Showing posts with label router. Show all posts
Showing posts with label router. Show all posts

Thursday, March 5, 2015

Software Defined Networking (SDN) class at Coursera

Looking forward to this class starting May 25th, 2015:

https://www.coursera.org/course/sdn

Software Defined Networking

About the Course


This course introduces software defined networking, an emerging paradigm in computer networking that allows a logically centralized software program to control the behavior of an entire network. 

Separating a network's control logic from the underlying physical routers and switches that forward traffic allows network operators to write high-level control programs that specify the behavior of an entire network, in contrast to conventional networks, whereby network operators must codify functionality in terms of low-level device configuration. 

Logically centralized network control makes it possible for operators to specify more complex tasks that involve integrating many disjoint network functions (e.g., security, resource control, prioritization) into a single control framework, allowing network operators to create more sophisticated policies, and making network configurations easier to configure, manage, troubleshoot, and debug.

Tuesday, October 4, 2011

F5 LTM GTM IPv6 quick hit

Just quick note, F5 products LTM and GTM work just great with IPv6.  But IPv6 address shortening (double-colons '::') is not permitted in the GUI or tmsh.
LTM and GTM are Linux based systems, so if you are using BASH, the standard rules apply.
But if you are using the GUI or tmsh, IPv6 addresses must be fully completed.
This:
fe80:0:0:0:201:d7ff:fed4:d041
Not this:
fe80::201:d7ff:fed4:d041     ^^  Cannot have a double colon.

Wednesday, September 28, 2011

IPv6 SLAAC(er)

Promoted as a feature of IPv6, allows a device to connect to a network and receive an addresses without the administrative overhead of managing a DHCP.

But there are a few limitations that limit its usefulness in an enterprise environment:

  • SLAAC only works with /64 subnets. No more, no less.
  • SLAAC does not hand out DNS information (or any Windows domain specific info).

You get an address, a fixed subnet, and a default gateway. Period. This doesn't make it entirely useless, but definitely SLAAC is not a DHCP killer.

To enable a Cisco router to being making SLAAC announcements, all you need to do is configure an interface with an IPv6 address and a /64 subnet:

interface GigabitEthernet0/2
no ip address
duplex auto
speed auto
ipv6 address 2001:1890:1208:240::1/64

This line:

ipv6 address 2001:1890:1208:240::1/64

causes the router to begin making ND announcements which permit other devices to SLAAC themselves. We can verify announcements with a show ipv6 interface:


V6-R1-2911#sh ipv6 int gi0/1
GigabitEthernet0/1 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::xxxx:xxxx:xxxx:xxxx
No Virtual link-local address(es):
Global unicast address(es):
   2001:xxxx:xxxx:xxxx::1, subnet is 2001:xxxx:xxxx:xxxx::/58
Joined group address(es):
   FF02::1
   FF02::2
   FF02::1:FF00:1
   FF02::1:FFFD:CCC1
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ICMP unreachables are sent
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds (using 30000)
ND advertised reachable time is 0 (unspecified)
ND advertised retransmit interval is 0 (unspecified)
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
ND advertised default router preference is Medium
Hosts use stateless autoconfig for addresses.
V6-R1-2911#