diff --git a/radius/src/core/mod.rs b/radius/src/core/mod.rs
index b137f92..d051329 100644
--- a/radius/src/core/mod.rs
+++ b/radius/src/core/mod.rs
@@ -30,3 +30,4 @@ pub mod rfc6911;
 pub mod rfc7055;
 pub mod rfc7155;
 pub mod tag;
+pub mod vsa;
diff --git a/radius/src/core/rfc2865.rs b/radius/src/core/rfc2865.rs
index d79c8b8..907a26f 100644
--- a/radius/src/core/rfc2865.rs
+++ b/radius/src/core/rfc2865.rs
@@ -150,6 +150,7 @@ use std::net::Ipv4Addr;
 
 use crate::core::avp::{AVPError, AVPType, AVP};
 use crate::core::packet::Packet;
+use crate::core::vsa::VSA;
 
 pub const USER_NAME_TYPE: AVPType = 1;
 /// Delete all of `user_name` values from a packet.
@@ -357,6 +358,12 @@ pub fn lookup_all_framed_ip_address(packet: &Packet) -> Result<Vec<Ipv4Addr>, AV
     Ok(vec)
 }
 
+/// Add `vsa_attribute` vsa value to a packet.
+pub fn add_vsa_attribute(packet: &mut Packet, value: &VSA) {
+    // packet.add(AVP::from_ipv4(FRAMED_IP_ADDRESS_TYPE, value));
+    packet.add(AVP::from_bytes(VENDOR_SPECIFIC_TYPE, &value.message()));
+}
+
 pub const FRAMED_IP_NETMASK_TYPE: AVPType = 9;
 /// Delete all of `framed_ip_netmask` values from a packet.
 pub fn delete_framed_ip_netmask(packet: &mut Packet) {
diff --git a/radius/src/core/vsa.rs b/radius/src/core/vsa.rs
new file mode 100644
index 0000000..62ed77b
--- /dev/null
+++ b/radius/src/core/vsa.rs
@@ -0,0 +1,35 @@
+const SINGLE_FIELDS_COUNT: usize = 3;
+
+/// This struct represents a attribute-value pair.
+#[derive(Debug, Clone, PartialEq)]
+pub struct VSA {
+    vendor_id: Vec<u8>,
+    type_id: u8,
+    length: u8,
+    tag: u8,
+    value: Vec<u8>,
+}
+
+impl VSA {
+    pub fn new(vendor_id: i32, type_id: u8, tag: u8, value: &str) -> VSA {
+        VSA {
+            vendor_id: vendor_id.to_be_bytes().to_vec(),
+            type_id,
+            length: (SINGLE_FIELDS_COUNT + value.len()) as u8,
+            tag: tag,
+            value: value.as_bytes().to_vec(),
+        }
+    }
+
+    pub fn len(&self) -> usize {
+        self.length as usize
+    }
+
+    pub fn message(&self) -> Vec<u8> {
+        let mut msg = vec![self.type_id, self.length, self.tag];
+        msg.splice(0..0, self.vendor_id.iter().cloned());
+        msg.append(&mut self.value.clone());
+
+        msg
+    }
+}