BGP-advertising

Similar Questions

• Change of advertising for the BGP subnet

  Probably a simple question, but my skills BGP are almost nothing... apologies in advance.

  Scenario:

  CompanyABC has a 22 1.1.0.0 subnet.  The 22 full announced out of CorpOffice1 to isps1.  There is a roadmap set up that uses a prefix list to announce the outgoing subnets.  Below is an example config:

  BGP:

  router bgp 35555

  changes of the next newspaper

  Remote 2.2.2.2 a neighbor - like 5555

  2.2.2.2 neighbor activate

  neighbor 2.2.2.2 soft-reconfiguration inbound
  2.2.2.2 a neighbor ISP1_5555_out map out route

  Map of the route:

  ISP1_5555_out allowed 10 route map
  match ip address prefix-list ISP1_Primary

  List of prefixes:

  IP-list of prefixes ISP1_Primary seq 10 permit 1.1.0.0/22

  Lets say that CompanyABC also has another office which is also served by isps1.  They want to divide the 22 subnet so that the first 3 subnets (1.1.0.0,1.1.1.0 and 1.1.2.0) are always announced to CorpOffice1, but they want to configure BGP with isps1 to CorpOffice2 and announce only the 1.1.3.0 subnet from there.

  Questions:

  The configuration change is not as simple as changing the prefix-list to the CorpOffice1 to announce the 3 24 subnets and configure a BGP configuration similar to CorpOffice2, but only the 1 24 subnet advertising?

  Changing the configuration to CorpOffice1 would require coordination with isps1 to make this change?

  (Should of course coordinate with isps1 configure BGP CorpOffice2 to announce the second subnet.)

  What is time of reconfiguration CorpOffice1 stop/impact?

  Thanks in advance, guys.

  Yes you can do as you said. You can use following the procedure-

  -Come three/24 prefixes of CorpOffice1.

  -Change the prefix-list out route-map to allow three 24 prefixes.

  -Ask the ISP to accept these prefixes. ISP must have applied inbound route-map to have control on the prefixes that you are advertising. It may be in a format like "prefix ip allowed list of 24 1.1.0.0/22" or may be just allowed 22 prefix. Therefore, confirmation with the ISP and this route-map change may be required.

  -Once the ISP confirms that they are open/24 prefixes and advertising to the internet, you can stop advertising 22 prefix. Confirm if 24 prefixes are announced to internet or not, you can connect to any global server and look for your bgp route prefixes.

  -Also, as soon as you stop the advertising/22 prefix, check if you are able to reach internet or not. If this is not the case, take a source based traceroute results and then start advertising again 22 prefix and troubleshoot it ISP below.

  -Note pls useful messages-

  Kind regards

  Assani

• Questions about N3024 switch by default - originate BGP

  Here is the configuration of the two switches.  I set up and rising BGP, passing of prefixes.  I want 1 switch to send a default gateway to switch 2 and have the default installation of command on the next statement are created.  I don't see the 0.0.0.0 route by default in the show ip bgp sum command, but which is detailed in the configuration guide.  However, I don't see a default route 0.0.0.0 in the routing table for switch 2 at all and an error message that there is no default route available.  Would I be missing here?

  Config is below:

  SWITCH 1

   

   

   

   

  Configure

  VLAN 50

  output

  VLAN 50

  name "switchtest".

  output

  hostname "Switch_1.

  location 1/0 1! Dell network N3024

  battery

  1 1 member! N3024

  output

  IP routing

  !

  loopback interface 1

  IP 10.0.0.1 address 255.255.255.255

  IP ospf area 0

  output

  interface vlan 1

  DHCP IP address

  output

  interface vlan 50

  172.16.0.1 IP address 255.255.255.252

  IP ospf area 0

  output

  router ospf

  router ID 10.0.0.1

  10.0.0.1 network 255.255.255.255 area 0

  network 172.16.0.0 255.255.255.252 area 0

  output

  !

  item in gi1/0/1 interface

  Description 'Switch '.

  switchport access vlan 50

  output

  Server SNMP engineid local 800002a203f8b1566f36c4

  router bgp 65001

  router BGP 10.0.0.1 ID

  172.168.0.0 netmask 255.255.255.252

  10.0.0.1 netmask 255.255.255.255

  172.16.0.2 neighbor remote - as 65002

  neighbor 172.16.0.2 are created by default

  output

  output

  Switch_1 #show ip bgp

  BGP table version is 7, local router ID is 10.0.0.1

  Status codes: s removed, * valid, > best, i - internal

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

  Network Next Hop metric LocPref path origin

  ------------------- ---------------- ---------- ---------- ------------- ------

  * > 172.16.0.0/30 172.16.0.2 1 100 65002 I

  * > 192.168.100.0/30 172.16.0.2 1 100 65002 I

  * > I have 10.0.0.1/32 0.0.0.0 1 100 I

  * > 10.0.0.2/32 172.16.0.2 1 100 65002 I

  Switch_1 #show ip bgp sum

  IPv4 routing... Enable

  BGP Admin Mode... Enable

  BGP router ID... 10.0.0.1

  Local AS number... 65001

  Traps ......................................... Disable

  Maximum paths... 1

  Maximum paths IBGP... 1

  Default Keep Alive Time... 30

  Default hold time... 90

  Number of entries of network... 4

  Number of PATHS... 1

  Default metric... Not configured

  Advertise default route... NO.

  Redistribution:

  Dist metric list of source route map

  --------- ---------- -------------------------------- --------------------------------

  Neighbor ASN MsgRcvd MsgSent State down time Pfx Rcvd

  ---------------- ----- -------- -------- ------------- -------------- ---------

  172.16.0.2 65002 78 82 ESTABLISHED 0:00:23:24 3

  Switch_1 #show ip route

  The traffic code: R - RIP derived, O - OSPF derived, C - connected, S - static

  B - Derived E - from outside, AI - BGP OSPF Inter zone

  E1 - OSPF external Type 1, E2 - OSPF external Type 2

  N1 - OSPF NSSA external Type 1, N2 - OSPF NSSA external Type 2

  S U - unnumbered Peer, L - flight road

  * Indicates the best route (the lowest metric) for the subnet.

  No default gateway is configured.

  *10.0.0.1/32 C [0/1] directly connected, Lo1

  B *10.0.0.2/32 [20/1] via 172.16.0.2, Vl50

  10.0.0.2/32 [110/11] via 172.16.0.2, Vl50

  *172.16.0.0/30 C [0/1] directly connected, Vl50

  B 172.16.0.0/30 [20/1] via 172.16.0.2, Vl50

  B *192.168.100.0/30 [20/1] via 172.16.0.2, Vl50

  192.168.100.0/30 [110/20] through 172.16.0.2, Vl50

  SWITCH 2

  Configure

  VLAN 50 100

  output

  VLAN 50

  name "SwitchTest".

  output

  VLAN 100

  name of the 'Switch '.

  output

  hostname "Switch_2".

  location 1/0 2. Dell network N3024F

  battery

  1 2 Member! N3024F

  output

  IP routing

  !

  loopback interface 0

  output

  !

  loopback interface 1

  10.0.0.2 IP address 255.255.255.255

  output

  interface vlan 1

  DHCP IP address

  output

  interface vlan 50

  IP 172.16.0.2 255.255.255.252

  IP ospf area 0

  output

  interface vlan 100

  IP 192.168.100.1 255.255.255.252

  output

  router ospf

  router ID 10.0.0.2

  10.0.0.2 network 255.255.255.255 area 0

  network 172.16.0.0 255.255.255.252 area 0

  network 192.168.100.0 255.255.255.252 area 0

  output

  !

  interface item in gi1/0/23

  switchport access vlan 100

  output

  !

  interface item in gi1/0/24

  Description 'Switch '.

  switchport access vlan 50

  output

  Server SNMP engineid local 800002a203f8b156530097

  router bgp 65002

  router BGP 10.0.0.2 ID

  172.16.0.0 netmask 255.255.255.252

  192.168.100.0 netmask 255.255.255.252

  10.0.0.2 netmask 255.255.255.255

  neighbor remote - as 65001 172.16.0.1

  output

  output

  Switch_2 #show ip bgp

  Version of BGP table is 9, local router ID is 10.0.0.2

  Status codes: s removed, * valid, > best, i - internal

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

  Network Next Hop metric LocPref path origin

  ------------------- ---------------- ---------- ---------- ------------- ------

  * > I have 172.16.0.0/30 0.0.0.0 1 100 I

  * > I have 192.168.100.0/30 0.0.0.0 1 100 I

  * > 10.0.0.1/32 172.16.0.1 1 100 65001 I

  * > I have 10.0.0.2/32 0.0.0.0 1 100 I

  Switch_2 #show ip bgp sum

  IPv4 routing... Enable

  BGP Admin Mode... Enable

  BGP router ID... 10.0.0.2

  Local AS number... 65002

  Traps ......................................... Disable

  Maximum paths... 1

  Maximum paths IBGP... 1

  Default Keep Alive Time... 30

  Default hold time... 90

  Number of entries of network... 4

  Number of PATHS... 1

  Default metric... Not configured

  Advertise default route... NO.

  Redistribution:

  Dist metric list of source route map

  --------- ---------- -------------------------------- --------------------------------

  Neighbor ASN MsgRcvd MsgSent State down time Pfx Rcvd

  ---------------- ----- -------- -------- ------------- -------------- ---------

  172.16.0.1 65001 83 82 ESTABLISHED 0:00:24:32 1

  Switch_2 #show ip route

  The traffic code: R - RIP derived, O - OSPF derived, C - connected, S - static

  B - Derived E - from outside, AI - BGP OSPF Inter zone

  E1 - OSPF external Type 1, E2 - OSPF external Type 2

  N1 - OSPF NSSA external Type 1, N2 - OSPF NSSA external Type 2

  S U - unnumbered Peer, L - flight road

  * Indicates the best route (the lowest metric) for the subnet.

  No default gateway is configured.

  B *10.0.0.1/32 [20/1] via 172.16.0.1, Vl50

  10.0.0.1/32 [110/11] via 172.16.0.1, Vl50

  *10.0.0.2/32 C [0/1] directly connected, Lo1

  *172.16.0.0/30 C [0/1] directly connected, Vl50

  *192.168.100.0/30 C [0/1] directly connected, Vl100

  Switch_2 #show ip route 0.0.0.0

  The traffic code: R - RIP derived, O - OSPF derived, C - connected, S - static

  B - Derived E - from outside, AI - BGP OSPF Inter zone

  E1 - OSPF external Type 1, E2 - OSPF external Type 2

  N1 - OSPF NSSA external Type 1, N2 - OSPF NSSA external Type 2

  S U - unnumbered Peer, L - flight road

   * Indicates the best route (the lowest metric) for the subnet.

  No default gateway is configured.

  No route found.

  Solution:

  Dell switches need to be turned on in the config.

  router bgp * AS number *.

  default-information originate always

• BGP configuration

  Hi all

  Please can someone help me understand this concept...

  Let me show you the scenario

  a single MPLS of ISP connection come to my router and my router in the DMZ servers

  I have to connect to the remote server to my server DMZ

  The ISP gave me the details of BGP configure

  now what do I Route my private network for remote servers...

  I run NAT on my router to go through the ISP connection... now I can ping to the gateway of the ISP and can see all the router in table bgp #sh

  is this correct or I need to directly transfer traffic from the internal network of ISP through BGP... or

  Do I have to create Tunnels... If the Tunnels are necessary then I need to know the remote desktop

  

  Thank you very much in advance

  You have 1 site that has a circuit of mpls and the other doesn't, or go in the same provider and SPLM on both sides? If you have mpls on both sides by the same provider, it should be as easy as peering with the supplier with bgp on both sides and advertising then your internal subnets. If you have the public internet between you, you will need tunnels of lan-to-lan creat between two routers. Here is a guide to help you to do:

  http://www.Cisco.com/en/us/Tech/tk583/TK372/technologies_configuration_example09186a0080094634.shtml

  HTH,
  John

  Please note all useful messages *.

• Original Site BGP attribute

  Dear friends,

  I tried to get a good understanding of the Site of origin of BGP attribute (not so EIGRP). I understand his idea and its impact, but there is a problem that I couldn't wrap my head around yet.

  Quoting RFC 4364, Section 8:

                       We add one more restriction on the distribution of    routes from PE to CE: if a route's Site of Origin attribute    identifies a particular site, that route must never be redistributed    to any CE at that site. 

  My understanding of this statement is that a site must be identifiable by a given value of the attribute of so, or in other words, there should be a way to assign a specific value of the attribute so to the entire site. Then, knowing the value of the so for the entire site, a route once appeared on this site should never be announced to him.

  This is where my problems start. We know that there is not a strict mapping one to one between a site and a VRF. A site can consist of one or several VRF and is not actually represented by a single object in the IOS - it's rather a simple collection of VRF who share routing information in such a way that for mutual communication, the use of the vertebral column is not required. There is no representation of the site as a single object in the IOS and there is therefore no way to assign a particular site so as a whole. In addition, the attribute so is not yet configured on a basis of by-VRF, instead, it is pushed on the individual courses from USING a road map or a per neighbor configuration. What is so attribute on a given prefix from, then? I simply do not see how a whole VRF or an entire site is assigned its own value of so unique for comparison purposes, in a manner similar to the assignment of identifiers of road or road of targets based on per VRF.

  So my question is: If the attribute so is pushed on routes from one THIS and these routes are announced to an another EP on the same site, how is the EP another knows the correct value of the site of the so so that it can compare to the so on prefixed receipt and not advertise routes to the site they came from? The VRF simply "inherits" the individual itineraries so as they are received and processed by a road-map set- ting so?

  Any help and clarification is appreciated!

  Best regards

  Peter

  Hi Peter,.

  So for BGP is "related" to THAT neighbor. Thus, when a prefix must be announced to a neighbor, we check the so of the prefix with the so of the BGP neighbor. For anything else, he is bound to the interface.

  The configuration can be done in four different ways (the setting of the so and the verification of the so is related to that):

  (1) ' road-map in ' on what neighboring BGP command

  (2) directly on the order of CE BGP neighbor

  (3) plan of the site on the interface of the VRF and redistribution of the (static) IGP into BGP routes and (static), IGP point to this interface

  (4) plan of the site on the command interface and network VRF

  General principle (but you know it):

  http://www.Cisco.com/en/us/partner/docs/iOS/ios_xe/iproute_bgp/configuration/guide/irg_neighbor_soo_xe.html

  With the help of a roadmap and setting different for different prefixes from the same neighbor BGP SoO doesn't make much sense, so I guess that we were never bothered by possible nonuniqueness in the configuration when you look at what a 'site' is.

  Thank you

  Luke

• DMVPN BGP and EIGRP

  I am in the initial phase of research DMVPN.  We currently have an MPLS network running BGP.  Each site has Internet at home as well as a VPN site-to-site is built on the router and talks to an ASA when the SPLM fails.

  I want to implement DMVPN to do away with the site to site VPN and ASA.  I'm going to run EIGRP on routers to connect DMVPN.  Are there any good whitepapers on BGP as the main path and by EIGRP on the DMVPN as a backup?  Or no focus on a general config?

  Thank you

  It's really the main issue.

  With your configuration DMVPN roads will be internal EIGRP of an advertisement of 90, so your default DC prefer DMVPN on MPLS, which is exactly what you don't want.

  There are several ways around this as summarizing through DMPVN, redistribution connected on the sites of the branch in EIGRP so roads DMVPN are external as well and then changing measures etc.

  The other alternative I have ever done so it's for your information is really Cisco have what is called a solution IWAN where DMVPN is performed everywhere that is, even through the MPLS network.

  That would solve your problem of external routes internal EIGRP but IWAN vs is much more than just that, even if you do not need necessarily to implement the entire solution at a time.

  I just thought that it should be mentioned, and if you want more information on this I can direct you to the design guide.

  Jon

• Duplicate BGP AS path

  Hello guys,.

  Today at awkward work something caught my attention.

  The situation returns to BGP, when I run the command sh ip bgp, the output gives me this:

  RT52162 #sh ip bgp
  Version of BGP table is 56, local router ID is 10.10.0.16
  Status codes: deleted, cushioning d s, history of h, * valid, > best, i - internal.
  r SIDE-failure, stale S
  Source codes: i - IGP, e - EGP,? -incomplete

  Network Next Hop path metrics LocPrf weight
  * 0.0.0.0 172. **. 161 50 0 15 * 15 * 5 5 65010?
  *>                                 172.**.***.169                              0          15**5 65010 ?
  *> 10.**.0.16/32        0.0.0.0                                            0            32768 ?
  *> 10.**.0.0/16          0.0.0.0                                            0            32768 ?

  The part "BOLD" of the output is exactly the same thing, and this connection works on ATM.

  I can't understand this question, so if someone could explain to me why this is happening or how can we solve it, I have other sites configured the with the same configuration and it gives me the same exact result.

  Hello

  The nearby 172.xxx.xxx.161 done AS_PATH adding by adding at the beginning of his time number one DID when advertising the default route so it is considered to be a neighbor of backup.

  Concerning

  Alain

• BGP

  Hi all

  We have a customer who has formed the BGP relationship with one of the neighbor ISP. The way they put in place is, they are just nearby and they advertise only their subnet but do not receive all of the ISP.

  They just use static to point to ISP route.

  Can someone please advise, why it is necessary to do so? (No advantage)

  They can't just point to ISP using a static route without having to buy BGP AS? (If say save money)

  Can they just get the ISP routing table?

  I know they are different thing to consider.

  (1) router can handle the load?

  (2) have double links?

  But apart from this no specific advantage? Please advice.

  Thank you

  Hello

  Customer must have session BGP with ISP to announce its internal network and the networks of his client to the outside world. Otherwise to buy ip pool of the psi and PSI would BGP origination and the advertising of this ip pool. Problem is in this case, when the customer changes service provider, it would need to re - allocate ip addresses in its network given by new ISP. It's not easy and it's pain.

  For outbound traffic, if the customer is having a single link upstream to the ISP-1, no point of taking the route table full, instead it may have the default route to push all traffic to ISP - 1. Now this default route will be charged via BGP static route or service provider. Customer must be redistribute static PGI to make it available to the other routers on the network.

  -Pls remember messages useful rate.

  Kind regards
  Assani

• Metric IGP into BGP MED copied.

  Hi all

  I have a problem of BGP that inherits from my IGP metric value in its attribute MED. I have an EBGP peering with my client. I send only specific to my counterpart ebgp routers using network commands in BGP.i receive the prefixes by ospf in my table.i itinerary not to redistribute these routes to bgp, but network command allows to advertise in BGP.

  My question is when these prefixes are to be sent to my EBGP peer, he takes the metric value of the IGP and fasten it as value MED. This is an impact on the choice of the route of my client which is in a MPLS cloud. Is this a normal behavior... or how to stop the BGP will send this MED value.

  Kind regards

  Jean-Pierre

  Discovering that you send to an eBGP neighbor, drugs even if you never wanted, can be a surprise, but it happens. If the injected into BGP route (either using 'network' or 'redistribute' order) comes from an IGP, MED is derived from the IGP metric, and the road was announced to a neighboring eBGP with this med. Guiseppe has already provided a solution for your problem. Another option is to inject routes into BGP using the command 'aggregate-address', in which case MED is not defined. Personally, I prefer the configuration command "network" combined with the solution that Giuseppe suggested.

• Why "bgp bestpath missing-as-worst med" command does not produce the desired result?

  Can dear all, someone tell me why "bgp bestpath missing-as-worst med" command does not produce the desired result?
  And I use GNS3 to this practice, the IOS Version: 12.4 (3)
  TKS...

  Back to the beginning:
  192.168.23.0/24 192.168.12.0/24
  RA(F0/0)-(f0/0) RB (s2/0) - RC (s2/0)
  [AS1]                    [AS2]                    [AS3]

  Configuration:
  * RA *:
  A #do sh run (config - router). b r b
  router bgp 1
  no synchronization
  The log-neighbor BGP-changes
  1.1.1.0 netmask 255.255.255.0
  192.168.12.2 neighbor remote-2
  setmed map of nearby route 192.168.12.2 out
  No Auto-resume

  IP route 1.1.1.0 255.255.255.0 Null0

  setmed allowed 10 route map
  the metric value 20

  * RB *:
  B (config - router) #do sh run | b r b
  router bgp 2
  no synchronization
  BGP always-compare-med
  The log-neighbor BGP-changes
  BGP bestpath missing-as-worst med
  neighbor 192.168.12.1 distance-1
  neighbour 192.168.23.3 distance-3
  No Auto-resume

  * RC *:
  C (config - router) #do sh run | b r b
  router bgp 3
  no synchronization
  The log-neighbor BGP-changes
  1.1.1.0 netmask 255.255.255.0
  neighbour 192.168.23.2 distance-2
  No Auto-resume

  IP route 1.1.1.0 255.255.255.0 Null0

  But when I checked out table RB bgp, as below:

  B (config - router) #do sh ip bgp
  BGP table version is 2, local router ID is 192.168.23.2
  Status codes: deleted, cushioning d s, history of h, * valid, > best, i - internal.
  r SIDE-failure, stale S
  Source codes: i - IGP, e - EGP,? -incomplete
  Network Next Hop path metrics LocPrf weight
  * > 1.1.1.0/24 192.168.23.3 0 0 3 I
  *                          192.168.12.1            20                         0  1 i

  The prefix is assigned a MED of 0, but also the best path value when I use "bgp bestpath missing-as-worst med" in how to configure bgp... :-(

  Please take a look at the discussion on the configuration of drugs to an eBGP neighbor:

  https://supportforums.Cisco.com/thread/343397?TSTART=0

  Note that BGP MED is set to 0 even if the injected BGP route from a connected route.

  The first time I came across this problem sending MED was there in a picture of 5-6 years service provider. Routes were injected into BGP with the command 'network', has been validated by OSPF routes or static to null0. Involuntary consignment of drugs was mess with load balancing between 2 links of our inbound traffic from the same upstream service provider.

  Also note that if a route is learned via iBGP, border router removes MED before the road to advertising for an eBGP peers (i.e. the above comments apply a when a route is injected locally into the border and then router BGP sent to an eBGP peer).

  I don't know what the cause of the problem that you said in your last post. It delivers last for a long time or that it does not change after a while?

  p.s. Sorry, I edited post because I said "iBGP" instead of "eBGP" at some point.

• BGP path selection

  Hello

  in my bgp table, I have two paths to the defaultroute:

  65052:420:0.0.0.0/0, version 4803 BGP routing table entry

  Paths: (2 available, excellent #2, table vkb)

  Not announced in any position

  Local

  172.16.24.2 (98 metric) of 172.16.24.2 (172.16.24.62)

  Incomplete 755968, metrics, localpref 100 original, valid, internal

  Community: RT:65052:420 0 x 8800: 0:8212 0 x 8801: 100:131072 0 x 8802: 65283:624896 0 x 8803: 65281:1500 0 x 8804: 0:2886794964 0 x 8805: 3:0,.

  label MPLS/exit nolabel/1602

  Local

  172.16.24.1 (99 metric) of 172.16.24.1 (172.16.24.61)

  Incomplete metric, original 755712, localpref 100, valid, internal, best

  Community: RT:65052:420 0 x 8800: 0:8211 0 x 8801: 100:130816 0 x 8802: 65282:624896 0 x 8803: 65299:1500 0 x 8804: 0:2886794963 0 x 8805: 3:0,.

  label MPLS/exit nolabel/1410

  Why is the way to selected 172.16.24.1 even if the igp metric to 172.16.24.2 is 98 and 172.16.24.1 is 99!

  so the way to 172.16.24.2 is better (98).

  I am a redistribution of eigrp to the mpls backbone

  thx for the answer

  Hello

  MED for the preferred route is lower than the other. MED is regarded as to the cost of the IGP for the advertising router.

  HTH.

  -Rob

• BGP community send - how does it work?

  Hi guys,.

  I hope that if anyone can help me understand how to send a community attributes work between ISP?

  We have an internet connection to multihomed with two Internet service providers of peering with two local routers (R01 - INT and INT - R02) and we are prefer isps1 on the other. Please attached flowchart along.

  We run iBGP between the local routers (R01 - INT and INT - R02) and R01 has a higher local preference which is looked at with isps1 and R02 has lower local preference which is looked at with ISP2.

  We are a consignment attribute ISP2 community with advertising prefixes they use to manipulate the routing. I have also read on their site with this community attribute, they alter the local preference of roads so that it is less than one received a counterpart road but is not less than a transit provider.

  I understand that they will lower the local on their router preference so that it is not preferred but how IPS2 say other ISPS is not the way through their network if you go to those specific prefixes.

  Really appreciate your help.

  Thanks in advance.

  Jay

  Hello

  In my humble OPINION, they can manipulate BGP attributes again (BY adding or MED, for example) or even to use the special communities agreed with their neighbour ISPS in advertising prefixes to them?

  Best regards

  Milan

• Difference between are created by default and 0.0.0.0 network in BGP

  Hello

  Please I need someone to clarify what is the difference between the command "come from default" and "network 0.0.0.0 - ip route 0.0.0.0 0.0.0.0 null0" commands. I see both serve the same purpose by a default route to a counterpart of the advertising, but at the same time, I feel a difference on them.

  THX

  Kind regards

  B....

  Dear friends,

  Lingam summarizes the options to inject the default route in BGP very well. Thank you!

  In addition, let me point out a few differences between these approaches.

  The default information is created, redistribution from a different source and the network 0.0.0.0 are all similar in the resulting effect: they will inject the default route in BGP RIBS and it will be announced to all the BGP neighbors. The difference is originally from the default route that is injected into BGP:

  • default information is created causes the default route generated artificially and injected in the BGP RIB, launch to know if it is present in the routing table.
  • Redistribution and 0.0.0.0 network will inject the default route in BGP only if the default route is currently present in the routing table, and in addition in the case of redistribution, if learned by a specific protocol source we're redistribution of.

  The nearby X.X.X.X are created by default is different in that the default route is announced only this specific BGP neighbor and not to all the existing BGP neighbors as with previous approaches. The default route will not present in the BGP RIBS of the router that is configured with the command nearby X.X.X.X are created by default and so it will not usually be announced to all the BGP neighbors. At the same time, this command is similar to the default information are created in that the default route is generated artificially and didn't need to be present in the routing table.

  Lingam, let me correct a small inaccuracy: you wrote:

  The "network 0.0.0.0" command enables the router to advertise the default route because the router thinks that 0.0.0.0 is directly connected via Null0.

  In regards to the PMO, the network command does not seek for networks connected directly (as opposed to IGP protocols) but for the networks present in the routing table. They do not need to be directly connected. Properly, the statement should say:

  The command 'network 0.0.0.0' active router advertise the default route because the router has the 0.0.0.0/0 road shows in its routing table.

  Best regards

  Peter

• Complex BGP routing situation

  I have a site where I put a pair of routers, switches behind them linked together, and he made my head. One of the routers has a T1, and have all two LTE modems for backup. I want all the routes that have been advertised on the T1 as primary, but if it fails each router must advertise its own routes on the LTE and be back on the roads of the other router. So what I have to do advertising is something like this:

  R1

  T1-neighbor

  All the normal channels

  LTE-neighbor

  Added after R1 routes

  Prefixes twice R2 routes

  R2

  LTE-neighbor

  Added when R2 routes

  Prefixes twice R1 routes

  So, how I would write config to treat this? And how about what networks BGP on each router must look at when to advertise? Is it still possible?

  All leaving the roads of R2 will LTE all the time is not desirable, because the latency is a problem with the cameras on the site. Finally, R2 will get a T1 and the link between the networks is deleted, but that will probably be the month.

  Adding to my previous comment. This is only an example based on what I see in your post.

  R1

  IP-list of prefixes R1 - ip seq 5 permit 217.217.1.0/24
  IP-list of prefixes R2 - ip seq 5 permit 218.218.1.0/24

  allowed my-ip-to-LTE route map 10
  match ip-list of prefixes R1 - ip address
  defined as the path to precede 500

  allowed my-ip-to-LTE route map 20
  address for correspondence ip-R2 - ip prefix list
  defined as the path to precede 500 500

  out of my-ip-to-LTE-route neighbor 200.200.200.1

  allowed my-ip-to-T1 route map 10
  match ip-list of prefixes R1 - ip address
  address for correspondence ip-R2 - ip prefix list

  out of my-ip-to-T1-route neighbor 100.100.100.1

  on R2

  IP-list of prefixes R1 - ip seq 5 permit 217.217.1.0/24
  IP-list of prefixes R2 - ip seq 5 permit 218.218.1.0/24

  allowed my-ip-to-LTE route map 10
  address for correspondence ip-R2 - ip prefix list
  defined as the path to precede 500

  allowed my-ip-to-LTE route map 20
  match ip-list of prefixes R1 - ip address
  defined as the path to precede 500 500

  out of my-ip-to-LTE neighbor XXX1-route map

  It will be useful,

  Masoud

• Exclude the network using BGP network command

  Hello:

  I am using BGP and I do redistribution of OSPF into BGP while I read the best way to do it is to use the network command.

  Now, I do the redistribution of OSPF in BGP using a list of prefixes that specifies the network to redistribute.

  Is possible to do so by the order of network?

  My network to redistribute is the 8.0.0.0 / 8 but the 8.0.0.0 / 16 is excluded.

  The IGP network is with specific directions of IP, so I think I also use the Auto-resume option or set the order of the aggregate-address.

  Another option that I prefer is to advertise the network into parts because some routers of entry to ACE are better for the first part of the network and the other are better in the second part. So I intend to announce that this networks.

  • 8.0.0.0 / 9 (excluding 8.0.0.0 / 16)
  • 8.128.0.0 / 9

  Thank you very much for your help. In this case, Juan.

  Hi you

  By default, network control announce only mask what u applied and it should be existed in the routing table.

  Another option, you can use the roadmap as well with the network command

  Respect,

  Kazim

  "Please miss me so useful post.