From: Victor Cappuccio (victor@ccbootcamp.com)
Date: Sun Mar 11 2007 - 07:46:31 ART
Hi,
Also For the CEF Load Balancing Part,
http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_command_refer
ence_chapter09186a00800881f8.html
when we have the capability to send traffic over multiple paths to reach a
destination, the router creates a 16-row hash table, The hash that is used in
the CAM can be examined using the show ip cef prefix internal command.
something like
R1#show ip route ospf
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 1.2.12.2, 00:02:16, FastEthernet0/1
[110/2] via 1.1.12.2, 00:02:16, FastEthernet0/0
R1#show ip route 2.2.2.2
Routing entry for 2.2.2.2/32
Known via "ospf 1", distance 110, metric 2, type intra area
Last update from 1.1.12.2 on FastEthernet0/0, 00:02:46 ago
Routing Descriptor Blocks:
* 1.2.12.2, from 2.2.2.2, 00:02:46 ago, via FastEthernet0/1
Route metric is 2, traffic share count is 1
1.1.12.2, from 2.2.2.2, 00:02:46 ago, via FastEthernet0/0
Route metric is 2, traffic share count is 1
R1#show ip cef 2.2.2.2 internal
2.2.2.2/32, version 15, epoch 0, per-destination sharing
0 packets, 0 bytes
via 1.2.12.2, FastEthernet0/1, 0 dependencies
traffic share 1
next hop 1.2.12.2, FastEthernet0/1
valid adjacency
via 1.1.12.2, FastEthernet0/0, 0 dependencies
traffic share 1
next hop 1.1.12.2, FastEthernet0/0
valid adjacency
0 packets, 0 bytes switched through the prefix
tmstats: external 0 packets, 0 bytes
internal 0 packets, 0 bytes
Load distribution: 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 (refcount 1)
Hash OK Interface Address Packets
1 Y FastEthernet0/1 1.2.12.2 0
2 Y FastEthernet0/0 1.1.12.2 0
3 Y FastEthernet0/1 1.2.12.2 0
4 Y FastEthernet0/0 1.1.12.2 0
5 Y FastEthernet0/1 1.2.12.2 0
6 Y FastEthernet0/0 1.1.12.2 0
7 Y FastEthernet0/1 1.2.12.2 0
8 Y FastEthernet0/0 1.1.12.2 0
9 Y FastEthernet0/1 1.2.12.2 0
10 Y FastEthernet0/0 1.1.12.2 0
11 Y FastEthernet0/1 1.2.12.2 0
12 Y FastEthernet0/0 1.1.12.2 0
13 Y FastEthernet0/1 1.2.12.2 0
14 Y FastEthernet0/0 1.1.12.2 0
15 Y FastEthernet0/1 1.2.12.2 0
16 Y FastEthernet0/0 1.1.12.2 0
refcount 6
The load balancing ratio is approximated by number of entries in the hash
table belonging to each path.
for the etherchannel load balancing I find this link very useful
http://www.cisco.com/warp/public/473/4.html
so when multiple physical links exist between 2 switches, these links can be
bundled into a single logical link, so EtherChannel does not do a
frame-by-frame forwarding in a Round Robin.
The load balancing operation performs a X-OR calculation on the 2 lowest bits
of the source and destination mac
A EtherChannel can be configure to be a L2 or L3 Bundle of Ports that are
treated as 1 Logical interface (named Port Channel, I call them Links Glue).
so as Frog mentioned, you have L2 and L3 operations, and CEF will operate at
L3, now that CEF works in conjuntion with the FIB and the adjacency table but
to make L3 Switching at Hardware VERY Fast, is another story... Sure other
Device Vendors call this MPLS ;) naa just kidding...
thanks,
Victor Cappuccio.-
Network Learning Inc - A Cisco Sponsored Organization (SO) YES! We take
Cisco Learning credits!
victor@ccbootcamp.com
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-----Original Message-----
From: nobody@groupstudy.com on behalf of Radioactive Frog
Sent: Sun 3/11/2007 2:07
To: Muhabat
Cc: ccielab@groupstudy.com
Subject: Re: relation in IP CEF and Port-channel
Hi Huhabat,
AFAIK, Port-Channel is based on LCAP and is LAYER 2. On the other hand IP
CEF is layer 3 (IP) based.
I don't think there is any relation between these two load-balancing
algorithm.
Anyone else can expand this debate?
HTH,
Frog.
On 3/11/07, Muhabat <muhabat@gmail.com> wrote:
>
> Hi GS,
>
>
>
> Please can some one help to understand relation b/w IP CEF LOAD-SHARING
> and
> PORT-CHANNEL LOAD-BALANCE.
>
>
>
> Any kind of help will be appreciated.
>
>
>
>
>
> Thanks in advance.
>
>
>
>
>
> Best Regards,
>
> _______________________________________________________________________
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