Questions tagged [bgp]

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

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Why iBGP speaker should not modify next hop address?

I understand the concept of "Split Horizon" that an iBGP router A learns an external route from an iBGP router B, thereafter, iBGP router B will not advertise the same route to other iBGP ...
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7 votes
3 answers
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Can I announce the same block of /24 given to me by ARIN at two different locations?

The setting: Two locations I'm trying to connect. I have a /24 address block from ARIN Both location have the Same ISP. The Question: Can I announce the same /24 address block at the HQ location to ...
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Cisco BGP Configuration

I need to configure a Cisco C1113 (router B) to enable BGP Routing between two networks. I configured my router B, but I would need to make sure that my configuration is correct... Here is the ...
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How do I view BGP communities of received routes in IOS XE before they go through route-map import policy?

I want to see the communities that are attached to a route when I first receive the route before it goes through the BGP import route-map. In my instance the route-map strips communities off so I ...
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BGP Protocol configuration between two VPC

I would need to configure a cross connect between two VPC networks via SFP Fiber. Unfortunately I'm new on BGP configuration and would need confirmation that I'm doing it on the right way... I have ...
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How does BGP router know the L2 address (MAC address) of the clients?

My situation is that I have 10 Linux servers announcing the same VIP (10.0.0.10 for example) to the router with bird, so the router is doing kind of load balancing with ECMP. ...
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Multi-Home BGP on ASA 5500

We have an ASA that has been doing iBGP for hosted networks. These networks include public address spaces that are routed inside our networks. Recently we have changed providers. The new provider does ...
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Does BGP protocol is required to run IS-IS Segment Routing?

In order to do IS-IS segment routing, do I need to run BGP on routers? Lets say, I have R1-R2-R3-R4 topology. In this topology, I will configure IS-IS segment routing on all routers. My question is do ...
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Traceroute and BGP Next-hop [duplicate]

I just started learning about network engineering and have a very basic question. From my understanding, traceroute shows the routers along the path that the packet needs to traverse through to reach ...
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What would happen if BGP identifier field of both the routers are identical

Say we have two routers R1 and R2. R1 has a router id configured as 1.1.1.1 R2 also has the same router id configured i.e. 1.1.1.1 R1 and R2 are connected to each other via a P2P link. This has an ...
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Limitations of Bilateral peering at an IX

Are there any disadvantages to setting up peering with every other (open) ISP at an IX? All I'm sure is that this could make peering cheaper since the reliance on Tier 1 providers decreases.
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Problem with bgp aggregate-address behavior in iOS when a large number of OSPF routes update all at once

We have a direct connect setup to AWS using BGP. We are running a ISR4451 with IOS XE 16.03.06. I have a strange situation where the AWS BGP neighbor drops our connection with the notification: ...
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Summarization on received Routes - BGP

We need to do Summarization on received Routes (as we are receiving 20K+ routes )to reduce load, saving memory, bandwidth, and CPU Cycle. Please suggest some quick and accurate methods to do. I m ...
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2 votes
1 answer
261 views

In practice, how are BGP Advertisement destinations determined and configured?

Say there is ISP-Alice (ISP-A) and ISP-Bob (ISP-B). They both serve neighboring areas, but they currently only peer with ISP-Charlie. They want to change that and peer directly with each other to ...
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How much RAM you actually need to keep whole global BGP routing table?

It seems that different sources claim very different RAM consumption for having whole BGP routing table information in RAM and having the router to correctly route the traffic. According to ...
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How do two clients of a route reflector learn about each other when no IGP/static-route is used?

I recently learnt that Route reflectors are an efficient alternative to full mesh IBGP peering in a large AS. Imagine a network like: D1 - AS1 <e> R_P <i> RR <i> R_Q <e> AS3 - ...
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How a single BGP-process establishes sessions with neighbours in different VRFs?

In VRF-lite solution scenario, when BGP session is established between CE connected to a VRF in PE. The BGP process or in other words TCP server, is listening on port 179(default) for incoming BGP ...
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Can I assign one of my publicly available IP address to my AWS instance?

I would like to be able to use one of my publicly accessible ip addresses directly with my aws cloud instance. Is there a way I can assign or transfer one of my ip address to aws? My ARIN registry ...
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2 votes
5 answers
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BGP <-> OSPF Route Redistribution Loops

In the following topology I have a multi-point redistribution from BGP <-> OSPF and I have recently encountered a routing loop. After further reading I have understood the problematic routers ...
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What is the minimum number of IP addresses an autonomous system can have?

Is it possible to have an autonomous system with just one IP address?
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BMP Server on Cisco [closed]

I'm using router Cisco 2900 series with Cisco IOS 15.4(3) M3, and there is no BMP (BGP Monitoring Protocol) configuration. What should I do? What Cisco IOS version that provide BMP?
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Juniper "show route receive-protocol bgp" output meaning

When you show the received route from a specific neighbor in BGP with a Juniper, the output is the following : show route receive-protocol bgp X.X.X.X inet.0: V destinations, W routes (X active,...
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public ip over private lease line

I have a private cross-connection with a service provider This private connection is connected from my firewall to their router and the L3 IP range /30 for this segment is private However, i just ...
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Valid routes iBGP advertisements

Routers announce to their iBGP peers, the Best routes for each networks it has in its database Is it possible, to announce additionally to the Best route, also all the Valid routes to the iBGP peers ?
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iBGP Question reagrding Distribute - List from EIGRP

So, I have the following topology. A-B | | C-D A-B-C-D are Routers. It doesn't matter what are the IP's of the interfaces. What matters is that I have 2 loopbacks for each router. 1.1.1.1 and 11.11....
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BGP Traffic Engineering - Active\Passive

At my organization we historically would get T1 ISPs at our POPs and take full table + default. BGP would simply "do it's thing" and for the most part everything worked out. There are ...
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Understanding BGP communities

Lets take this basic topology: RTR A ---- RTR B Routers A and B have an eBGP connection. At router B we can have a route map saying: match: community-list xyz action: permit/deny etc Questions: How ...
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How to configure loopback for switch management

We have Cisco Switches (Nexus 93). My PC is on vxlan, in vrf "test" with default gateway 60.254. We want to use loopback 99 for managent for switches. We have created a loopback 99 with an ...
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How to isolate in VRF clients with public IPs in MPLS ISP network

I have OSPF and MPLS enabled in network and run xconnects to transmit L2 traffic. But also have just Internet clients that want public IP addresses. So I configure public IP on interface towards ...
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What determines if a Juniper router is a route reflector client?

When I read bgp router reflector document: You see the topology is this: You see the Router A B C are in one cluster, D E are not clients of it. but how to configure to become this? I compared with ...
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Cisco IOS XR not sending multiple copies of a prefix despite that the additional-path feature is enabled

I have an iBGP session between a Juniper router and a Cisco IOS XR router with add-path/additional-path both in send and receive direction enabled. According to show bgp neighbor, the feature is ...
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BGP route advertised but cannot Ping

I have this rather basic setup with 3 routers running BGP, each has Loopback int configured. Is there an extra step required for R2 to ping R4 Loopback interface despite it's being advertised? R2#sh ...
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3 answers
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BGP-OSPF route injection doesn't work

Background: BGP is fully functional and works as expected so nothing need to worry about, the problem is the route injection between HK_Office <> HK2 and LON1 <> LON_Office, as you could ...
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Why the iBGP's loopback network is not valid in AS?

This is my test topology: this is my Routers' detail configuration: <R1>display current-configuration # sysname R1 # router id 1.1.1.1 # aaa authentication-scheme default authorization-...
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Why the iBGP received network is not valid?

I test the BGP in my PC, this below is the topology: R1--(eBGP)--R2--(iBGP)--R3. and R2-R3-R4 are in OSPF(omit details). this is my detail configuration of BGP: [R1-bgp]dis this # bgp 100 peer 10.1....
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Understanding the BGP Peer point, BGP Peer and BGP peering session

In my test case, there have 3 ASs. the connections is below: I want to use this case to understand the BGP peer , BGP peering point and BGP peering session. in my understanding: BGP peer means the ...
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Peering of ISPs

How does having multiple peers affect an ISPs performance? If I have 2 option of ISPs to select from, where ISP1 has only 2 peers and ISP2 has 10 peers, which one should I select? Or does number of ...
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5 votes
1 answer
146 views

Change BGP Dampening parameters for a specific neighbor

When you configure the BGP Dampening, the configuration is set for all eBGP neighbor in a Cisco router. There is a way to customize the parameters for a specific neighbor ?
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Why the route comes from different AS?

Before, I know the AS path of BGP properties, such as the 200 100i means the route originate from AS100, use network import the route and through AS200, however in my case: admin@MX480> show route ...
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Redirect Junos IP public -> IP private

we have an MX204 here that works as our BGP, border router and it is gateway of a service that has private IP, I need to access this service with private IP outside our network, you can tell me if I ...
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1 answer
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What's the BGP route `active received accepted damped` status meaning?

when I use show bgp summary command in Juniper router: admin@LA-MX-RE0> show bgp summary Groups: 20 Peers: 20 Down peers: 3 Table Tot Paths Act Paths Suppressed History Damp State ...
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3 votes
3 answers
498 views

Multihoming with two 'good' providers - load sharing strategy?

We get two 100G links, one from each provider and our aggregate traffic is sub 100G. The rationale is one provider can fail and the other will pick up the slack with zero degradation. Our traffic ...
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VXLAN working over IGP, but no NVE peers or EVPN routes in BGP

I'm an absolute beginner with NX-OS and VXLAN. I'm trying to set up a very simple configuration for VXLAN/EVPN/BGP. I have one NX-OSv spine and two leaf switches. No VPC, no anycast SVI. The ...
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What are the benefits of using MP-BGP multicast address family, under the context of inter PIM domains multicasting?

Under the context of inter PIM domains multicasting, 1 RP on each PIM domain (2 domains), attached with eBGP, with MSDP peering to exchange the actives sources, what are the benefits of using the MB-...
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1 vote
2 answers
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BGP Cisco best practices to filter client asn and prefixes

I have two bgp routers. OSPF as IGP and on Loopback's iBGP. Both routers have different peers, but both receive full routing table. I have to connect client through BGP and give him full table. Client ...
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BGP Cisco internal and external distance

I have two bgp routers. OSPF as IGP and on Loopback's iBGP. Both routers have different peers, but both receive full routing table. In google I found on many presantations "bgp best practisec&...
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2 votes
1 answer
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Can't send message from RIP to static through BGP

Before deep into the question, please see this topology and the results of sending messages from one router to the other router: I have succeeded in sending a message from R0 to R2 (or vice versa), ...
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6 votes
2 answers
450 views

BGP traffic management

I have a set-up of two AS's, each AS with two routers (BGP turned up with neighbouring between AS) communicating with each other. I also have specific networks inside the AS's in which I want to use a ...
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Getting VRF to work (and some other questions)

I'm messing with BGP/MPLS for the first time and I have some doubts both in if I'm doing something wrong with my configuration and if it is the best approach, hope you guys can clarify me a bit here. ...
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Routing IPs through another ASN

So currently we have a few /24 ranges that we are looking to use on an upcoming project, we also have an ip circuit with a tier-1 ISP and bgp peering is established. Me and my business partner know ...
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