Questions tagged [bgp]

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

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9 votes
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BGP remote-triggered blackhole (RTBH) filter for Juniper

I'm trying to find the most elegant way to implement a RTBH filter for routes received from a customer. The filter should: Only accept the customers own prefixes from a prefix-list Only accept /32 ...
Sebastian Wiesinger's user avatar
9 votes
2 answers
527 views

How to handle performance degradation deep in your provider's network?

What are some possible ways to detect packet loss deep in a provider's network that is several hops away? With multiple providers peered over BGP on our Internet edge routers, I need to be able to ...
generalnetworkerror's user avatar
10 votes
3 answers
4k views

Inbound BGP load-balancing from same ISP router

I have two BGP routers for DIA with an issue with one provider in that the two links to this provider land on the same SP router. My ethernet handoffs via two separate MetroE links from another ...
generalnetworkerror's user avatar
10 votes
2 answers
6k views

load balance between two ISP bgp links

I have up-links to two separate ISPs on one router and receive a default route from each via BGP. Both links are the same speed and BGP is used only to advertise our prefixes out. Whats the best way ...
phesen's user avatar
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5 votes
1 answer
7k views

BGP expanded community-list regex

I need to verify that the following regex will match against my criteria, which is: Deny any prefixes beginning with 0: Deny any prefixes beginning with 65000: Deny any prefixes beginning with 0:...
John Jensen's user avatar
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11 votes
1 answer
838 views

How can I check to see if I am receiving MED's?

I have a BGP session with a transit provider in two different cities. We are both using the same AS at both locations. I am expecting them to be sending me MED's for me to use for routing decisions ...
zevlag's user avatar
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10 votes
4 answers
3k views

Embedded routers vs. software routers in the datacentre

I've been looking for a new 'core' router to put in our new rack which is colo'd at a nearby datacentre. What I've come across is the usual Cisco/Juniper/Brocade lineup, with the usual unattractive ...
Libbux's user avatar
  • 515
17 votes
3 answers
910 views

Is it possible to remotely influence BGP localpref?

A colleague is attempting to implement active/passive internet multihoming. The design entails sending communities (listed below) to the passive provider to lower the local preference at remote ASes ...
Dennis Olvany's user avatar
11 votes
3 answers
857 views

Circular BGP propagation

This one is a difficult to describe, it's hypothetical because I'm learning about routing and right now I'm focused on BGP. Let's say my ASN is 65000, and I announce 192.0.2.0/24. My peer, AS 65001 ...
Libbux's user avatar
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15 votes
3 answers
3k views

Why does BGP RR only reflect the best path?

Can anyone answer why does BGP RR only reflect the best path?
Bo Cao's user avatar
  • 401
0 votes
2 answers
6k views

Advantages to BGP peering over VPN

Given the advantages to be gained by creating a BGP session with a remote AS over a VPN connection (such as traffic ingress and egress control) why are there no providers offering this type of service?...
Michael McConnell's user avatar
29 votes
1 answer
11k views

Route servers and looking glasses - what are they?

I've heard the term "route server" and "looking glass" thrown around here. What are they, and why should I care?
John Jensen's user avatar
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6 votes
2 answers
4k views

Telefonica Looking Glass?

Is there an openly accessible Looking Glass for Telefonica ? None of the "official" URL's listed hereunder point to a functional Looking Glass server http://www.telefonica-wholesale.com/es/herraIP....
user887's user avatar
  • 61
19 votes
4 answers
7k views

Routing traffic out different links from the same BGP AS

I have two sites, A and B, in BGP AS 65000, and a third site, C, in AS 65001. All three sites have connectivity via carrier MPLS and there is internal connectivity between sites A and B. I am trying ...
Jeremy Stretch's user avatar
11 votes
2 answers
812 views

BGP Prefix Announcement Issue

I'm having a weird issue. Here is the setup. We have 2 Foundry SX's. SX01 ---> ISPA | | SX02 ---> ISPB I have a /24 from ISPA and another /24 from ISPB. Both /24's are able to be ...
Network Samurai's user avatar
8 votes
3 answers
6k views

BGP - Soft Reset Outbound & Verification

My understanding of the command: clear ip bgp * soft out is that the router on which the command is issued will re-advertise everything it knows about BGP to it's neighbors. As I see it, it's as if ...
BrianK's user avatar
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5 votes
3 answers
692 views

address-family ipv6 on Cisco 3560G

Is anyone aware of an IOS version for the C3560G that supports configuring a neighbor to exchange IPv6 routes? Apparently 12.2(37)SE Advanced IP Services can't do it - as soon as you try to activate ...
Olipro's user avatar
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10 votes
2 answers
2k views

Why does my Cisco 6509 BGP table use two entries in my TCAM?

I have a problem on my Cisco 6509, each entry in my BGP table occupies two entries in the TCAM. If I show capacity forwarding, I see MPLS entries in L3 forwarding resources. But, I do not use MPLS on ...
Johann M.'s user avatar
  • 103
13 votes
1 answer
3k views

What is the maximum prefix size routed in the IPv6 Internet?

In v4, most of the operators filter BGP updates for prefixes longer than a /24, to preserve the size of the full view. What about IPv6 ? Is there such "convention" that stands out ?
Benjamin A.'s user avatar
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17 votes
5 answers
3k views

How to choose a BGP router ID when using IPv6 only?

Usually, when using BGP, you can choose (or your device chooses four you) a router ID from one of your assigned public IP addresses. Now, let's admit you only run IPv6. As the router ID is still a 32 ...
Benjamin A.'s user avatar
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15 votes
5 answers
2k views

How to filter non-bogon prefixes received via BGP from an Internet Exchange(IXP)?

When connected to an Internet peering exchange(IXP), what is a good way to make sure that people don't send you prefixes that they shouldn't be announcing? With regards to bogons I'm aware of the ...
SimonJGreen's user avatar
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8 votes
1 answer
2k views

Does RIP to BGP redistribution for an MPLS VPN make sense?

A customer was recently adamant to perform redistribution of their RIPv2 routes into BGP. This is over a standard MPLS VPN solution whereby the CE routers are fully managed. This approach feels ...
MattE's user avatar
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7 votes
2 answers
141 views

RPKI in the Enterprise

What is the concensus on the use case for RPKI? Is it useful for a stub AS to perform route validation or is this better left to the providers?
Dennis Olvany's user avatar
11 votes
7 answers
4k views

Only One Path in the Looking Glass

I understand that only the best path is advertised to eBGP neighbors, but is this true of iBGP? If I peer with two providers, I was under the impression that anyone else peering with both of my ...
Dennis Olvany's user avatar
14 votes
2 answers
953 views

What is the purpose of BGP TTL security?

What attack vectors does the BGP TTL security knob protect against?
Aaron's user avatar
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33 votes
5 answers
3k views

Better Enterprise Multihoming

I would like to get some opinions regarding ways in which I can improve a BGP dual-provider, dual-router design. Each provider supplies a /24 public subnet. I will refer to the routers, circuits, ...
Dennis Olvany's user avatar
21 votes
4 answers
23k views

Troubleshooting "Down BGP" connections

Our network experienced a short outage when one of our BGP routes went down for a short time yesterday. Thankfully our connections failed over to our secondary BGP route after a few minutes, and the ...
John Lee's user avatar
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