Código fonte Wiki de BGP

Última modificação por Jean Franco em 2022/06/23 22:09
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1 == The Prefix Lists ==
2
3 The prefix lists are used to control what routes you get from your ISP, as well as the ones you send (announce).
4
5 {{code language="none"}}
6 policy {
7 prefix-list BGP-ISP-From {
8 rule 10 {
9 action permit
10 le 24
11 prefix 0.0.0.0/0
12 }
13 }
14 prefix-list BGP-ISP-To {
15 rule 10 {
16 action permit
17 prefix 192.0.2.0/24
18 }
19 }
20 prefix-list6 BGP-ISPv6-From {
21 rule 10 {
22 action permit
23 le 64
24 prefix 0::/0
25 }
26 }
27 prefix-list6 BGP-ISPv6-To {
28 rule 10 {
29 action permit
30 le 48
31 prefix 2001:DB8::/32
32 }
33 }
34 }
35 {{/code}}
36
37 The -From prefix lists are for routes you receive (imported) from your ISP, while the -To lists are for routes being exported (announced) to your provider. In the case of IPv4, the smallest globally accepted size most if not all providers announce is /24. For IPv6, the smallest globally accepted size is /48.
38
39 'le' means any prefix smaller (ie: 'le 48' won't allow a /64 IPv6 prefix from your ISP's routing table, but it will allow a /32). 'ge' means any prefix greater (ie: 'ge 56' won't allow a /48, but will allow a /56, /64, or even /128).
40
41 In the above examples, 192.0.2.0/24 is your IPv4 netblock, and 2001:DB8::/32 is your IPv6 one. 0.0.0.0/0 and 0::/0 means match all.
42
43 === Route Maps ===
44
45 While you can just use prefix lists with BGP to control routes imported and exported, route maps give you much more flexibility and control, and can even include AS path matching.
46
47 {{code language="none"}}
48 policy {
49 route-map BGP-ISPv6-From {
50 rule 10 {
51 action permit
52 match {
53 ipv6 {
54 address {
55 prefix-list BGP-ISPv6-From
56 }
57 }
58 }
59 }
60 }
61 route-map BGP-ISPv6-To {
62 rule 10 {
63 action permit
64 match {
65 ipv6 {
66 address {
67 prefix-list BGP-ISPv6-To
68 }
69 }
70 }
71 }
72 }
73 route-map BGP-ISP-From {
74 rule 10 {
75 action permit
76 match {
77 ip {
78 address {
79 prefix-list BGP-ISP-From
80 }
81 }
82 }
83 }
84 }
85 route-map BGP-ISP-To {
86 rule 10 {
87 action permit
88 match {
89 ip {
90 address {
91 prefix-list BGP-ISP-To
92 }
93 }
94 }
95 }
96 }
97 }
98 {{/code}}
99
100 Like the prefix lists, -To and -From are your specific directions in and out (import and export). They're pretty self explanatory and reference the prefix lists used before.
101
102 BGP Protocol Information
103
104 {{code language="none"}}
105 protocols {
106 bgp 65501 {
107 address-family {
108 ipv6-unicast {
109 network 2001:DB8::/32 {
110 }
111 }
112 }
113 neighbor 100.64.100.1 {
114 remote-as 65502
115 route-map {
116 export BGP-ISP-To
117 import BGP-ISP-From
118 }
119 soft-reconfiguration {
120 inbound
121 }
122 update-source 100.64.100.2
123 }
124 neighbor fd00::1 {
125 address-family {
126 ipv6-unicast {
127 route-map {
128 export BGP-ISPv6-To
129 import BGP-ISPv6-From
130 }
131 }
132 }
133 remote-as 65502
134 soft-reconfiguration {
135 inbound
136 }
137 update-source fd00::2
138 }
139 network 192.0.2.0/24 {
140 }
141 parameters {
142 router-id 100.64.100.2
143 }
144 redistribute {
145 connected {
146 }
147 kernel {
148 }
149 static {
150 }
151 }
152 }
153 }
154 {{/code}}
155
156 In the above example, our local router has the IPv4 address of 100.64.100.2 and the IPv6 address of fd00::2 with an ASN of 65501. The BGP enabled router on our ISP side is 100.64.100.1 and fd00::1 with an ASN of 65502. We are assuming that our routers are connected over a non-shared link within one hop. If the BGP router is more than one hop away, you need to configure 'ebgp-multihop' with the appropriate amount of hops away your ISP's router is.
157
158 Show BGP information:
159
160 {{code language="none"}}
161 user@router1:~$ show ip bgp neighbor
162 BGP neighbor is 100.64.100.2, remote AS 65502, local AS 65501, external link
163 BGP version 4, remote router ID 100.64.100.2
164 BGP state = Established, up for 01w0d05h
165 Last read 01w0d05h, hold time is 90, keepalive interval is 30 seconds
166 Neighbor capabilities:
167 Route refresh: advertised and received (old and new)
168 4-Octet ASN Capability: advertised and received
169 Address family IPv4 Unicast: advertised and received
170 Address family IPv4 Multicast: received
171 Received 2838376 messages, 0 notifications, 0 in queue
172 Sent 20788 messages, 0 notifications, 0 in queue
173 Route refresh request: received 0, sent 0
174 Minimum time between advertisement runs is 30 seconds
175 Update source is 100.64.100.1
176 For address family: IPv4 Unicast
177 BGP table version 6603726, neighbor version 6603716
178 Index 2, Offset 0, Mask 0x4
179 Inbound soft reconfiguration allowed
180 Community attribute sent to this neighbor (both)
181 Inbound path policy configured
182 Outbound path policy configured
183 Route map for incoming advertisements is *BGP-ISP-From
184 Route map for outgoing advertisements is *BGP-ISP-To
185 688930 accepted prefixes
186 1 announced prefixes
187
188 Connections established 1; dropped 0
189 External BGP neighbor may be up to 1 hops away.
190 Local host: 100.64.100.2, Local port: 60803
191 Foreign host: 100.64.100.1, Foreign port: 179
192 Nexthop: 100.64.100.1
193 BGP connection: shared network
194
195 BGP neighbor is fd00::1, remote AS 65502, local AS 65501, external link
196 BGP version 4, remote router ID 100.64.100.1
197 BGP state = Established, up for 01w0d05h
198 Last read 01w0d05h, hold time is 180, keepalive interval is 60 seconds
199 Neighbor capabilities:
200 Route refresh: advertised and received (old and new)
201 4-Octet ASN Capability: advertised and received
202 Address family IPv4 Unicast: advertised
203 Address family IPv6 Unicast: advertised and received
204 Received 686685 messages, 0 notifications, 0 in queue
205 Sent 10394 messages, 0 notifications, 0 in queue
206 Route refresh request: received 0, sent 0
207 Minimum time between advertisement runs is 30 seconds
208 Update source is fd00::2
209 For address family: IPv4 Unicast
210 BGP table version 6603726, neighbor version 6603716
211 Index 1, Offset 0, Mask 0x2
212 Inbound soft reconfiguration allowed
213 Community attribute sent to this neighbor (both)
214 0 accepted prefixes
215 0 announced prefixes
216
217 For address family: IPv6 Unicast
218 BGP table version 858622, neighbor version 858620
219 Index 1, Offset 0, Mask 0x2
220 Community attribute sent to this neighbor (both)
221 Inbound path policy configured
222 Outbound path policy configured
223 Route map for incoming advertisements is *BGP-ISPv6-From
224 Route map for outgoing advertisements is *BGP-ISPv6-To
225 49892 accepted prefixes
226 1 announced prefixes
227
228 Connections established 1; dropped 0
229 Local host: fd00::2, Local port: 179
230 Foreign host: fd00::1, Foreign port: 8044
231 Nexthop: 100.64.100.1
232 Nexthop global: fd00::1
233 BGP connection: shared network
234 {{/code}}
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