Questions tagged [bgp]

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

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Same /24 IP prefix, same AS for 2 different locations, possible?

Let's say I have 2 locations: 1. the United States Datacenter 2. the Russian Federation Datacenter I have 1 /24 Subnet with 1 AS. Both sites have a different ISP. My target is to: allocate /24 for ...
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FRR: AIGP or similar round-trip-based route selection for BGP [closed]

Given the configuration: A <-> C A <-> B <-> C A <-> D <-> C Assume the link from A to C is extremely unreliable for some reason, such as a faulty cable. Or, it is ...
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209 views

BGP and NAT Not working

I have an odd issue with BGP+NAT. I have 2 separate routers and 2 different ISP's. Topology looks like this: ISP1--BGP--> RTR1 \ \--OSPF-- Palo Alto Firewall-- Internal ...
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47 views

BGP local-as command clarification

On my network infrastructure, an Arista switch is the core switch and a pfsense server the gateway. BGP is used to advertise routes for all the internal networks. On Arista switch, I see the BGP ...
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59 views

How does the BGP UPDATE message propagation work?

I am currently reading about Routing around Congestion Defense and the non feasibility of this approach. Since to use this method a lot of BGP poisoning would be necessary and to switch paths several ...
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50 views

Route advertisement and FIB programming

Que1. Assuming bgp is running on a network device, will the route advertisement and FIB programming(basically populating entries in hardware) occur in parallel? Or does it occur sequentially, meaning, ...
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High Throughput on BGP Multihomed Network

I've One site connected to my server location via BGP over MPLS and at my server location 2 edge routers cater these WAN links, and are further connected to Servers via switches. Now, Is it possible ...
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99 views

What is the difference between connect and active states of BGP?

What is the significance of having two different states in FSM when both try to establish TCP Connection?
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What does a transition from static IP to BGP look like?

We initially got a /30 from our upstream and now we're ready to start running BGP to advertise our own /24. What does that sort of process typically look like? Does it likely require some prior ...
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142 views

How does aggregate routes behave in BGP?

If a router received two BGP updates for the same prefix and both these updates are aggregate paths how do the router decide which one to take? Let us say that it needs to decide based on AS Path ...
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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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144 views

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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60 views

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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995 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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66 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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35 views

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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196 views

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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25 views

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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49 views

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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26 views

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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32 views

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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956 views

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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69 views

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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1answer
80 views

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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142 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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79 views

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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863 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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109 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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125 views

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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256 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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152 views

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
42 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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172 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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102 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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377 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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1answer
309 views

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: