) ---Designed to scale to huge inter-networks(for example,theInternet)
BGP Databases(三张表) --List of BGP neighbors ---List of all networks learned from each neighbor ---Can contain multiple paths to destination networks ---Contains BGP attributes for each path ---List of best paths to destination networks
---Includes hold time and BGP router ID ---Information for one path only(could be to multiplenetworks) ---Includes path attributes and networks ---When error is detected ---BGP connection closed after message is sent
IBGP 通告路由
bgp router-id 4.4.4.4 bgp log-neighbor-changes neighbor 24.1.1.2 remote-as 1
bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 24.1.1.4 remote-as 4
BGP version 4, remote router ID4.4.4.4 BGP state = Established, up for00:02:00 Last read 00:00:03, last write 00:00:00,hold time is 180, keepalive interval is 60 seconds Neighbor sessions: 1 active, is notmultisession capable (disabled) Neighbor capabilities: Route refresh:advertised and received(new) Four-octets ASNCapability: advertised and received Address family IPv4Unicast: advertised and received Enhanced RefreshCapability: advertised and received MultisessionCapability: Stateful switchoversupport enabled: NO for session 1 Message statistics: InQ depth is 0 OutQ depth is 0 Sent Rcvd Opens: 1 1 Notifications: 0 0 Updates: 1 1 Keepalives: 3 3 Route Refresh: 0 0 Total: 5 5 Default minimum time between advertisementruns is 30 seconds
For address family: IPv4 Unicast Session: 24.1.1.4 BGP table version 1, neighbor version1/0 Output queue size : 0 Index 1, Advertise bit 0 1 update-group member Slow-peer detection is disabled Slow-peer split-update-group dynamic isdisabled Sent Rcvd Prefix activity: ---- ---- Prefixes Current: 0 0 Prefixes Total: 0 0 Implicit Withdraw: 0 0 Explicit Withdraw: 0 0 Used as bestpath: n/a 0 Used as multipath: n/a 0
Outbound Inbound Local Policy Denied Prefixes: -------- ------- Total: 0 0 Number of NLRIs in the update sent: max 0,min 0 Last detected as dynamic slow peer:never Dynamic slow peer recovered: never Refresh Epoch: 1 Last Sent Refresh Start-of-rib: never Last Sent Refresh End-of-rib: never Last Received Refresh Start-of-rib:never Last Received Refresh End-of-rib:never Sent Rcvd Refresh activity: ---- ---- Refresh Start-of-RIB 0 0 Refresh End-of-RIB 0 0
Address tracking is enabled, the RIB doeshave a route to 24.1.1.4 Connections established 1; dropped 0 Last reset never Transport(tcp) path-mtu-discovery isenabled Graceful-Restart is disabled
Packets received in fast path: 0, fastprocessed: 0, slow path: 0 fast lock acquisition failures: 0, slowpath: 0
router-id 2.2.2.2 network 2.2.2.0 0.0.0.255 area 0 network 12.1.1.0 0.0.0.255 area 0
bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 3.3.3.3 remote-as 1 neighbor 3.3.3.3 update-sourceLoopback0 neighbor 24.1.1.4 remote-as 4
router-id 1.1.1.1 network 12.1.1.0 0.0.0.255 area 0 network 13.1.1.0 0.0.0.255 area 0
router-id 3.3.3.3 network 3.3.3.0 0.0.0.255 area 0 network 13.1.1.0 0.0.0.255 area 0
bgp router-id 3.3.3.3 bgp log-neighbor-changes neighbor 2.2.2.2 remote-as 1 neighbor 2.2.2.2 update-sourceLoopback0
r RIB-failure, S Stale, m multipath, bbackup-path, f RT-Filter, x best-external, a additional-path, cRIB-compressed,
Network Next Hop MetricLocPrf Weight Path *> 4.4.4.0/24 0.0.0.0 0 32768 i
r RIB-failure, S Stale, m multipath, bbackup-path, f RT-Filter, x best-external, a additional-path, cRIB-compressed,
Network Next Hop MetricLocPrf Weight Path *> 4.4.4.0/24 24.1.1.4 0 0 4 i
r RIB-failure, S Stale, m multipath, bbackup-path, f RT-Filter, x best-external, a additional-path, cRIB-compressed,
Network Next Hop MetricLocPrf Weight Path * i 4.4.4.0/24 24.1.1.4 0 100 0 4 i
r RIB-failure, S Stale, m multipath, bbackup-path, f RT-Filter, x best-external, a additional-path, cRIB-compressed,
Network Next Hop MetricLocPrf Weight Path *>i 4.4.4.0/24 2.2.2.2 0 100 0 4 i
bgp router-id 1.1.1.1 bgp log-neighbor-changes neighbor aaa peer-group neighbor aaa remote-as 1 neighbor aaa update-source Loopback0 neighbor 2.2.2.2 peer-group aaa neighbor 3.3.3.3 peer-group aaa
bgp router-id 4.4.4.4 bgp log-neighbor-changes network 4.4.4.0 mask 255.255.255.0 neighbor 24.1.1.2 remote-as 1
bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor aaa peer-group neighbor aaa remote-as 1 neighbor aaa update-source Loopback0 neighbor aaa next-hop-self neighbor 1.1.1.1 peer-group aaa neighbor 3.3.3.3 remote-as 1 neighbor 3.3.3.3 update-sourceLoopback0 neighbor 3.3.3.3 next-hop-self neighbor 24.1.1.4 remote-as 4
bgp router-id 1.1.1.1 bgp log-neighbor-changes neighbor aaa peer-group neighbor aaa remote-as 1 neighbor aaa update-source Loopback0 neighbor 2.2.2.2 peer-group aaa neighbor 3.3.3.3 peer-group aaa
bgp router-id 3.3.3.3 bgp log-neighbor-changes neighbor aaa peer-group neighbor aaa remote-as 1 neighbor aaa update-source Loopback0 neighbor aaa next-hop-self neighbor 1.1.1.1 peer-group aaa neighbor 2.2.2.2 remote-as 1 neighbor 2.2.2.2 update-sourceLoopback0 neighbor 2.2.2.2 next-hop-self neighbor 5.5.5.5 remote-as 5 neighbor 5.5.5.5 ebgp-multihop 2 neighbor 5.5.5.5 update-sourceLoopback0
bgp log-neighbor-changes network 5.5.5.0 mask 255.255.255.0 neighbor 3.3.3.3 remote-as 1 neighbor 3.3.3.3 ebgp-multihop 2 neighbor 3.3.3.3 update-sourceLoopback0
AS号:公有 0-64511
AS号查询
http://www.cidr-report.org/as6447/autnums.html
BGP Path-Vector Routing
AS相当于一个大路由器
AS-by-AS
BGP Characteristics
BGP is most appropriate when at least one of thefollowing
conditions exists:
电信---网通
1、管理
2、OSPF 10000条,ISIS,20000条,internet 10几万条
3、BGP策略路由
4、 ---扩展应用,ipv4、ipv6、vpnv4、MPLS
BGP Characteristic(Count.)
BGP is a path-vector protocol with the follow
enhancements over distance vector protocols:
BGP Databases(三张表)
Neighbor table
BGP table(forwarding database)
IP routing table
不做负载均衡
AD
IBGP 200
EBGP 20
BGP Message Types
BGP defines the following message types:
Open
Keepalive
Update
Notification
_______________________________________________________________________
Explaining EBGP and IBGP
Peers = Neighbors
- A "BGP peer," also known as a "BGP neighbor," is a specificterm that is used for BGP speakers that have established a neighborrelationship
- Any two routers that have formed a TCP connection to exchangeBGP routing Information are called BGP peers or BGP neighbors.
External BGP
- When BGP is running between neighbors that belong to differentautonomous systems,it is called EBGP.
- EBGP neighbors,by default,need to be directly connected.
Internal BGP
- When BGP is running between neighbors within the save AS,it iscalled IBGP
- The neighbors do not have to be directly connected.
IBGP in a Transit AS (ISP)
- Redistributing BGP into an IGP (OSPF in this example) is notrecommended.
- Instead,run IBGP on all routers.
解决路由黑洞
1、物理线路FULL MESH
2、BGP邻居的FULL MESH
3、将BGP重分布到IGP(LAB)
4、MPLS( 最好的解决方案)
IBGP In a NonTransit AS
EBGP水平分割
不接收含有本AS号的BGP路由。
IBGP
By default,routers learned via IBGP are never propagatedto
other IBGP peers,so they need full-mesh IBGP
有条件的打破 IGBP水平分割。
IBGP
network hello邻居
EBGP
Neighbor
network
R4上的配置
router bgp 4
R2上的配置
router bgp 1
R4#show ip bgpsummary
BGP router identifier 4.4.4.4, local AS number 4
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
24.1.1.2 4 1 14 14 1 0 0 00:09:22 0
R2#show ip bgp neighbors
BGP neighbor is 24.1.1.4, remoteAS 4, external link
Connection state is ESTAB, I/O status: 1, unread input bytes:0
Connection is ECN Disabled, Mininum incoming TTL 0, OutgoingTTL 1
Local host: 24.1.1.2, Local port:179
Foreign host: 24.1.1.4, Foreign port:48615
Connection tableid (VRF): 0
Maximum output segment queue size: 50
Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)
Event Timers (current time is 0x31CD9):
Timer Starts Wakeups Next
Retrans 5 0 0x0
TimeWait 0 0 0x0
AckHold 4 2 0x0
SendWnd 0 0 0x0
KeepAlive 0 0 0x0
GiveUp 0 0 0x0
PmtuAger 0 0 0x0
DeadWait 0 0 0x0
Linger 0 0 0x0
ProcessQ 0 0 0x0
iss: 3917151808 snduna: 3917151946 sndnxt: 3917151946
irs: 1610121879 rcvnxt: 1610122017
sndwnd: 16247 scale: 0 maxrcvwnd: 16384
rcvwnd: 16247 scale: 0 delrcvwnd: 137
SRTT: 487 ms, RTTO: 3168 ms, RTV: 2681 ms, KRTT: 0 ms
minRTT: 7 ms, maxRTT: 1000 ms, ACK hold: 200 ms
Status Flags: passive open, gen tcbs
Option Flags: nagle, path mtu capable
IP Precedence value : 6
Datagrams (max data segment is 1460 bytes):
Rcvd: 11 (out of order: 0), with data: 5, total data bytes:137
Sent: 10 (retransmit: 0, fastretransmit: 0, partialack: 0,Second Congestion: 0), with data: 5, total data bytes: 137
TCP Semaphore 0xF49FCF8C FREE
R2#show tcp brief
TCB Local Address Foreign Address (state)
F1559798 24.1.1.2.179 24.1.1.4.48615 ESTAB
F4BFA5F8 2.2.2.2.17210 3.3.3.3.179 ESTAB
IBGP建议用环回接口建邻居。
更新源
NEI 24.1.1.2 NEI 24.1.1.4
US:24.1.1.4 US 24.1.1.2
NEI 3.3.3.3 NEI 2.2.2.2
US 12.1.1.2 US13.1.1.3
R2上的配置
router ospf 110
router bgp 1
R1上的配置
router ospf 1
R3上的配置
router ospf 110
router bgp 1
Example ebgp-multihop command
A路由器配置
router bgp 65102
neighbor 1.1.1.1 remote-as 65101
neighbor 1.1.1.1 update-source Loopback 0
neighbor 1.1.1.1 ebgp-multihop 2
ip route 1.1.1.1 255.255.255.255 192.168.1.18
ip route 1.1.1.1 255.255.255.255 192.168.1.34
B路由器配置
router bgp 65101
neighbor 2.2.2.2 remote-as 65102
neighbor 2.2.2.2 update-source Loopback 0
neighbor 2.2.2.2 ebgp-multihop 2
ip route 2.2.2.2 255.255.255.255 192.168.1.17
ip route 2.2.2.2 255.255.255.255 192.168.1.33
R4#show ip bgp
BGP table version is 2, local router ID is 4.4.4.4
Status codes: s suppressed, d damped, h history, * valid, >best, i - internal,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
*:为可用的,>:最优的路由
R2#show ip bgp
BGP table version is 2, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, >best, i - internal,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
R3#show ip bgp
BGP table version is 1, local router ID is 3.3.3.3
Status codes: s suppressed, d damped, h history, * valid, >best, i - internal,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
没有>:(不优的路由)
1、不会进路由表。
2、不会给其他BGP邻居传。
BGP路由优的条件:
1、同步(从IGP学习到/no syn)
2、下一跳
R3(config)#router bgp 1
R3(config-router)#no sy
R3(config-router)#no synchronization
R2(config-router)#neighbor 3.3.3.3next-hop-self
R3#show ip bgp
BGP table version is 2, local router ID is 3.3.3.3
Status codes: s suppressed, d damped, h history, * valid, >best, i - internal,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
BGPSynchronization
Synchronization rule:Do not use or advertise to an externalneighbor a route learned by IBGP until a
matching route has been learned from an IGP
-
Ensures consistency of information throughout the AS -
Safeto have it off only if all routers in the transit path in the ASare running full-mes IBGP:off by default in Cisco software release12.2(8)
Router(config-router)#
no synchronization
-
Disables BGP synchronization so that a router will advertise routesin IGP without learning them in an IGP
Router (config-router)#
synchronization
- Enables BGP synchronization so that a router will not advertiserouters in BGP until it learns them in an IGP
Using a peer group
Router(config-router)#
neighbor peer-group-name peer-group
- This command creates a peer group.
Router(config-router)#
neighbor ip-address peer-grouppeer-group-name
- This command defines a template with parameters set for a groupof neighbors instead of individually.
- This command is useful when many neighbors have the sameoutbound policies.
- Members can have a different inbound policy.
- Updates are generated once per peer group.
- Configuration is simplified.
R1#show run | b r b
router bgp 1
R4#show run | b r b
router bgp 4
R2#show run | b r b
router bgp 1
R1#show run | b r b
router bgp 1
R3#show run | b r b
router bgp 1
!
R5#show run | b r b
router bgp 5
!
阅读全文
0 0
- BGP1
- 正则表达式(python为纲)
- Redistribute/Route-map
- Maximum Binary Tree问题及解法
- vc下文件下载的两种方法
- winserver 2008sp2 下 apache&nbsp…
- BGP1
- http下载大文件测试
- 求大佬搞定,严重: Exception sending context destroyed event to listener instance of class
- 微信小程序开发常见问题分析
- ubuntu 16.04安装smba服务
- 学习maven的使用
- TCP/IP详解--举例明白发送/接收缓冲区、滑动窗口协议之间的关系
- EtherPeek NX
- Android 实现悬浮的几种方式(二)HeaderView显示隐藏