RANCID and the Octothorpe
RANCID (Really Awesome New Cisco confIg Differ) is a tool for automating the collection of hardware and configuration data from network devices. I recently upgraded an installation from version 2.3.1 to 2.3.8. And naturally, because I didn't have a ton of time to devote to this, stuff broke. It stopped pulling data from some switches. Not all switches, mind, that would be too easy to troubleshoot. Only some.
Zero Trust Networks
I find it interesting that someone is finally putting together a concept that I have been leveraging (where technology allowed me) for some time. Click the link below to find out more.Nexus Accounting Log
Perhaps another trivial post, but if you don’t know about it, you might find it extremely useful. Cisco NX-OS has an on-device log file of the exec level configuration commands entered successfully. Obviously similar informational can be obtained from the TACACS logs, but there is a certain benefit in having directly on CLI. The command […]
Static Routes to an Interface, Not A Next-Hop
Static routes can be handy in some situations where you want to do some quick and (sometimes) easy routing to get the job done, whether replacing the job that a routing protocol would perform, or redistributing the static route into that protocol. The best way to do this would be to identify the remote subnet being routed to, and specify a next-hop IP address to send traffic to so that it can be reached.Static Routes to an Interface, Not A Next-Hop
Static routes can be handy in some situations where you want to do some quick and (sometimes) easy routing to get the job done, whether replacing the job that a routing protocol would perform, or redistributing the static route into that protocol. The best way to do this would be to identify the remote subnet being routed to, and specify a next-hop IP address to send traffic to so that it can be reached.Fast Restoration on IP – MPLS Fast ReRoute
Service providers that have a lot of real-time traffic through their network, like mobile network operators (MNOs), are very keen on a fast restoration of service once a failure occurs in the network. In the past a lot of networks were based on SDH/SONET transport networks, which took care of sub-second (50ms) failovers. Nowadays Ethernet is THE standard for any transport within a service provider network. This introduces an issue, as Ethernet is not built for automatic failover when certain things fail.
Now there are many ways to solve this and I want to dig deeper in these technologies in several posts. I will discuss various protocols that can solve the fast restoration requirement in different ways. Some are used in local situations (so failover to local neighbor, like a twin sibling) and others can be used in inter-site locations or can be an end-to-end protection for certain traffic.
The posts are broken down as follows:
- MPLS Fast ReRoute (this post)
- IP Loop Free Alternate
- BGP PIC Core/Edge
- Hierarchical Forwarding
Please be aware that these technologies are all related to fast restore the layer 3 forwarding path, therefore restoring the MPLS forwarding path. The MPLS forwarding path may be Continue reading
LLDP / 802.1AB-2009 blows
If you're designing L2 discovery protocol, I suppose one of your mandatory requirements is, that you can 'machine walk' the network, after you find one box. I.e. you are able to know your neighbor devices and their ports. LLDP makes no such guarantees
You have 4 mandatory TLVs, [0123], End of LLDPDU, Chassis ID, Port ID and TTL. Chassis ID has 7 subtypes which implementation is free to choose, EntPhysicalAlias (two distinct cases), IfAlias, MAC address, networkAddress, ifName or locally assigned. Port ID also has 7 subtypes which implementation is free to choose, ifAlias, entPhysicalAlias, MAC address, networkAddress, ifName, agent circuit ID, locally assigned.
Now you can send what ever trash via locally assigned and be fully compliant implementation. It seems that it would be wise to mandate sending management address (networkAddress) in ChassisID and SNMP ifindex in PortID (and any _additional_ ones you may want to send, i.e. more than 1, which is not allowed). This way you'd immediately know what OID to query and from which node. Obviously this makes assumption that we have IP address always and SNMP implementation always. If we absolutely must support some corner cases where this is not true, we should Continue reading
JNCIE-ENT lab set-up
As I’m preparing for the various exams (up to the Expert lab) of the Enterprise Routing & Switching track of Juniper I needed a lab to support this. In this blogpost I would like to explain my choice of hardware and software and how I’m going to use this set-up to prepare for the written exams and the lab exam.
Hardware and Software
Based on the blueprint, available on the Juniper website (http://www.juniper.net/us/en/training/certification/resources_jncieent.html), I needed to select hardware and software. The current software version used in the lab is JUNOS 10.4. On the various communities I heard that they want to upgrade this to a JUNOS 11.x (probably 11.4, which is a long-term-support version) software track somewhere this year, but until that time I chose the latest version of 10.4. At time of this writing this is JUNOS 10.4R9.
On the official blueprint there is no real indication of which hardware is used on the lab exam, but when you find your ways through the community sites and with the help from some community friends (special thanks to Chris ;-) I decided to use the SRX100H as router and EX4200 Continue reading
OAM LFM: Part 2 – Junos implementation
This post covers: - OAM implementation on Junos - Default value of OAM LFM parameter (in relation with the Part 1) - Configuration / understanding: Neighbor discovery phase - Configuration / understanding: Remote loopback operation - Configuration / understanding:...OAM LFM: Part 2 – Junos implementation
This post covers: - OAM implementation on Junos - Default value of OAM LFM parameter (in relation with the Part 1) - Configuration / understanding: Neighbor discovery phase - Configuration / understanding: Remote loopback operation - Configuration / understanding:...Nexus load intervals
This is a interesting but a trivial post. Everybody know about the interface command “load-interval” that changes the time period over which the interface packet-rate and throughput statistics are averaged. I discovered an addition to this command on the Nexus the other day while poking around. NX-OS allows multiple counter intervals to be configured on […]
OAM LFM: Part 1 – The theory
1/ Some terms, before: OAM for Operations Administration and Maintenance LFM for Link Fault Management EFM for Ethernet in the First Mile 2/ Introduction: OAM is intended for point-to-point or emulated p2p Ethernet links. The OAM block is optional, so...OAM LFM: Part 1 – The theory
1/ Some terms, before: OAM for Operations Administration and Maintenance LFM for Link Fault Management EFM for Ethernet in the First Mile 2/ Introduction: OAM is intended for point-to-point or emulated p2p Ethernet links. The OAM block is optional, so...
Logging – Levels
There are 8 different logging levels. Enabling higher level messages enables all lower level messages. EX: enabling Debugging level 7 enables all messages.
Level Level Name Description Syslog Definition
0 Emergencies The system is unusable LOG_EMERG
1 Alerts Immediate action is needed LOG_ALERT
2 Critical Critical condition LOG_CRIT
3 Errors Error condition LOG_ERR
4 Warnings Warning Condition LOG_WARNING
5 Continue reading
Stream Ciphers Examples
Here is a list of some of the more common Stream Ciphers
SEAL (Software Encryption Algorithm)
RC4
DES and 3DES leveraging OFB (Output Feedback) or CFB (Cipher Feedback)
Block Ciphers Examples
Here is a list of some of the more common Block Ciphers
Blowfish
RSA
DES and 3DES leveraging ECB (Electronic Code Block) or CBC (Cipher Block Chaining)
AES
IDEA
Skipjack
SAFER (Secure and Fast Encryption Routine)
Cisco Nexus 7000 upgrade to 8Gb
When upgrading a Nexus 7000 to NX-OS version 5.2 (using more than 1 VDC) or to NX-OS v6+, Cisco claims the need to upgrade the system memory to 8Gb. Note I have run on v5.2 using only 4Gb per SUP using 2 VDCs and it has worked just fine, but I should mention that the […]
Symmetric and Asymmetric Algorithms – Basic Differences
Symmetric uses only one key for both encryption and decryption. Sender and receiver share the same shared secret to transfer data securely. Algorithms include DES, 3DES, AES, IDEA, RC2/4/5/6, and Blowfish. Also referred to as "secret key" encryption.
DES - 56bit keys
3DES - 112bit and 168bit keys
AES - 128bit, 192bit, and 256bit keys
IDEA (International Data Encryption Alogrithm) - 128bit keys
RC2 - 40bit and 64bit keys
RC4 - 1bit to 256bit keys
RC5 - 0bit to 2040bit keys
RC6 - 128bit, 192bit, and 256bit keys
Blowfish - 32bit to 448bit keys
Asymmetric uses one key for encryption and another key for decryption referred to as public key infrastructure encryption. Key lengths generally ranging from 512 to 4096bits.
Example of asymmetric encryption RSA,EIGamal, Eliptical Curves, and Diffie Hellman