Questions tagged [bgp]

BGP is Border Gateway Protocol, used on the internet both inside of and in between networks.

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66 views

How BGP guarantees same route for a forwarded packet?

In BGP all routers choose the best route to a single destination. So for Router A and destination D, A will forward the packet to the next-hop router (let us say router R) after knowing the best route ...
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Troubleshooting connectivity in BGP/Quagga/Docker lab

I have created a virtual networking lab to test BGP routing. The lab is made up of two Debian Docker images which serve as end users and two images running Alpine Linux with Quagga to serve as the ...
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Ho to implement RPKI for our Network

I would want to implement RPKI in my network. I have gone through some documents by which i cant understand the implementation process. What are the steps i should follow to implement RPKI in my ...
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How to bypass when network speed over a special number in Juniper?

I have a requirement, such as I have 113.100.15.0/24 segment IP addresses. in Juniper M480 Router I connected to BGP-A(1G) and BGP-B(10G), by default the 113.100.15.0/24 out the Router it go ...
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Is next-hop-unchanged viable for iBGP connections?

Lets look at following drawing: F6, S1 and R1 are in the same network. F6 and R1 are physically connected to switch S1. There is a eBGP neighborship between F6 and R1, and a iBGP neigborship between ...
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968 views

Why do IXPs need ASN?

Does anybody know why an IXP needs to have an ASN? Will that ASN appear in the AS-PATHs or will it be transparent?
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Method to rename the existing BGP peer group

In Cisco ASR router, do we have any method to rename the existing peer group without removing and recreating it?
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Is it possible to change the Local Preference of a route based on the BGP Community of another route?

Lets assume a topology like the following: |-- R2 -> prefix_1 R1 ---| |-- R3 -> prefix_2 If R2 sets a BGP community for prefix_1, is it possible to trigger a Local Preference ...
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53 views

Reasons for buying ASN for organisation that are located at single place

I see here that even some organisation/universities have bought ASN which are located at single location. What benefit they will get by buying ASN ? Is it compulsory to buy ASN if I have to buy some ...
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What is benefit of allocating ASN to edge routers and not Ip addresses

What is benefit of allocating ASN to edge routers and not Ip addresses ? I mean we could have given these edge routers unique public ip addresses too ?
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Global BGP Routing only by only importing supernet prefixes

I was wondering if global IPv4 Routing can be technically achieved only by importing from the ISP Provider (providing us with a IPv4 BGP full table) a subset from the BGPv4 routes (i.e. all prefixes ...
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Packet Clearing House RIB Dumps

I want to use PCH collectors RIB Dumps as another source of information for a project, while I already use Routeviews and RIPE ris. I want to collect the RIBs that are created at 08:00 UTC. This is ...
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In case if BGP connected to two peers then how Graceful restart capability advertised in open message

As per RFC 4724 "A BGP speaker MUST NOT include more than one instance of the Graceful Restart Capability in the capability advertisement [BGP-CAP]. If more than one instance of the Graceful ...
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can some one explain BGP router graceful restart flow?

can some one please explain BGP router graceful restart flow , how the messages will exchange before restart and after session re-establish between BGP router and it's peer.
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Understanding MP-BGP IPv4 AFI

I was writing my own BGP speaker, and I am a bit confused by the IPv4 AFI of MP-BGP. I understand that to exchange IPv6 routing information peers need to agree on it by sending the MP-BGP capability ...
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Why is bgp used for AWS and gcp VPNs and not another routing protocol? [closed]

I use AWS and gcp. Both of these cloud platforms have the ability to establish a VPN connection from a VPC in the cloud to an on-premise router or another cloud VPN endpoint. They both use bgp ( and ...
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bgp filtering based on conjunction of prefix-list and as-path originator

Is there any way of having a filter that uses as-path origin and prefix-list together. For example I want to accept updates from origin of AS 5745 and prefix-list is say 189.150.20.X/24. Any other ...
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What is the use of route-target without export/import?

On my router, I can configure the following: I canont find any information regarding the use of the "route-target ASN:nn" command. I know what route-target import/export allows me to do, but what use ...
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Regarding Administrative Distance

Different vendors use different Administrative distance for the same protocol.For example, in a Cisco router, the eBGP, AD value is 20, whereas in Arista routers, it appears different(i believe, 200). ...
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Does anycast addressing add additional latency in any way?

Does anycast addressing, in itself, add any additional latency to network connections? Specifically, if you had two servers located in the same data center that had extremely similar routes/number of ...
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1answer
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BGP | Advertise a summary prefix out to customer location

I don't know what I should be using for this or how I should go about it. In my lab where I am testing out the BGP configs that I've learned I want my ISP topology to have a summary prefix for the ...
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Route Reflector not reflecting BGP-LU (Labelled Unicast) prefixes

I was reading about the Inter-AS MPLS VPN Option C from book ' MPLS in the SDN Era' . In it , the author establishes the BGP-LU peering between PEs and ASBRs and between RR and ASBR only.No BGP-LU ...
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Whether the anycast nodes can not in the same AS, and whether the different AS can pronounce the same IP segment?

The Anycast realize is through annunciate the same IP address in the different node using BGP protocol. you see the Server A and Server B use the BGP annunciate the same IP address 10.0.0.1. There ...
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2answers
119 views

BGP multi-path using loopback

I have above scenario where i have multiple PATH for my BGP so i have to setup loopback interface to make it ECMP routing on both path. I have cisco nexus switches and following is my first router ...
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How does IP assignment work for servers and data centers

If I had an IP address (for example bought range for my company), and 2 ISPs fibres, how would it be possible to set my network card to have same IP adress accessible from both connections? (know its ...
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847 views

BGP convergence issue

I have 2 different carriers on my Cisco 2921 router and I have set weight to 350 for my first carrier to force it for my outbound traffic, and I set second carrier weight to 300. I am receiving BGP ...
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103 views

Regarding eBGP Multipath

In one of the blogs, i read: "Unlike most routing protocols, BGP only selects a single best path for each prefix. It doesn’t do ECMP (Equal Cost Multi-Path Routing) by default but it is possible to ...
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How to get traffic to take BGP route if not matched in PBR?

I am a newbie to BGP and have an ASR1001x router (172.16.0.3), I'm forwarding an ACL to a second router (172.16.0.1) while I try to get BGP working on this one for a specific testing prefix-list ...
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Hub-Spoke communication with BGP

I'm trying to establish connectivity between Hub and Spoke locations of same enterprise with same AS using BGP. Within DC (hub) iBGP and OSPF is used and eBGP is established between Spokes and MPLS ...
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202 views

No route to host for IPs in same subnet being routed by bgp

I have set up BGP to do some custom routing for a subset of addresses in the range 192.168.1.0/24. I have verified that the BGP is working by testing ping/curl on a different host in a different ...
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Running iBGP without IGP

Given following setup: Configuration of the routers is very straight forward. Router BGP1: interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface Loopback9 ip address 9.9.9.9 255.255....
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VPLS how to signal CE facing interface failure

Hello, I have a BGP-based VPLS setup with one CE machine being multi-homed multi-homing works if i for example shut the active PE or i somehow disturb the connection between my PEs... that ok but ...
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How to force client side HSRP interface to go into standby when internet is not reachable [duplicate]

I have a VIRL setup in which the client router is connected to a client switch that connected to two provider switches that have HSRP configured for the client gateway. The two switches are in an OSPF ...
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1answer
40 views

H-VPLS application with different types of VPLS

so ive been digging around VPLS for a while and i have come across a term H-VPLS. My knowledge is: VPLS can be signalled using LDP (manual or autodiscovery) or BGP (autodiscovery). H-VPLS: ...
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133 views

How to change AD on Juniper router?

I have this route on my Juniper Router and some destinations have two routes: OSPF and BGP. I want to change the administrative distance for the BGP route so that it will be smaller than the OSPF ...
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72 views

How to explain that a route has two different AS numbers?

I have a question about the AS path, see the below example where I show the route 114.114.114.114. This shows several BGP routes. See the fist route item. The AS path is 4809 4134 I, I want to know ...
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1answer
75 views

Can not use `update-source` in bgp neighbor command in Cisco Packet Tracer

In my Cisco Packet Tracer, I have a ISR4321 router: Router1(config-router)#neighbor 12.0.0.2 update-source lo0 ^ % Invalid input detected at '^' marker. I ...
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257 views

What's the meaning of `State` and `PfxRcd`?

When I execute the show ip bgp summary, I get the bellow data: Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 12.0.0.2 4 200 199 190 12 0 ...
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What's the commands of Cisco query bgp neighbor table, bgp table and router table?

In the AS router, I want to query its bgp neighbor table, bgp table, and router table. what's the commands of them?
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Why the last AS PATH item always is `I` or `?`? [duplicate]

you see my snapshot from m Juniper Router, I want to find the routes of 114.114.114.114, but there always get Idle or a ?, why:
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3answers
139 views

Why do all the intermediary routers need to run iBGP without tunneling?

I'm trying to understand the configuration behind iBGP - I understand you can run full mesh to prevent loops, run confederation or route reflectors, if you don't want full mesh, else run tunneling ...
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219 views

What does “Allow AS in” do in BGP?

When configure BGP in a SDN product, i saw there is an option to enable "Allow as in", could anyone know what is it!
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What's the meaning of `%BGP-3-NOTIFICATION: sent to neighbor 12.0.0.1 6/0 (unsupported) 0 bytes `?

In my Router's loopback interface, I configure the following IP address: Router2(config-if)#ip address 2.0.3.2 255.255.255.255 Router2(config-if)# %BGP-3-NOTIFICATION: sent to neighbor 12.0.0.1 6/0 (...
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1answer
51 views

My BGP router does not advertise configured prefixes

I have two Routers, which are Router1(BGP 100) and Router2(BGP 200), they have set up BGP neighbor for each other: this is my Router1's BGP configuration: ! router bgp 100 bgp log-neighbor-changes ...
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Why Cisco BGP neighbor command need the remote-as number?

When I in my Router2 add a neighbor, the bellow is my command: Router2(config-router)#neighbor 12.0.0.1 remote-as 100 you see, I need write two params, one is neighbor address, and the other is its ...
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442 views

Advertise all static route except the default gateway with Juniper SRX firewall

With the following policy, all static routes are advertised via BGP to my neighbor: root@Nitrogen# show policy-options policy-statement bgp-export-policy { term export-statics { from ...
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36 views

Cisco create BGP connection, do we need two direction's neighbor command?

I have two routers like bellow: in the Router1, I configured like bellow: ! router bgp 100 bgp log-neighbor-changes no synchronization neighbor 12.0.0.2 remote-as 200 network 1.0.0.0 mask 255....
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Why can the BGP protocol be implemented across routers, but the OSPF protocol can only be implemented direct connected routers?

Why can the BGP protocol be implemented across routers? But the OSPF protocol can only be implemented on directly connected routers? Is the OSPF protocol based on IP? we know the BGP is based on ...
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1answer
46 views

Juniper router how to check the BGP process port?

Juniper router how to check the BGP process port? If I have a router with IP address 12.12.21.1, we know it run a BGP process, which use TCP 179 port as default. How can I check if port 179 is ...
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211 views

How to understand the output below from BGP?

I don't understand some data of the show route: admin@MX-RE0# run show route 36.250.236.6 inet.0: 736608 destinations, 806660 routes (736608 active, 0 holddown, 7 hidden) + = Active Route, - = Last ...