31 May

BGP Administrative Shutdown Communication

I recently came across an excellent draft at IETF by Job Snijders &  friends.  This is to address scenarios where a network might miss communication about a maintenance activity when BGP shutdown happens. Once implemented, this can potentially offer to send peer a message with up to 128 bytes with info about shutdown like “Ticket XXX: We are upgrading the router, will be back live in 1hr” etc. It depends by appending such data to the sys notification which is part of BGP protocol. This is one which sends a message just before the shutdown of the session. So it similar to the way you see session tearing down due to prefix limits etc. This has already been implemented in some of the open source routing implementations like OpenBGPd, GoBGP, PMacct, Exabgp etc.

 

Here’s the latest draft of this change: https://tools.ietf.org/html/draft-ietf-idr-shutdown-09. And here’s Job’s talk from NANOG conference at the start of this year.

 

Hopefully, we will see this implemented across large vendor routers!

06 Apr

Route filter generation for Mikrotik RouterOS via IRR

A while back I posted about routing filter generation via bgpq3 for Cisco (ios and XR) and Juniper JunOS based routers. I have received a number of emails in last few months about automated filter generation for Mikrotik routeros. Since Mikrotik’s CCRs are getting quite popular across small to mid-sized ISPs.

So this blog post is about ways for generating filter config for a given ASN via IRR. One can use such logic with some kind of remote login mechanism like rancid (look for mtlogin here).

I tried building around bgpq3 but it seems more easy with another popular tool in the domain called IRR Power Tools. Once IRR Power Tools (IRRPT) is setup, it allows us to fetch prefixes based via Internet Routing Registries and also aggregates them.

 

So, for instance, let’s pick AS54456:

anurag@tools:~/irrpt$ bin/irrpt_fetch 54456
Processing AS54456 (Record 1)
   - Importing /home/anurag/irrpt/db/54456                   version 1.1
   - Importing /home/anurag/irrpt/db/54456.4                 version 1.1
   - Importing /home/anurag/irrpt/db/54456.6                 version 1.1
   - Importing /home/anurag/irrpt/db/54456.agg               version 1.1
   - Importing /home/anurag/irrpt/db/54456.4.agg             version 1.1
   - Importing /home/anurag/irrpt/db/54456.6.agg             version 1.1
Completed processing of 1 IRR object(s).
anurag@tools:~/irrpt$

 

So now we have got prefixes and this includes both basic route objects as well as aggregates.

anurag@tools:~/irrpt$ cat /home/anurag/irrpt/db/54456.4
199.116.76.0/24
199.116.77.0/24
199.116.78.0/24
199.116.79.0/24
anurag@tools:~/irrpt$
anurag@tools:~/irrpt$ cat /home/anurag/irrpt/db/54456.4.agg
199.116.76.0/22
anurag@tools:~/irrpt$

 

It offers a nice interface for generation of config for Cisco, Juniper, Extreme, Foundry and Force10. Example:

anurag@tools:~/irrpt/bin$ ./irrpt_pfxgen -f cisco 54456
conf t
no ip prefix-list CUSTOMER:54456
no ipv6 prefix-list CUSTOMERv6:54456
ip prefix-list CUSTOMER:54456 permit 199.116.76.0/22 le 24
end
write mem
anurag@tools:~/irrpt/bin$
anurag@tools:~/irrpt/bin$
anurag@tools:~/irrpt/bin$ ./irrpt_pfxgen -f juniper 54456
policy-options {
    replace: policy-statement CUSTOMER:54456 {
        term prefixes {
            from {
                route-filter 199.116.76.0/22 upto /24;
            }
            then next policy;
        }
        then reject;
    }
}
policy-options {
    replace: policy-statement CUSTOMERv6:54456 {
        term prefixes {
            from {
            }
            then next policy;
        }
        then reject;
    }
}
anurag@tools:~/irrpt/bin$

 

So I put a routeros instance in a VM to test and create config from their CLI. Config looks something like this:

[admin@MikroTik] > routing filter add chain=Cloudaccess prefix=199.116.76.0/22 prefix-length=22-24 action=accept
[admin@MikroTik] > routing filter add chain=Cloudaccess  action=reject
[admin@MikroTik] >

This seems logical and can be scripted. So one can have a script to read the aggregate file and if aggregate says /24 one can put it directly in the filter else allow filter up to /24 from whatever range the pool starts and similar logic in IPv6.

So here’s the script:

#!/bin/bash

# Script for generating BGP filter for Mikrotik RouterOS
# Input name of chain via $1 and ASN via $2

irrpt=/home/anurag/irrpt


# Grab latest filters via RADB / other IRRs using IRRPT
echo "Grabbing prefixes for AS$2"
php $irrpt/bin/irrpt_fetch $2


echo "***Start of Mikrotik routeros config below***"


# IPv4 config part
cat $irrpt/db/$2.4.agg | while read prefix

do
masklength=`echo $prefix|awk -F '/' '{print $2}'`
if [ "$masklength" -eq 24 ]
	then
	# Prefix is a /24 - generating config without defining prefix length
	echo "routing filter add chain=$1-IPv4 prefix=$prefix action=accept"


elif [ "$masklength" -lt 24 ]
	then
	# Prefix is greater than /24 - generating config with prefix length upto /24
	echo "routing filter add chain=$1-IPv4 prefix=$prefix prefix-length=$masklength-24 action=accept"

fi
done
# Last entry for denial of pools
echo "routing filter add chain=$1-IPv4 action=reject"




cat $irrpt/db/$2.6.agg | while read prefix6

do
masklength6=`echo $prefix6|awk -F '/' '{print $2}'`
if [ "$masklength6" -eq 48 ]
	then
	# Prefix is a /48 - generating config without defining prefix length
	echo "routing filter add chain=$1-IPv6 prefix=$prefix6 action=accept"


elif [ "$masklength6" -lt 48 ]
	then
	# Prefix is greater than /48 - generating config with prefix length upto /48
	echo "routing filter add chain=$1-IPv6 prefix=$prefix6 prefix-length=$masklength6-48 action=accept"

fi
done
# Last entry for denial of pools
echo "routing filter add chain=$1-IPv6 action=reject"




echo "***End of Mikrotik routeros config***"

 

So the script works except with a small bug in IPv6 aggregation which is the issue with IRRPT and I have reported same on their GitHub project page here.

 

An example of the script in progress for Cloudaccess AS54456:

anurag@tools:~/irrpt$ ./routeros.sh Cloudaccess 54456
Grabbing prefixes for AS54456
Processing AS54456 (Record 1)
Completed processing of 1 IRR object(s).
***Start of Mikrotik routeros config below***
routing filter add chain=Cloudaccess-IPv4 prefix=199.116.76.0/22 prefix-length=22-24 action=accept
routing filter add chain=Cloudaccess-IPv4 action=reject
routing filter add chain=Cloudaccess-IPv6 action=reject
***End of Mikrotik routeros config***
anurag@tools:~/irrpt$

 

Here’s another example of it in action with NPCI’s AS132351

anurag@tools:~/irrpt$ ./routeros.sh NPCI 132351
Grabbing prefixes for AS132351
Processing AS132351 (Record 1)
   - Importing /home/anurag/irrpt/db/132351                  version 1.1
   - Importing /home/anurag/irrpt/db/132351.4                version 1.1
   - Importing /home/anurag/irrpt/db/132351.6                version 1.1
   - Importing /home/anurag/irrpt/db/132351.agg              version 1.1
   - Importing /home/anurag/irrpt/db/132351.4.agg            version 1.1
   - Importing /home/anurag/irrpt/db/132351.6.agg            version 1.1
Completed processing of 1 IRR object(s).
***Start of Mikrotik routeros config below***
routing filter add chain=NPCI-IPv4 prefix=103.14.160.0/22 prefix-length=22-24 action=accept
routing filter add chain=NPCI-IPv4 action=reject
routing filter add chain=NPCI-IPv6 prefix=2001:df0:2f0::/46 prefix-length=46-48 action=accept
routing filter add chain=NPCI-IPv6 action=reject
***End of Mikrotik routeros config***
anurag@tools:~/irrpt$

 

 

 

 

Thinking to automate? 

The config between ***start*** and ***end*** can be pasted directly in CLI with Mikrotik. I would not recommend using it for manual filtering of any larger network. Automated filtering where filters are generated regularly makes sense but manual filtering without automation can be damaging. One can use a script like this for connecting to smaller networks. Also, IRRPR offers diff management via CVS (I hope they come up with git on that part) and it comes with an option to trigger email update so Network admins can know when to manually update. I would prefer that for non-commit based platforms since with Cisco ios or Mikrotik routeros it can be tricky to auto update prefix list. If one does no ip prefix list before triggering update it will cause a major noticeable impact. So ideal way to manage that on non-commit based devices would be to maintain a list of prefixes separately in the plain text file or a database and diff it against old one & only push for changes. Do-able and should be preferred that way instead of deleting and re-adding the whole list while automating.

 

Time to get back to work! 🙂

25 Nov

Peering with content networks in India

peering

One of frequent email and contact form message I get my blog is about available content networks in India and where one can peer. There are certain content networks in India and of course most of the content networks have open peering policy and are usually happy with direct inter-connection (we call as “peering“) with the ISP networks (often referred to as “eyeball networks”). Some of these networks have a backbone which connects back to their key datacenter locations on their own circuits via Singapore/Europe, some other have simply placed their caching server where cache fill happens over IP transit.

 

Based on publically known information across community and of course peeringdb, following content players are available in India and known to be open for peering:

  1. Google
  2. Microsoft
  3. Amazon
  4. Limelight

 

A quick list of these with datacenter names and locations as taken from Peeringdb record of these networks.

Organisation ASN City Datacenter Location
Amazon 16509 Mumbai GPX Mumbai Unit A-001, Boomerang Chandivali Farm Road, Near Chandivali Studio, Andheri East Mumbai, Mumbai, 400 051
Amazon 16509 Noida Sify Greenfort – Noida B7, Block A, Sector 132, Noida Expressway, Noida , UP 201304
Amazon 16509 Mumbai Tata Mumbai IDC LVSB, Opposite Kirti College
6th floor, Prabahdevi
Mumbai, MH, 400 028
Google 15169 Chennai Bharti Airtel Santhome Bharti Towers, 101 Santhome High Road, Chennai, 600 028
Google 15169 Mumbai GPX Mumbai Unit A-001, Boomerang Chandivali Farm Road, Near Chandivali Studio, Andheri East Mumbai, Mumbai, 400 051
Google 15169 Noida Sify Greenfort – Noida B7, Block A, Sector 132, Noida Expressway, Noida , UP 201304
Google 15169 Chennai TATA Communications Ltd 14th floor, 2nd block
4, Swami Sivanand Salai, Chennai, TN 600 002
Google 15169 Delhi Tata Delhi VSB, Bangla Sahib Road, New Delhi 110001
Google 15169 Mumbai Tata Mumbai IDC LVSB, Opposite Kirti College
6th floor, Prabhadevi
Mumbai, MH, 400 028
Limelight 55439 / 22822 Chennai Bharti Airtel Santhome Bharti Towers, 101 Santhome High Road, Chennai, 600 028
Limelight 55439 / 22822 Mumbai Netmagic Vikhroli Mehra Industrial Estate
LBS Marg, Vikhroli
Mumbai, 400 079
Microsoft 8075 Mumbai Bharti Airtel Mumbai Plot No, TPS-2, 14/3, 2nd floor
Dattatray Road, Linking Road Extension
Mumbai, 400054
Microsoft 8075 Chennai Bharti Airtel Santhome Bharti Towers, 101 Santhome High Road, Chennai, 600 028
Microsoft 8075 Chennai TATA Communications Ltd 14th floor, 2nd block
4, Swami Sivanand Salai, Chennai, TN 600 002
Microsoft 8075 Delhi Tata Communications Ltd – GK1 Greater Kailash-1
New Delhi, 110048
Microsoft 8075 Mumbai Tata Mumbai IDC LVSB, Opposite Kirti College
6th floor, Prabhadevi
Mumbai, MH, 400 028

 

Besides these Google also has an option of GGC, Akamai has an option of Akamai Caching server, Facebook has the option for caching server which is hosted inside ISP’s network and Netflix has an option for OCAs. Besides these networks there are known nodes of Verizon’s Edgecast in Delhi, Mumbai & Chennai (as per this map), Cloudflare has nodes in Delhi, Mumbai & Chennai (as per this map), PCH & K-root server have a node with Web Werks available on MCH peering fabric and Dyn has a node in Mumbai (as per this map).

Go ahead and peer as after all it all starts with a handshake. 🙂